Pub Date : 2026-04-01Epub Date: 2026-01-28DOI: 10.1016/j.synthmet.2026.118100
Van Hau Vo Le, Corinne Binet, Valérie Gaucher, Jean-François Brun
In this study, the effect of the type of carbon nanotubes (CNTs) including multi-walled CNTs (MWCNTs), single-walled CNTs (SWCNTs), and carboxylic acid functionalized single-walled CNTs (SWCNTs-COOH) on the thermoelectric properties of poly(lactic acid)/CNT nanocomposite films has been investigated. The influence of the CNT weight fraction (from 2 to 40 wt%) and of temperature (from 300 to 400 K) was also discussed. The nanocomposites filled with SWCNTs exhibit the best thermoelectric performance with a maximum ZT value of 0.02 at 300 K for the sample containing 40 wt% CNTs. It is also shown that although SWCNTs-COOH significantly increase the Seebeck values, they also slightly decrease the electrical conductivity, resulting in no improvement regarding the ZT values. Finally, the ZT values almost doubled between 300 and 400 K, with maximum values of 0.02 at 300 K and of 0.04 at 400 K for 40 wt% SWCNTs. These values are the best ZT values that can be found in the literature for an insulating polymer filled with single-walled carbon nanotubes and thus may contribute to the development of flexible organic thermoelectric generators.
{"title":"Effect of carbon nanotube type on the thermoelectric performance of poly(lactic acid)/carbon nanotube composite thin films","authors":"Van Hau Vo Le, Corinne Binet, Valérie Gaucher, Jean-François Brun","doi":"10.1016/j.synthmet.2026.118100","DOIUrl":"10.1016/j.synthmet.2026.118100","url":null,"abstract":"<div><div>In this study, the effect of the type of carbon nanotubes (CNTs) including multi-walled CNTs (MWCNTs), single-walled CNTs (SWCNTs), and carboxylic acid functionalized single-walled CNTs (SWCNTs-COOH) on the thermoelectric properties of poly(lactic acid)/CNT nanocomposite films has been investigated. The influence of the CNT weight fraction (from 2 to 40 wt%) and of temperature (from 300 to 400 K) was also discussed. The nanocomposites filled with SWCNTs exhibit the best thermoelectric performance with a maximum ZT value of 0.02 at 300 K for the sample containing 40 wt% CNTs. It is also shown that although SWCNTs-COOH significantly increase the Seebeck values, they also slightly decrease the electrical conductivity, resulting in no improvement regarding the ZT values. Finally, the ZT values almost doubled between 300 and 400 K, with maximum values of 0.02 at 300 K and of 0.04 at 400 K for 40 wt% SWCNTs. These values are the best ZT values that can be found in the literature for an insulating polymer filled with single-walled carbon nanotubes and thus may contribute to the development of flexible organic thermoelectric generators.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118100"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-26DOI: 10.1016/j.synthmet.2026.118099
Israel da Luz Rodrigues , Achilley Nahid Barros Costa , Leonardo Tadeu Boaes Mendonça , Gricirene Sousa Correia
A chemiresistive gas sensor based on a polyaniline (PANI) and zinc ferrite (ZnFe₂O₄) composite photothermally activated by near-infrared (NIR) irradiation was developed and systematically investigated. ZnFe₂O₄ microspheres with a well-defined cubic spinel structure and an average diameter of 679 ± 47 nm were synthesized via a hydrothermal route and subsequently coated with PANI through in situ oxidative polymerization, resulting in a homogeneous hybrid composite with a reduced crystallite size of 36.6 nm, compared to 54.2 nm for pristine ZnFe₂O₄. Structural and spectroscopic analyses by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet–visible (UV–Vis) spectroscopy confirmed strong interfacial interactions between PANI and ZnFe₂O₄. FT-IR spectra showed characteristic ferrite bands at 441 and 594 cm⁻¹ and PANI bands at 1115, 1285, and 1620 cm⁻¹ , with noticeable band shifts in the composite, indicating interfacial coupling. UV–Vis analysis revealed absorption bands of PANI at 390 nm (π–π* transition) and 837 nm (polaronic excitation), while the composite exhibited a reduced optical bandgap from 2.44 eV (pure PANI) to 2.39 eV, evidencing enhanced electronic interaction between the organic and inorganic phases. Photothermal assays under NIR irradiation (850 nm, 660 mW) demonstrated that the composite exhibits high photothermal performance, achieving a maximum temperature increase (ΔT) of approximately 42 °C and a photothermal conversion efficiency of up to 90 % at a concentration of 1.0 mg mL⁻¹ , with excellent thermal stability over three heating–cooling cycles. Chemiresistive sensors fabricated by spin coating showed pronounced sensitivity toward reducing gases (4–25 ppm), with ammonia presenting the highest response and linearity (R² = 0.988). Under infrared irradiation provided by a light-emitting diode (LED), the sensor kinetics were significantly enhanced, with the response time for ammonia reduced by 73 % (from 20 s to 5.4 s) and the recovery time reduced by 66 %. In addition, photostimulation increased the sensitivity by approximately 48 % for ethanol and acetone, while selectively modulating the response toward larger molecules such as butanol. These results demonstrate that photothermal activation effectively replaces conventional thermal heating, positioning the PANI/ZnFe₂O₄ composite as a promising material for high-sensitivity, low-energy-consumption gas sensing applications.
{"title":"Photothermally stimulated gas sensing performance of PANI/ZnFe₂O₄ composite","authors":"Israel da Luz Rodrigues , Achilley Nahid Barros Costa , Leonardo Tadeu Boaes Mendonça , Gricirene Sousa Correia","doi":"10.1016/j.synthmet.2026.118099","DOIUrl":"10.1016/j.synthmet.2026.118099","url":null,"abstract":"<div><div>A chemiresistive gas sensor based on a polyaniline (PANI) and zinc ferrite (ZnFe₂O₄) composite photothermally activated by near-infrared (NIR) irradiation was developed and systematically investigated. ZnFe₂O₄ microspheres with a well-defined cubic spinel structure and an average diameter of 679 ± 47 nm were synthesized via a hydrothermal route and subsequently coated with PANI through <em>in situ</em> oxidative polymerization, resulting in a homogeneous hybrid composite with a reduced crystallite size of 36.6 nm, compared to 54.2 nm for pristine ZnFe₂O₄. Structural and spectroscopic analyses by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet–visible (UV–Vis) spectroscopy confirmed strong interfacial interactions between PANI and ZnFe₂O₄. FT-IR spectra showed characteristic ferrite bands at 441 and 594 cm⁻¹ and PANI bands at 1115, 1285, and 1620 cm⁻¹ , with noticeable band shifts in the composite, indicating interfacial coupling. UV–Vis analysis revealed absorption bands of PANI at 390 nm (π–π* transition) and 837 nm (polaronic excitation), while the composite exhibited a reduced optical bandgap from 2.44 eV (pure PANI) to 2.39 eV, evidencing enhanced electronic interaction between the organic and inorganic phases. Photothermal assays under NIR irradiation (850 nm, 660 mW) demonstrated that the composite exhibits high photothermal performance, achieving a maximum temperature increase (ΔT) of approximately 42 °C and a photothermal conversion efficiency of up to 90 % at a concentration of 1.0 mg mL⁻¹ , with excellent thermal stability over three heating–cooling cycles. Chemiresistive sensors fabricated by spin coating showed pronounced sensitivity toward reducing gases (4–25 ppm), with ammonia presenting the highest response and linearity (R² = 0.988). Under infrared irradiation provided by a light-emitting diode (LED), the sensor kinetics were significantly enhanced, with the response time for ammonia reduced by 73 % (from 20 s to 5.4 s) and the recovery time reduced by 66 %. In addition, photostimulation increased the sensitivity by approximately 48 % for ethanol and acetone, while selectively modulating the response toward larger molecules such as butanol. These results demonstrate that photothermal activation effectively replaces conventional thermal heating, positioning the PANI/ZnFe₂O₄ composite as a promising material for high-sensitivity, low-energy-consumption gas sensing applications.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118099"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metal-organic frameworks (MOFs) have emerged as promising candidates for electrode materials in energy storage applications. In this study, a nitrogen-doped graphene/cobalt-based metal-organic framework (N-G/Co-MOF) composite was synthesized via a solvothermal method and subsequently sulfurized to yield a cobalt sulfide hybrid (N-G/Co-S). The resulting material was comprehensively characterized using XRD, EDS, FT-IR, FE-SEM, TEM, BET, and TGA. FE-SEM images revealed a spherical morphology, while EDS elemental mapping confirmed a homogeneous distribution of constituent elements, with sulfur being the dominant species. The XRD pattern exhibited broad diffraction features indicative of partial amorphization, along with distinct crystalline peaks corresponding to cobalt sulfide phases. Electrochemical performance was evaluated in 3 M KOH electrolyte using cyclic voltammetry and galvanostatic charge–discharge measurements. The N-G/Co-S electrode delivered a specific capacitance of 518.3 F g⁻¹ at a current density of 1 A g⁻¹ , significantly outperforming the N-G/Co-MOF precursor, pristine Co-MOF, and N-G alone. Furthermore, the hybrid electrode achieved an energy density of 6.5 Wh kg⁻¹ at a power density of 150.5 W kg⁻¹ . Notably, after 5000 consecutive cycles at a scan rate of 50 mV s⁻¹ , the N-G/Co-S electrode retained 92.4 % of its initial capacitance, demonstrating good cycling stability and structural robustness.
金属有机框架（mof）已成为储能领域极具潜力的电极材料。在本研究中，通过溶剂热法合成了氮掺杂石墨烯/钴基金属有机骨架（N-G/Co-MOF）复合材料，随后进行硫化，得到硫化钴杂化物（N-G/Co-S）。采用XRD、EDS、FT-IR、FE-SEM、TEM、BET、TGA等手段对所得材料进行了全面表征。FE-SEM图像显示其呈球形形态，而EDS元素图证实其组成元素分布均匀，以硫为优势种。XRD谱图显示出部分非晶化的广泛衍射特征，以及与硫化钴相对应的明显的结晶峰。采用循环伏安法和恒流充放电法对3 M KOH电解质的电化学性能进行了评价。在电流密度为1 a g⁻¹ 时，N-G/Co-S电极的比电容为518.3 F g⁻¹ ，显著优于N-G/Co-MOF前体、原始Co-MOF和N-G。此外，混合电极的能量密度为6.5 Wh kg⁻¹ ，功率密度为150.5 W kg⁻¹ 。值得注意的是，在扫描速率为50 mV s⁻¹ 的连续5000次循环后，N-G/Co-S电极保留了其初始电容的92.4 %，表现出良好的循环稳定性和结构坚固性。
{"title":"Solvothermal synthesis of nitrogen-doped graphene/cobalt metal–organic framework derived cobalt sulfide nanohybrid for high-performance supercapacitor applications","authors":"Peyman Rezvani, Sayed Reza Hosseini, Shahram Ghasemi","doi":"10.1016/j.synthmet.2026.118118","DOIUrl":"10.1016/j.synthmet.2026.118118","url":null,"abstract":"<div><div>Metal-organic frameworks (MOFs) have emerged as promising candidates for electrode materials in energy storage applications. In this study, a nitrogen-doped graphene/cobalt-based metal-organic framework (N-G/Co-MOF) composite was synthesized via a solvothermal method and subsequently sulfurized to yield a cobalt sulfide hybrid (N-G/Co-S). The resulting material was comprehensively characterized using XRD, EDS, FT-IR, FE-SEM, TEM, BET, and TGA. FE-SEM images revealed a spherical morphology, while EDS elemental mapping confirmed a homogeneous distribution of constituent elements, with sulfur being the dominant species. The XRD pattern exhibited broad diffraction features indicative of partial amorphization, along with distinct crystalline peaks corresponding to cobalt sulfide phases. Electrochemical performance was evaluated in 3 M KOH electrolyte using cyclic voltammetry and galvanostatic charge–discharge measurements. The N-G/Co-S electrode delivered a specific capacitance of 518.3 F g⁻¹ at a current density of 1 A g⁻¹ , significantly outperforming the N-G/Co-MOF precursor, pristine Co-MOF, and N-G alone. Furthermore, the hybrid electrode achieved an energy density of 6.5 Wh kg⁻¹ at a power density of 150.5 W kg⁻¹ . Notably, after 5000 consecutive cycles at a scan rate of 50 mV s⁻¹ , the N-G/Co-S electrode retained 92.4 % of its initial capacitance, demonstrating good cycling stability and structural robustness.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118118"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-30DOI: 10.1016/j.synthmet.2026.118109
Shuang Luo , Feiyang Shen , Junyao Li , Wenrong Cai , Yong Kong
A molecularly imprinted electrochemical sensor is facilely designed for the detection of eugenol (EU). Copper nanoparticles (CuNPs) are first electrodeposited on the surface of a glassy carbon electrode (GCE) and act as the built-in probe. By using EU as the template molecules, o-phenylenediamine (o-PD) monomers are electropolymerized on the surface of the CuNPs/GCE. After the removal of the EU template molecules with the ethanol/water mixture, the molecularly imprinted electrochemical sensor is obtained. According to the cathodic peak currents (Ipc) of copper oxide generated from the oxidation of the CuNPs probe on the differential pulse voltammograms (DPVs), sensitive detection of EU can be achieved. The EU sensor shows a wide linear concentration range from 0.05 to 100 μM with a low limit of detection (LOD) of 0.022 μM under the optimized conditions. Additionally, the EU sensor exhibits excellent specificity, repeatability, reproducibility and stability. Finally, the developed EU sensor is used for the detection of EU in real samples, and reliable results are obtained.
{"title":"A molecularly imprinted electrochemical sensor using copper nanoparticles as built-in probe for eugenol detection","authors":"Shuang Luo , Feiyang Shen , Junyao Li , Wenrong Cai , Yong Kong","doi":"10.1016/j.synthmet.2026.118109","DOIUrl":"10.1016/j.synthmet.2026.118109","url":null,"abstract":"<div><div>A molecularly imprinted electrochemical sensor is facilely designed for the detection of eugenol (EU). Copper nanoparticles (CuNPs) are first electrodeposited on the surface of a glassy carbon electrode (GCE) and act as the built-in probe. By using EU as the template molecules, <em>o</em>-phenylenediamine (o-PD) monomers are electropolymerized on the surface of the CuNPs/GCE. After the removal of the EU template molecules with the ethanol/water mixture, the molecularly imprinted electrochemical sensor is obtained. According to the cathodic peak currents (<em>I</em><sub>pc</sub>) of copper oxide generated from the oxidation of the CuNPs probe on the differential pulse voltammograms (DPVs), sensitive detection of EU can be achieved. The EU sensor shows a wide linear concentration range from 0.05 to 100 μM with a low limit of detection (LOD) of 0.022 μM under the optimized conditions. Additionally, the EU sensor exhibits excellent specificity, repeatability, reproducibility and stability. Finally, the developed EU sensor is used for the detection of EU in real samples, and reliable results are obtained.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118109"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-26DOI: 10.1016/j.synthmet.2026.118098
Taeyong Shin , T.V.M. Sreekanth , B. Naresh , Yu-Rim Kim , Kisoo Yoo
The development of high-performance lithium-ion batteries (LIBs) necessitates advancements in separators and electrolytes to enhance safety, stability, and electrochemical efficiency. In this study, polyimide (PI) separators were fabricated via a controlled solution casting method, exhibiting a uniform porous structure for improved ion transport and thermal stability. The electrolyte system was optimized using ethylene carbonate (EC) and diethyl carbonate (DEC) with methyl propyl pyrrolidinium (MPPY), enhancing ionic conductivity and electrochemical stability. Electrochemical characterization using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) demonstrated superior performance with the EC-DEC electrolyte. Thermogravimetric analysis (TGA) confirmed the thermal robustness of the formulated electrolytes, while FTIR and XRD analyses validated the stability of the PI separator. Linear sweep voltammetry (LSV) further revealed an expanded electrochemical stability window with MPPY incorporation. These findings highlight the potential of PI separators and optimized electrolytes in advancing LIB technology for high-temperature and high-voltage applications.
{"title":"Polyimide separators and optimized EC-DEC:MPPY electrolytes for high-performance lithium-ion batteries","authors":"Taeyong Shin , T.V.M. Sreekanth , B. Naresh , Yu-Rim Kim , Kisoo Yoo","doi":"10.1016/j.synthmet.2026.118098","DOIUrl":"10.1016/j.synthmet.2026.118098","url":null,"abstract":"<div><div>The development of high-performance lithium-ion batteries (LIBs) necessitates advancements in separators and electrolytes to enhance safety, stability, and electrochemical efficiency. In this study, polyimide (PI) separators were fabricated via a controlled solution casting method, exhibiting a uniform porous structure for improved ion transport and thermal stability. The electrolyte system was optimized using ethylene carbonate (EC) and diethyl carbonate (DEC) with methyl propyl pyrrolidinium (MPPY), enhancing ionic conductivity and electrochemical stability. Electrochemical characterization using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) demonstrated superior performance with the EC-DEC electrolyte. Thermogravimetric analysis (TGA) confirmed the thermal robustness of the formulated electrolytes, while FTIR and XRD analyses validated the stability of the PI separator. Linear sweep voltammetry (LSV) further revealed an expanded electrochemical stability window with MPPY incorporation. These findings highlight the potential of PI separators and optimized electrolytes in advancing LIB technology for high-temperature and high-voltage applications.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118098"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-03DOI: 10.1016/j.synthmet.2026.118116
Po Chen , Huadeng Xie , Seonghun Jeong , Qinfang Zhang , Yuheng Li , Yingyao Zhang , Changduk Yang , Peng Gao
Organic conjugated polymers combine inherently low thermal conductivity, mechanical flexibility, and solution processability, making them promising candidates for flexible thermoelectric devices. However, their performance is often limited by a trade-off between electrical conductivity (σ) and the Seebeck coefficient (S), both of which depend strongly on charge-carrier transport efficiency and energy-level tunability. Here, we investigate a dithienopyran (DTP)–based conjugated polymer system in two variants: non-fluorinated P1 and fluorinated P2. Oxidative chemical doping with FeCl3 was employed to modulate carrier concentration and transport. Doping results show that P1 reaches a maximum σ of 104.11 S cm−1 and a peak thermoelectric power factor (PF) of 9.77 μW m−1 K−2, whereas fluorinated P2 is limited to 15.85 S cm−1 (≈15 % of P1) but achieves a significantly higher peak S of 161.56 μV K−1 and an optimal PF of 3.9 μW m−1 K−2. GIWAXS and density-of-states analyses reveal that fluorination disrupts π–π stacking and elevates energetic disorder, reducing mobility but allowing high-energy carriers to dominate transport, partially boosting S. It is confirmed that the FeCl3-induced Fermi-level shifts and electron extraction, with P1 showing stronger electronic reconstruction than P2 due to higher initial electron density. Temperature-dependent transport demonstrates continuous, thermally stable pathways in P1 and more thermally activated conduction in P2. These results provide mechanistic insight into how fluorine substitution modulates doping sensitivity, carrier localization, and the σ–S balance, offering a structure–doping co-optimization strategy for high-performance organic thermoelectrics.
有机共轭聚合物结合了固有的低导热性、机械灵活性和溶液可加工性，使其成为柔性热电器件的有希望的候选者。然而，它们的性能通常受到电导率（σ）和塞贝克系数(S)之间的权衡的限制，这两者都强烈依赖于载流子传输效率和能级可调性。在这里，我们研究了基于二噻吩吡喃（DTP）的共轭聚合物体系的两种变体：非氟化P1和氟化P2。采用氧化化学掺杂FeCl3来调节载流子浓度和输运。掺杂结果表明，P1的最大σ为104.11 S cm−1，峰值热电功率因数（PF）为9.77 μW m−1 K−2，而氟化P2的峰值为15.85 S cm−1(≈P1的15 %)，但峰值S为161.56 μV K−1，最佳PF为3.9 μW m−1 K−2。GIWAXS和态密度分析表明，氟化破坏π -π堆积，提高能量无序性，降低迁移率，但允许高能载流子主导传输，部分促进s。证实了fecl3诱导费米能级位移和电子提取，P1比P2由于更高的初始电子密度表现出更强的电子重建。温度依赖的转运在P1中表现出连续的、热稳定的途径，在P2中表现出更多的热激活传导。这些结果为氟取代如何调节掺杂灵敏度、载流子局部化和σ-S平衡提供了机制见解，为高性能有机热电材料提供了结构掺杂协同优化策略。
{"title":"Balancing conductivity and seebeck in D–A polymers: Fluorine modification and optimized FeCl3 chemical doping","authors":"Po Chen , Huadeng Xie , Seonghun Jeong , Qinfang Zhang , Yuheng Li , Yingyao Zhang , Changduk Yang , Peng Gao","doi":"10.1016/j.synthmet.2026.118116","DOIUrl":"10.1016/j.synthmet.2026.118116","url":null,"abstract":"<div><div>Organic conjugated polymers combine inherently low thermal conductivity, mechanical flexibility, and solution processability, making them promising candidates for flexible thermoelectric devices. However, their performance is often limited by a trade-off between electrical conductivity (σ) and the Seebeck coefficient (S), both of which depend strongly on charge-carrier transport efficiency and energy-level tunability. Here, we investigate a dithienopyran (DTP)–based conjugated polymer system in two variants: non-fluorinated P1 and fluorinated P2. Oxidative chemical doping with FeCl<sub>3</sub> was employed to modulate carrier concentration and transport. Doping results show that P1 reaches a maximum <em>σ</em> of 104.11 S cm<sup>−1</sup> and a peak thermoelectric power factor (PF) of 9.77 μW m<sup>−1</sup> K<sup>−2</sup>, whereas fluorinated P2 is limited to 15.85 S cm<sup>−1</sup> (≈15 % of P1) but achieves a significantly higher peak S of 161.56 μV K<sup>−1</sup> and an optimal PF of 3.9 μW m<sup>−1</sup> K<sup>−2</sup>. GIWAXS and density-of-states analyses reveal that fluorination disrupts π–π stacking and elevates energetic disorder, reducing mobility but allowing high-energy carriers to dominate transport, partially boosting <em>S</em>. It is confirmed that the FeCl<sub>3</sub>-induced Fermi-level shifts and electron extraction, with P1 showing stronger electronic reconstruction than P2 due to higher initial electron density. Temperature-dependent transport demonstrates continuous, thermally stable pathways in P1 and more thermally activated conduction in P2. These results provide mechanistic insight into how fluorine substitution modulates doping sensitivity, carrier localization, and the <em>σ</em>–<em>S</em> balance, offering a structure–doping co-optimization strategy for high-performance organic thermoelectrics.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118116"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Graphitic carbon nitride (g-C3N4) has emerged as a promising non-metal, metal-free semiconductor for solar energy conversion and environmental remediation. In this work, a scalable, template-free synthesis of halogen-doped g-C3N4 nanosheets (X = F, Br, I) was developed via urea–halogen complexes using a simple two-step thermal decomposition strategy. The obtained F-gCN, Br-gCN, and I-gCN photocatalysts exhibited narrowed band gaps, enhanced visible-light absorption, improved charge-carrier separation, higher surface areas, and nanosheet morphologies, which synergistically enhanced their photocatalytic performance. Photocatalytic degradation tests using methylene blue (MB) and rhodamine 6 G (R6G) showed degradation efficiencies of 98 % and 97 %, respectively, within short irradiation times. Degradation intermediates were identified by GC–MS analysis, and mung bean seed germination tests confirmed the reduced toxicity of the treated wastewater, demonstrating its potential agricultural applicability. Frontier molecular orbital (FMO) analysis provided insights into dye reactivity. For malachite green (MG), the HOMO and LUMO energies were −3.45 and −2.73 eV (ΔEgap = 0.72 eV), while for R6G they were −2.09 and −1.70 eV (ΔEgap = 0.39 eV). These narrow energy gaps indicated facile visible-light transitions and strong photoactivity. MG exhibited a higher ionization potential (3.45 eV) and electron affinity (2.73 eV), suggesting greater stability and stronger electron-accepting ability than R6G. In contrast, R6G showed lower hardness (0.20 eV) and higher softness (2.50 eV⁻¹), indicating enhanced chemical reactivity in accordance with the Parr–Pearson HSAB theory. The delocalization of HOMO and LUMO over π-conjugated frameworks accounted for strong light absorption and efficient dye–semiconductor interactions. Overall, this study presents a promising strategy for the rational design of metal-free photocatalysts for environmental remediation and sustainable agriculture.
石墨化氮化碳（g-C3N4）是一种很有前途的非金属、无金属半导体材料，可用于太阳能转换和环境修复。在这项工作中，利用简单的两步热分解策略，通过尿素-卤素配合物，开发了一种可扩展的，无模板的卤素掺杂g-C3N4纳米片（X = F, Br， I）的合成方法。所得的F-gCN、Br-gCN和I-gCN光催化剂具有窄带隙、增强可见光吸收、改善电荷载流子分离、更高的比表面积和纳米片形貌等特性，这些特性协同提高了它们的光催化性能。亚甲基蓝（MB）和罗丹明6 G （R6G）的光催化降解试验表明，在短照射时间内，降解效率分别为98 %和97 %。通过气相色谱-质谱分析鉴定了降解中间体，绿豆种子萌发试验证实了处理后废水的毒性降低，证明了其潜在的农业适用性。前沿分子轨道（FMO）分析提供了对染料反应性的深入了解。孔雀石绿（MG）的HOMO和LUMO能量分别为−3.45和−2.73 eV （ΔEgap = 0.72 eV）， R6G的HOMO和LUMO能量分别为−2.09和−1.70 eV （ΔEgap = 0.39 eV）。这些狭窄的能隙表明容易的可见光跃迁和强的光活性。MG具有更高的电离势（3.45 eV）和电子亲和力（2.73 eV），表明其稳定性和电子接受能力强于R6G。相反，R6G表现出较低的硬度（0.20 eV）和较高的柔软度（2.50 eV⁻¹），表明根据Parr-Pearson HSAB理论，R6G的化学反应性增强。HOMO和LUMO在π共轭框架上的离域导致了强光吸收和高效染料-半导体相互作用。总之，本研究为合理设计用于环境修复和可持续农业的无金属光催化剂提供了一个有希望的策略。
{"title":"Integrating DFT insights and photocatalytic performance of halogen-doped graphitic carbon nitride for sustainable wastewater remediation","authors":"Dhanapal Vasu , Moorthi Pichumani , Te-Wei Chiu , Shih-Hsien Chang","doi":"10.1016/j.synthmet.2026.118084","DOIUrl":"10.1016/j.synthmet.2026.118084","url":null,"abstract":"<div><div>Graphitic carbon nitride (g-C<sub>3</sub>N<sub>4</sub>) has emerged as a promising non-metal, metal-free semiconductor for solar energy conversion and environmental remediation. In this work, a scalable, template-free synthesis of halogen-doped g-C<sub>3</sub>N<sub>4</sub> nanosheets (X = F, Br, I) was developed via urea–halogen complexes using a simple two-step thermal decomposition strategy. The obtained F-gCN, Br-gCN, and I-gCN photocatalysts exhibited narrowed band gaps, enhanced visible-light absorption, improved charge-carrier separation, higher surface areas, and nanosheet morphologies, which synergistically enhanced their photocatalytic performance. Photocatalytic degradation tests using methylene blue (MB) and rhodamine 6 G (R6G) showed degradation efficiencies of 98 % and 97 %, respectively, within short irradiation times. Degradation intermediates were identified by GC–MS analysis, and mung bean seed germination tests confirmed the reduced toxicity of the treated wastewater, demonstrating its potential agricultural applicability. Frontier molecular orbital (FMO) analysis provided insights into dye reactivity. For malachite green (MG), the HOMO and LUMO energies were −3.45 and −2.73 eV (ΔEgap = 0.72 eV), while for R6G they were −2.09 and −1.70 eV (ΔEgap = 0.39 eV). These narrow energy gaps indicated facile visible-light transitions and strong photoactivity. MG exhibited a higher ionization potential (3.45 eV) and electron affinity (2.73 eV), suggesting greater stability and stronger electron-accepting ability than R6G. In contrast, R6G showed lower hardness (0.20 eV) and higher softness (2.50 eV⁻¹), indicating enhanced chemical reactivity in accordance with the Parr–Pearson HSAB theory. The delocalization of HOMO and LUMO over π-conjugated frameworks accounted for strong light absorption and efficient dye–semiconductor interactions. Overall, this study presents a promising strategy for the rational design of metal-free photocatalysts for environmental remediation and sustainable agriculture.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118084"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-30DOI: 10.1016/j.synthmet.2026.118111
Roberto Villarroel , Hilario Martines-Arano , Emigdio Chávez-Ángel , Samuel Hevia , José Antonio García-Merino
High-temperature thermionics cathodes require materials that combine structural robustness with efficient thermal and electrical transport. This work investigates the effects of laser annealing on the thermionic performance of vertically aligned carbon nanotube (CNT) arrays cathodes. Post-growth annealing at 1100 °C enhances crystallinity, as confirmed by reduced Raman ID/IG ratio from 1.02 to 0.49 and improved nanotube ordering with smaller diameters observed by scanning electron microscopy. Under near-infrared laser irradiances up to 11.0 MW/m², annealed CNTs exhibit higher photo-thermionic emission, improved responsivity, and increased resistance to laser-induced ablation compared to as-grown samples. To probe structural disorder beyond conventional metrics, we introduce a chaos-based electrical characterization using the Rössler chaotic attractor model. Electrical trajectories generated from CNT–CNT and CNT–Si configurations exhibit distinct chaotic signatures that correlate with defect density and crystallinity. This chaos-based electrical approach directly correlates nanoscale structure with emission performance, enabling the development of highly resilient CNT cathodes for extreme optoelectronic environments.
{"title":"Enhanced thermionic emission from annealed CNT cathodes assessed via chaos-based electrical diagnostics","authors":"Roberto Villarroel , Hilario Martines-Arano , Emigdio Chávez-Ángel , Samuel Hevia , José Antonio García-Merino","doi":"10.1016/j.synthmet.2026.118111","DOIUrl":"10.1016/j.synthmet.2026.118111","url":null,"abstract":"<div><div>High-temperature thermionics cathodes require materials that combine structural robustness with efficient thermal and electrical transport. This work investigates the effects of laser annealing on the thermionic performance of vertically aligned carbon nanotube (CNT) arrays cathodes. Post-growth annealing at 1100 °C enhances crystallinity, as confirmed by reduced Raman ID/IG ratio from 1.02 to 0.49 and improved nanotube ordering with smaller diameters observed by scanning electron microscopy. Under near-infrared laser irradiances up to 11.0 MW/m², annealed CNTs exhibit higher photo-thermionic emission, improved responsivity, and increased resistance to laser-induced ablation compared to as-grown samples. To probe structural disorder beyond conventional metrics, we introduce a chaos-based electrical characterization using the Rössler chaotic attractor model. Electrical trajectories generated from CNT–CNT and CNT–Si configurations exhibit distinct chaotic signatures that correlate with defect density and crystallinity. This chaos-based electrical approach directly correlates nanoscale structure with emission performance, enabling the development of highly resilient CNT cathodes for extreme optoelectronic environments.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118111"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-04DOI: 10.1016/j.synthmet.2026.118110
Kai Zhang , Yongyan Xu
Dimethyl methylphosphonate (DMMP), a simulant for organophosphate nerve agents, was investigated for its adsorption and detection on Al-doped graphene and Al-doped h-BN monolayers. Our workflow integrated machine learning interatomic potentials (MLIPs) for high-throughput configurational sampling and global minimum identification, followed by Density Functional Theory (DFT) for rigorous electronic characterization. The CHGNet-based MLIP was quantitatively validated against CASTEP/PBE-D3 results, showing structural deviations of less than 0.5 % for surface deformation angles.
Control calculations on pristine graphene and h-BN reveal weak physisorption (Eads≈−0.42/−0.20 eV) and negligible electronic exchange (0.0 to −0.04 e), highlighting a fundamental lack of sensitivity in non-functionalized substrates. In contrast, Al-doping introduces electrophilic active sites that facilitate a transition to strong chemisorption, resulting in substantial local lattice distortions and significant charge donation. DMMP interaction with Al-graphene is highly exothermic (Eads=−3.12 eV), characterized by a prominent Fermi level shift from −2.83 to −1.79 eV. While Al-h-BN supports comparatively weaker adsorption (Eads=−1.51 eV), it exhibits significant energy bandgap modulation, narrowing from 4.39 to 2.79 eV (ΔEg≈32 %).
PDOS and CDD analyses reveal that adsorption is stabilized by electrostatic polarization and substrate-mediated charge redistribution rather than direct Al–O covalent bonding. Recovery time analysis suggests that while Al-graphene is effectively irreversible under thermal conditions, Al-h-BN enables practical reversibility. Ultimately, these materials provide distinct but complementary sensing profiles: Al-graphene serves as an ideal platform for ultra-sensitive, single-use detection, whereas Al-h-BN offers a balanced solution for selective and recyclable gas sensing applications.
{"title":"Machine learning-accelerated DFT study of Al-doped graphene and h-BN: Contrasting sensing mechanisms for organophosphate (DMMP) detection","authors":"Kai Zhang , Yongyan Xu","doi":"10.1016/j.synthmet.2026.118110","DOIUrl":"10.1016/j.synthmet.2026.118110","url":null,"abstract":"<div><div>Dimethyl methylphosphonate (DMMP), a simulant for organophosphate nerve agents, was investigated for its adsorption and detection on Al-doped graphene and Al-doped <em>h</em>-BN monolayers. Our workflow integrated machine learning interatomic potentials (MLIPs) for high-throughput configurational sampling and global minimum identification, followed by Density Functional Theory (DFT) for rigorous electronic characterization. The CHGNet-based MLIP was quantitatively validated against CASTEP/PBE-D3 results, showing structural deviations of less than 0.5 % for surface deformation angles.</div><div>Control calculations on pristine graphene and <em>h</em>-BN reveal weak physisorption (<em>E</em><sub><em>ads</em></sub>≈−0.42/−0.20 eV) and negligible electronic exchange (0.0 to −0.04 <em>e</em>), highlighting a fundamental lack of sensitivity in non-functionalized substrates. In contrast, Al-doping introduces electrophilic active sites that facilitate a transition to strong chemisorption, resulting in substantial local lattice distortions and significant charge donation. DMMP interaction with Al-graphene is highly exothermic (<em>E</em><sub><em>ads</em></sub>=−3.12 eV), characterized by a prominent Fermi level shift from −2.83 to −1.79 eV. While Al-<em>h</em>-BN supports comparatively weaker adsorption (<em>E</em><sub><em>ads</em></sub>=−1.51 eV), it exhibits significant energy bandgap modulation, narrowing from 4.39 to 2.79 eV (Δ<em>E</em><sub><em>g</em></sub>≈32 %).</div><div>PDOS and CDD analyses reveal that adsorption is stabilized by electrostatic polarization and substrate-mediated charge redistribution rather than direct Al–O covalent bonding. Recovery time analysis suggests that while Al-graphene is effectively irreversible under thermal conditions, Al-<em>h</em>-BN enables practical reversibility. Ultimately, these materials provide distinct but complementary sensing profiles: Al-graphene serves as an ideal platform for ultra-sensitive, single-use detection, whereas Al-<em>h</em>-BN offers a balanced solution for selective and recyclable gas sensing applications.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118110"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-21DOI: 10.1016/j.synthmet.2026.118081
Jana Mišurović , Danica Bajuk-Bogdanović , Nemanja Gavrilov , Ana Popović-Bijelić , Gordana Ćirić-Marjanović
To improve the synthesis of polyaniline (PANI) by the oxidative polymerization, there is a great interest in replacing common oxidants (such as peroxydisulfate), which give undesirable/harmful products, with environmentally-friendly ones. Also, from an industrial perspective, it is highly desirable to accelerate the polymerization reaction, which can be achieved simply by adding small amount of aniline dimer to the reaction mixture. In this study, we combined these two approaches and examined the influence of para-aminodiphenylamine (p-ADPA) addition on the oxidative polymerization of aniline using H2O2 as the main, eco-friendly oxidant, whose reduction yields only water, and magnetite (Fe3O4) nanoparticles (NPs) as a low-cost, easily prepared, reusable, and environmentally safe catalyst. The results showed that p-ADPA accelerates the polymerization reaction, even enabling its initiation before the oxidant is added to the monomer (aniline/p-ADPA) and catalyst mixture. The influence of polymerization time and the amount of p-ADPA and Fe3O4 NPs on the yield, molecular structure, electrical conductivity, crystallinity, paramagnetic properties and morphology of polymerization products was investigated. FTIR, UV-Vis-NIR, and Raman spectra, along with electrical conductivity measurements, showed that prolonging the reaction time from 1 to 7 days promotes the formation of linear PANI-type polymer chains and leads to higher electrical conductivity, with a maximum value of 9.7 ∙ 10−3 S cm−1. While increasing the amount of p-ADPA positively affected both the rate of polymer formation and the final product conductivity, increasing the amount of Fe3O4 NPs catalyst increased the reaction rate and the final product yield, but did not improve its conductivity.
为了改进聚苯胺（PANI）的氧化聚合合成，人们对用环境友好的氧化剂取代常见的氧化剂（如过硫酸氢盐）有很大的兴趣，这些氧化剂会产生不良/有害的产物。此外，从工业角度来看，加速聚合反应是非常可取的，这可以通过在反应混合物中加入少量苯胺二聚体来实现。在这项研究中，我们将这两种方法结合起来，研究了对氨基二苯胺（p-ADPA）的添加对苯胺氧化聚合的影响，以H2O2为主要的环保氧化剂，其还原只产生水，而磁铁矿（Fe3O4）纳米颗粒（NPs）作为一种低成本、易于制备、可重复使用且环保的催化剂。结果表明，对adpa加速了聚合反应，甚至在氧化剂加入到单体（苯胺/对adpa）和催化剂混合物中之前就可以引发聚合反应。考察了聚合时间、p-ADPA和Fe3O4 NPs用量对聚合产物产率、分子结构、电导率、结晶度、顺磁性和形貌的影响。FTIR、UV-Vis-NIR和拉曼光谱以及电导率测量表明，将反应时间从1天延长到7天，促进了线性聚苯胺型聚合物链的形成，并导致更高的电导率，最大值为9.7∙10−3 S cm−1。增加p-ADPA的用量对聚合物的形成速率和最终产物的电导率都有积极影响，而增加Fe3O4 NPs催化剂的用量可以提高反应速率和最终产物的产率，但不能提高其电导率。
{"title":"Influence of para-aminodiphenylamine addition on the polymerization of aniline with H2O2/Fe3O4 nanoparticles as an eco-friendly oxidant/catalyst system","authors":"Jana Mišurović , Danica Bajuk-Bogdanović , Nemanja Gavrilov , Ana Popović-Bijelić , Gordana Ćirić-Marjanović","doi":"10.1016/j.synthmet.2026.118081","DOIUrl":"10.1016/j.synthmet.2026.118081","url":null,"abstract":"<div><div>To improve the synthesis of polyaniline (PANI) by the oxidative polymerization, there is a great interest in replacing common oxidants (such as peroxydisulfate), which give undesirable/harmful products, with environmentally-friendly ones. Also, from an industrial perspective, it is highly desirable to accelerate the polymerization reaction, which can be achieved simply by adding small amount of aniline dimer to the reaction mixture. In this study, we combined these two approaches and examined the influence of <em>para</em>-aminodiphenylamine (p-ADPA) addition on the oxidative polymerization of aniline using H<sub>2</sub>O<sub>2</sub> as the main, eco-friendly oxidant, whose reduction yields only water, and magnetite (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles (NPs) as a low-cost, easily prepared, reusable, and environmentally safe catalyst. The results showed that p-ADPA accelerates the polymerization reaction, even enabling its initiation before the oxidant is added to the monomer (aniline/p-ADPA) and catalyst mixture. The influence of polymerization time and the amount of p-ADPA and Fe<sub>3</sub>O<sub>4</sub> NPs on the yield, molecular structure, electrical conductivity, crystallinity, paramagnetic properties and morphology of polymerization products was investigated. FTIR, UV-Vis-NIR, and Raman spectra, along with electrical conductivity measurements, showed that prolonging the reaction time from 1 to 7 days promotes the formation of linear PANI-type polymer chains and leads to higher electrical conductivity, with a maximum value of 9.7 ∙ 10<sup>−3</sup> S cm<sup>−1</sup>. While increasing the amount of p-ADPA positively affected both the rate of polymer formation and the final product conductivity, increasing the amount of Fe<sub>3</sub>O<sub>4</sub> NPs catalyst increased the reaction rate and the final product yield, but did not improve its conductivity.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"318 ","pages":"Article 118081"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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