Microbiologically influenced corrosion (MIC) of metals is a serious challenge where Manganese oxidizing bacteria (MOB) can play a relevant role. However, there is no consensus on how MOB influences corrosion mechanisms. This arises from the complexity of the corrosion process and the challenge of distinguishing the effects of chemicals from the biological contributions. In this work, the electrochemical characteristics of St37 carbon steel in a bacteria-free Mn broth medium were monitored for 5 h using the new technique of Dynamic Electrochemical Impedance Spectroscopy (DEIS). The results were compared with those from the classical electrochemical techniques to validate the new technique. DEIS accurately tracked corrosion processes in the media and analysis of the variation of parameters such as the polarization resistance (Rp), corrosion potential (E), and constant phase elements (n, and Y0) proved valuable insight in understanding the corrosion processes. The study reveals that, in a sterile Mn broth medium, the corrosion resistance of St37 steel improved over time due to the adsorption of yeast and (NH4)2Fe(SO4)2 on the surface. SEM and EDX results confirm the adsorption of protective deposits on the steel surface. The polarization resistance of St37 steel increased up to 12000 Ω cm2 at 5 h of measurement. The results from the DEIS technique conform with those from the classical techniques. The work therefore established the DEIS technique as reliable for corrosion measurements in a dynamic system. The results achieved can serve as a suitable baseline for future MIC studies induced by MOB.
{"title":"Dynamic Impedance-Based Monitoring of St37 Carbon Steel Corrosion in Sterilized Manganese Broth Medium","authors":"Husnu Gerengi, Pierangela Cristiani, Moses M. Solomon, Esra Ilhan-Sungur, Mesut Yıldız, Pawel Slepski","doi":"10.1016/j.electacta.2025.146011","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146011","url":null,"abstract":"Microbiologically influenced corrosion (MIC) of metals is a serious challenge where Manganese oxidizing bacteria (MOB) can play a relevant role. However, there is no consensus on how MOB influences corrosion mechanisms. This arises from the complexity of the corrosion process and the challenge of distinguishing the effects of chemicals from the biological contributions. In this work, the electrochemical characteristics of St37 carbon steel in a bacteria-free Mn broth medium were monitored for 5 h using the new technique of Dynamic Electrochemical Impedance Spectroscopy (DEIS). The results were compared with those from the classical electrochemical techniques to validate the new technique. DEIS accurately tracked corrosion processes in the media and analysis of the variation of parameters such as the polarization resistance (<em>R</em><sub>p</sub>), corrosion potential (<em>E</em>), and constant phase elements (<em>n</em>, and <em>Y</em><sub>0</sub>) proved valuable insight in understanding the corrosion processes. The study reveals that, in a sterile Mn broth medium, the corrosion resistance of St37 steel improved over time due to the adsorption of yeast and (NH<sub>4</sub>)<sub>2</sub>Fe(SO<sub>4</sub>)<sub>2</sub> on the surface. SEM and EDX results confirm the adsorption of protective deposits on the steel surface. The polarization resistance of St37 steel increased up to 12000 Ω cm<sup>2</sup> at 5 h of measurement. The results from the DEIS technique conform with those from the classical techniques. The work therefore established the DEIS technique as reliable for corrosion measurements in a dynamic system. The results achieved can serve as a suitable baseline for future MIC studies induced by MOB.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"16 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143672769","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}
The development of cost-effective and environmentally sustainable electrocatalysts is crucial for advancing the commercialization of proton exchange membrane fuel cells (PEMFCs). In this work, we investigate the effect of different silica leaching strategies on the synthesis of iron-nitrogen-carbon (FeNC) electrocatalysts for the oxygen reduction reaction (ORR). Three FeNC samples were prepared using SBA-15 mesoporous silica as the template and subjected to varying removal techniques: hydrofluoric acid (HF), sodium hydroxide followed by hydrochloric acid (NaOH+HCl), and an acid-free Teflon-assisted process. Physical-chemical characterization reveals significant differences in the surface area and porosity of the three catalysts. The specific surface areas of FeNC treated with NaOH+HCl and HF are 1352 m²/g and 1403 m²/g, respectively, while the Teflon-treated sample exhibits a much lower value of 732 m²/g. Electrochemical tests using a rotating ring disk electrode (RRDE) apparatus demonstrate superior ORR activity of the FeNC treated with NaOH+HCl, achieving onset potentials of 0.93 VRHE and 0.81 VRHE in alkaline and acidic media, respectively, outperforming the HF- and Teflon-treated counterparts . The HF treatment, while effective in removing silica and metallic impurities, poses environmental and safety challenges. The Teflon-assisted approach, despite its promise as a greener alternative, results in a lower surface area and diminished ORR activity, with onset potentials of 0.89 VRHE and 0.76 VRHE in alkaline and acidic media, respectively. This study highlights the importance of optimizing silica removal methods to balance the catalyst performance, safety and sustainability, with the NaOH+HCl method emerging as the most effective approach for producing high-performance FeNC ORR catalysts for fuel cell applications.
{"title":"Effect of silica leaching treatment during template-assisted synthesis on the performance of FeNC catalysts for oxygen reduction reaction","authors":"Giulia Gianola, Alessio Cosenza, Camille Roiron, Candido F. Pirri, Stefania Specchia, Plamen Atanassov, Juqin Zeng","doi":"10.1016/j.electacta.2025.146085","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146085","url":null,"abstract":"The development of cost-effective and environmentally sustainable electrocatalysts is crucial for advancing the commercialization of proton exchange membrane fuel cells (PEMFCs). In this work, we investigate the effect of different silica leaching strategies on the synthesis of iron-nitrogen-carbon (FeNC) electrocatalysts for the oxygen reduction reaction (ORR). Three FeNC samples were prepared using SBA-15 mesoporous silica as the template and subjected to varying removal techniques: hydrofluoric acid (HF), sodium hydroxide followed by hydrochloric acid (NaOH+HCl), and an acid-free Teflon-assisted process. Physical-chemical characterization reveals significant differences in the surface area and porosity of the three catalysts. The specific surface areas of FeNC treated with NaOH+HCl and HF are 1352 m²/g and 1403 m²/g, respectively, while the Teflon-treated sample exhibits a much lower value of 732 m²/g. Electrochemical tests using a rotating ring disk electrode (RRDE) apparatus demonstrate superior ORR activity of the FeNC treated with NaOH+HCl, achieving onset potentials of 0.93 V<sub>RHE</sub> and 0.81 V<sub>RHE</sub> in alkaline and acidic media, respectively, outperforming the HF- and Teflon-treated counterparts . The HF treatment, while effective in removing silica and metallic impurities, poses environmental and safety challenges. The Teflon-assisted approach, despite its promise as a greener alternative, results in a lower surface area and diminished ORR activity, with onset potentials of 0.89 V<sub>RHE</sub> and 0.76 V<sub>RHE</sub> in alkaline and acidic media, respectively. This study highlights the importance of optimizing silica removal methods to balance the catalyst performance, safety and sustainability, with the NaOH+HCl method emerging as the most effective approach for producing high-performance FeNC ORR catalysts for fuel cell applications.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"24 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143672781","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 : 2025-03-20DOI: 10.1016/j.electacta.2025.145919
JunHo Lee, Hyeonmuk Kang, JungHyeon Moon, Heechan Kang, GyuSeong Hwang, GeunHyeong Shin, GyungTae Kim, TaeHee Kim, EunAe Cho
Lithium-rich layered cathodes (LLCs) are considered to be promising next-generation materials for lithium-ion batteries (LIBs) due to their high specific capacity and energy density. However, their poor cyclability poses a significant challenge for commercial applications. In this study, we introduce a straightforward one-step electrode heat-treatment method involving a lithium fluoride (LiF) coating on conventional LLCs, without the need for additional coating precursors, to enhance the cyclability. During the heat-treatment, lithium residues (LiOH and Li2CO3) and the PVDF used as a binder react to form an amorphous LiF coating layer (LiF-LLC). Although LiF-LLC initially exhibited a lower capacity compared to pristine LLC (220.2 vs. 246.6 mAh g⁻¹) due to its higher overpotential, it demonstrated superior performance after 100 cycles at 0.2 C. LiF-LLC maintained a discharge capacity of 219.4 mAh g⁻¹ with 95.1 % retention, while pristine LLC showed an outcome of only 164.8 mAh g⁻¹ with 83.4 % retention. A comprehensive analysis revealed that the LiF coating layer effectively passivated the cathode interface, preventing transition metal dissolution and a phase transformation caused by a HF attack. Additionally, LiF-LLC exhibited higher lithium-ion diffusivity, lower interfacial impedance, and enhanced Mn- and O-ion redox activities. These findings demonstrate that the simple electrode heat-treatment significantly improves the cyclic stability of LLCs.
{"title":"Enhancement of the cyclic stability of a Li-excess layered oxide through a simple electrode treatment for LiF-coating","authors":"JunHo Lee, Hyeonmuk Kang, JungHyeon Moon, Heechan Kang, GyuSeong Hwang, GeunHyeong Shin, GyungTae Kim, TaeHee Kim, EunAe Cho","doi":"10.1016/j.electacta.2025.145919","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.145919","url":null,"abstract":"Lithium-rich layered cathodes (LLCs) are considered to be promising next-generation materials for lithium-ion batteries (LIBs) due to their high specific capacity and energy density. However, their poor cyclability poses a significant challenge for commercial applications. In this study, we introduce a straightforward one-step electrode heat-treatment method involving a lithium fluoride (LiF) coating on conventional LLCs, without the need for additional coating precursors, to enhance the cyclability. During the heat-treatment, lithium residues (LiOH and Li<sub>2</sub>CO<sub>3</sub>) and the PVDF used as a binder react to form an amorphous LiF coating layer (LiF-LLC). Although LiF-LLC initially exhibited a lower capacity compared to pristine LLC (220.2 vs. 246.6 mAh g⁻¹) due to its higher overpotential, it demonstrated superior performance after 100 cycles at 0.2 C. LiF-LLC maintained a discharge capacity of 219.4 mAh g⁻¹ with 95.1 % retention, while pristine LLC showed an outcome of only 164.8 mAh g⁻¹ with 83.4 % retention. A comprehensive analysis revealed that the LiF coating layer effectively passivated the cathode interface, preventing transition metal dissolution and a phase transformation caused by a HF attack. Additionally, LiF-LLC exhibited higher lithium-ion diffusivity, lower interfacial impedance, and enhanced Mn- and O-ion redox activities. These findings demonstrate that the simple electrode heat-treatment significantly improves the cyclic stability of LLCs.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"70 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660874","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 : 2025-03-20DOI: 10.1016/j.electacta.2025.146088
Leonardo Balducci, Mohsin Muhyuddin, Hamideh Darjazi, Giuseppina Meligrana, Carlo Santoro, Francesco Nobili
The exploitation of graphene oxide (GO)-based composites for fuel cell electrocatalysts has gained significant interest, yet the integration of iron oxide nanoparticles grafted on GO, doped with different metals, remains relatively unexplored. This study aims to fill this gap by synthesizing and characterizing Fe2O3 nanoparticles grafted on GO doped with two different metals, specifically magnesium and nickel, each at three different concentrations (6%, 12%, and 18% by weight). The successful doping and incorporation of Fe2O3 on the GO matrix is confirmed using X-ray diffraction (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) provides insights into the morphology and dispersion of Fe2O3 nanoparticles on the GO surface. Rotating Ring Disk Electrode (RRDE) is used to analyze the electrochemical activities towards oxygen reduction reaction (ORR). The results demonstrated improved electrocatalytic activity and selectivity with increasing metal concentration. Notably, the electrocatalysts with 6% Mg and 6% Ni doping exhibit superior peroxide scavenging properties. When 6% Ni is mixed with FePc600, it provides additional active sites devoted for the peroxide scavenging increasing the limiting current from 4.69 to 5.62 mA cm-2, halving the peroxide production, passing from 5.1% to 2.9%. Overall, this study provides insights into the tunable properties of Fe2O3@GO composites through metal doping, offering a versatile approach to enhance the performance of composite materials in various technological applications, and specifically suggests that Fe2O3 grafted on GO, modified with Mg and Ni, holds significant potential as a cocatalyst for ORR in energy devices such as alkaline fuel cells.
{"title":"Mg- and Ni-modified Fe2O3@rGO as enhanced peroxide scavenger cocatalysts in oxygen reduction reaction","authors":"Leonardo Balducci, Mohsin Muhyuddin, Hamideh Darjazi, Giuseppina Meligrana, Carlo Santoro, Francesco Nobili","doi":"10.1016/j.electacta.2025.146088","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146088","url":null,"abstract":"The exploitation of graphene oxide (GO)-based composites for fuel cell electrocatalysts has gained significant interest, yet the integration of iron oxide nanoparticles grafted on GO, doped with different metals, remains relatively unexplored. This study aims to fill this gap by synthesizing and characterizing Fe<sub>2</sub>O<sub>3</sub> nanoparticles grafted on GO doped with two different metals, specifically magnesium and nickel, each at three different concentrations (6%, 12%, and 18% by weight). The successful doping and incorporation of Fe<sub>2</sub>O<sub>3</sub> on the GO matrix is confirmed using X-ray diffraction (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) provides insights into the morphology and dispersion of Fe<sub>2</sub>O<sub>3</sub> nanoparticles on the GO surface. Rotating Ring Disk Electrode (RRDE) is used to analyze the electrochemical activities towards oxygen reduction reaction (ORR). The results demonstrated improved electrocatalytic activity and selectivity with increasing metal concentration. Notably, the electrocatalysts with 6% Mg and 6% Ni doping exhibit superior peroxide scavenging properties. When 6% Ni is mixed with FePc600, it provides additional active sites devoted for the peroxide scavenging increasing the limiting current from 4.69 to 5.62 mA cm<sup>-2</sup>, halving the peroxide production, passing from 5.1% to 2.9%. Overall, this study provides insights into the tunable properties of Fe<sub>2</sub>O<sub>3</sub>@GO composites through metal doping, offering a versatile approach to enhance the performance of composite materials in various technological applications, and specifically suggests that Fe<sub>2</sub>O<sub>3</sub> grafted on GO, modified with Mg and Ni, holds significant potential as a cocatalyst for ORR in energy devices such as alkaline fuel cells.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"32 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666480","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 : 2025-03-20DOI: 10.1016/j.electacta.2025.146061
Matteo Palluzzi, Marita Afiandika, Shizhao Xiong, Akiko Tsurumaki, Paola D'Angelo, Aleksandar Matic, Maria Assunta Navarra
Zinc-ion batteries (ZIBs) offer promising energy storage solutions due to their high capacity, abundance and low cost of raw materials, and stability in air of zinc. Despite these advantages, ZIBs with aqueous electrolytes struggle with issues like dendrite formation, hydrogen evolution, and zinc corrosion. This study explores the use of low-transition-temperature (LTT) mixtures as electrolytes to address these critical issues of ZIBs. Novel LTT electrolytes at different molar ratios of Zn(TFSI)₂ and ethylene glycol (EG), chosen for their cost-effectiveness, were prepared. The LTT electrolytes were characterized, through spectroscopic and electrochemical methods, and the most promising one (Zn:EG 1:7) was further evaluated in a full cell by coupling Zn metal with a K⁺-doped vanadium oxide (K₀.₅V₂O₅, KVO) cathode. The full cell shows an excellent stability upon cycling and notable suppression of the dendritic growth, but limited capacities. Our electrolyte system holds significant potential for advancing ZIB technology if further developed.
{"title":"A low-transition-temperature electrolyte based on ethylene glycol for rechargeable zinc-ion batteries","authors":"Matteo Palluzzi, Marita Afiandika, Shizhao Xiong, Akiko Tsurumaki, Paola D'Angelo, Aleksandar Matic, Maria Assunta Navarra","doi":"10.1016/j.electacta.2025.146061","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146061","url":null,"abstract":"Zinc-ion batteries (ZIBs) offer promising energy storage solutions due to their high capacity, abundance and low cost of raw materials, and stability in air of zinc. Despite these advantages, ZIBs with aqueous electrolytes struggle with issues like dendrite formation, hydrogen evolution, and zinc corrosion. This study explores the use of low-transition-temperature (LTT) mixtures as electrolytes to address these critical issues of ZIBs. Novel LTT electrolytes at different molar ratios of Zn(TFSI)₂ and ethylene glycol (EG), chosen for their cost-effectiveness, were prepared. The LTT electrolytes were characterized, through spectroscopic and electrochemical methods, and the most promising one (Zn:EG 1:7) was further evaluated in a full cell by coupling Zn metal with a K⁺-doped vanadium oxide (K₀.₅V₂O₅, KVO) cathode. The full cell shows an excellent stability upon cycling and notable suppression of the dendritic growth, but limited capacities. Our electrolyte system holds significant potential for advancing ZIB technology if further developed.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"91 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660872","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 : 2025-03-20DOI: 10.1016/j.electacta.2025.146086
B. Díaz, A. Diéguez, C. Gil, M. González, X.R. Nóvoa, C. Paz, C. Pérez
Conducting fibre-reinforced cement-based materials is of great technological interest for their mechanical performance and multifunctional character, from structural to self-sensing applications. The composite's properties depend mainly on the fibre's concentration. However, for a given nominal concentration, the critical practical aspect is the degree of dispersibility achieved during the mixing process. This unsolved problem that greatly conditions the reproducibility of mixes. The present research addresses this problem using the electrochemical impedance spectroscopy technique.Different cement paste model samples were loaded with stainless steel wires acting as reinforcing fibres. The system's impedance was recorded mainly from 50 MHz to 20 Hz, but lower frequencies were also explored. The results show that the presence of fibres modifies the impedance spectra, decreasing the apparent resistivity measured. This result was already reported in the literature. What is new in this research is the fact that the orientation of the fibres with respect to the electric field used for testing significantly affects the impedance spectra. The numerical simulations show that the presence of fibres modifies the current lines in a manner largely dependent on the ratio of the interfacial impedance to the cementitious impedance, which defines the minimal size for resolving orientation effects.
{"title":"High-frequency impedance measurements on cement paste loaded with steel fibres","authors":"B. Díaz, A. Diéguez, C. Gil, M. González, X.R. Nóvoa, C. Paz, C. Pérez","doi":"10.1016/j.electacta.2025.146086","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146086","url":null,"abstract":"Conducting fibre-reinforced cement-based materials is of great technological interest for their mechanical performance and multifunctional character, from structural to self-sensing applications. The composite's properties depend mainly on the fibre's concentration. However, for a given nominal concentration, the critical practical aspect is the degree of dispersibility achieved during the mixing process. This unsolved problem that greatly conditions the reproducibility of mixes. The present research addresses this problem using the electrochemical impedance spectroscopy technique.Different cement paste model samples were loaded with stainless steel wires acting as reinforcing fibres. The system's impedance was recorded mainly from 50 MHz to 20 Hz, but lower frequencies were also explored. The results show that the presence of fibres modifies the impedance spectra, decreasing the apparent resistivity measured. This result was already reported in the literature. What is new in this research is the fact that the orientation of the fibres with respect to the electric field used for testing significantly affects the impedance spectra. The numerical simulations show that the presence of fibres modifies the current lines in a manner largely dependent on the ratio of the interfacial impedance to the cementitious impedance, which defines the minimal size for resolving orientation effects.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"49 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660873","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 : 2025-03-19DOI: 10.1016/j.electacta.2025.146079
Mpho S. Ratsoma, Hlengiwe Mathebula, Kearabetswe T. Boikanyo, Mesfin A. Kebede, Kwena D. Modibane, Gugu Kubheka, Mpho D.S. Lekgoathi, Katlego Makgopa
Heteroatom-rich materials have emerged as promising electrode materials for the development of high-performance electrochemical energy storage devices. This study investigated the electrochemical synergy of the N- and P-rich ammonium manganese phosphate hydrate (NH4MnPO4·H2O, Mn-AMP) decorated on N-doped reduced graphene oxide (N-rGO) as a potential hybrid battery-type electrode material for high energy and power supercapatteries. The half-cell analysis of the N-rGO/Mn-AMP nanohybrid demonstrated a high areal capacity of 147.4 µAh cm−2 (1061.6 mF cm−2) compared to 110.3 µAh cm−2 (794. mF cm−2) of Mn-AMP and 100.1 µAh cm−2 (720.4 mF cm−2) obtained from the N-rGO. A hybrid supercapacitor (HSC) was constructed using the N-rGO/Mn-AMP nanohybrid and activated carbon as the positive and negative electrodes, respectively. The AC//N-rGO/Mn-AMP nanohybrid HSC demonstrated a high specific capacity of 85.4 µAh cm−2 (205 mF cm−2)*, high areal energy of 50.6 µWh cm-2 with a corresponding areal power of 0.36 mW cm-2 at an areal current of 0.6 mA cm−2, as well as a maximum areal power of 5.15 mW cm-2 with areal energy of 19.1 µWh cm-2 at 10.0 mA cm−2. The HSC was able to demonstrate excellent electrochemical stability with ∼92% retention of the initial capacity, as well as 98.8% Coulombic efficiency after 10 000 GCD cycles at 3.0 mA cm−2. Computational studies of the N-rGO/Mn-AMP nanohybrid showed capacitance in the nanohybrid that could be attributed to the increase in conductivity due to the charge transfer between the Mn-AMP and N-rGO as a result of the strong hybridisation between the C 2p and O 2p states of N-rGO with O 2p and Mn 3d orbitals of Mn-AMP at both valance and conduction band. The experimental and molecular modelling studies have shown the synergy achieved by integrating Mn-AMP nanoplatelets with N-rGO nanosheets. This combination highlights the potential of the N-rGO/Mn-AMP nanohybrid as an electrode material for high-performance supercapacitors.
{"title":"Investigation of N-rGO/NH4MnPO4·H2O as battery-type electrode material for high-performance supercapatteries","authors":"Mpho S. Ratsoma, Hlengiwe Mathebula, Kearabetswe T. Boikanyo, Mesfin A. Kebede, Kwena D. Modibane, Gugu Kubheka, Mpho D.S. Lekgoathi, Katlego Makgopa","doi":"10.1016/j.electacta.2025.146079","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146079","url":null,"abstract":"Heteroatom-rich materials have emerged as promising electrode materials for the development of high-performance electrochemical energy storage devices. This study investigated the electrochemical synergy of the N- and P-rich ammonium manganese phosphate hydrate (NH<sub>4</sub>MnPO<sub>4</sub>·H<sub>2</sub>O, <em>Mn-AMP</em>) decorated on N-doped reduced graphene oxide (N-rGO) as a potential hybrid battery-type electrode material for high energy and power supercapatteries. The half-cell analysis of the N-rGO/Mn-AMP nanohybrid demonstrated a high areal capacity of 147.4 µAh cm<sup>−2</sup> (1061.6 mF cm<sup>−2</sup>) compared to 110.3 µAh cm<sup>−2</sup> (794. mF cm<sup>−2</sup>) of Mn-AMP and 100.1 µAh cm<sup>−2</sup> (720.4 mF cm<sup>−2</sup>) obtained from the N-rGO. A hybrid supercapacitor (HSC) was constructed using the N-rGO/Mn-AMP nanohybrid and activated carbon as the positive and negative electrodes, respectively. The AC//N-rGO/Mn-AMP nanohybrid HSC demonstrated a high specific capacity of 85.4 µAh cm<sup>−2</sup> (205 mF cm<sup>−2</sup>)*, high areal energy of 50.6 µWh cm<sup>-2</sup> with a corresponding areal power of 0.36 mW cm<sup>-2</sup> at an areal current of 0.6 mA cm<sup>−2</sup>, as well as a maximum areal power of 5.15 mW cm<sup>-2</sup> with areal energy of 19.1 µWh cm<sup>-2</sup> at 10.0 mA cm<sup>−2</sup>. The HSC was able to demonstrate excellent electrochemical stability with ∼92% retention of the initial capacity, as well as 98.8% Coulombic efficiency after 10 000 GCD cycles at 3.0 mA cm<sup>−2</sup>. Computational studies of the N-rGO/Mn-AMP nanohybrid showed capacitance in the nanohybrid that could be attributed to the increase in conductivity due to the charge transfer between the Mn-AMP and N-rGO as a result of the strong hybridisation between the C 2p and O 2p states of N-rGO with O 2p and Mn 3d orbitals of Mn-AMP at both valance and conduction band. The experimental and molecular modelling studies have shown the synergy achieved by integrating Mn-AMP nanoplatelets with N-rGO nanosheets. This combination highlights the potential of the N-rGO/Mn-AMP nanohybrid as an electrode material for high-performance supercapacitors.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"34 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653872","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 : 2025-03-19DOI: 10.1016/j.electacta.2025.146082
Isabell Wachta, Wei Nie, Gloria Alexander, Christopher S. Kley, Kannan Balasubramanian
Microsensors for resolving local pH are versatile analytical tools for studying reactions at solid-liquid interfaces in applications such as electrocatalysis and corrosion. However, the achievable temporal resolution is limited, hindering the operando investigation of local pH at surfaces in electrochemical reactions. Here, we present a methodology to achieve a high time resolution by deploying AC voltammetry with a pH microsensor. The sensor is composed of a gold ultramicroelectrode functionalized with electropolymerized methylene blue at its tip, allowing for continuous monitoring of pH in aqueous solutions in the neutral and acidic regime at a subsecond time resolution. As a proof-of-principle, we show that our sensors can be used for detecting interfacial pH at an electrified platinum nanoparticle-modified carbon electrode during the hydrogen and oxygen evolution reactions. The fast pH sensing capability is expected to open an avenue for routine operando studies of local pH at electrified interfaces.
{"title":"A fast voltammetric pH microsensor based on electropolymerization of methylene blue","authors":"Isabell Wachta, Wei Nie, Gloria Alexander, Christopher S. Kley, Kannan Balasubramanian","doi":"10.1016/j.electacta.2025.146082","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146082","url":null,"abstract":"Microsensors for resolving local pH are versatile analytical tools for studying reactions at solid-liquid interfaces in applications such as electrocatalysis and corrosion. However, the achievable temporal resolution is limited, hindering the operando investigation of local pH at surfaces in electrochemical reactions. Here, we present a methodology to achieve a high time resolution by deploying AC voltammetry with a pH microsensor. The sensor is composed of a gold ultramicroelectrode functionalized with electropolymerized methylene blue at its tip, allowing for continuous monitoring of pH in aqueous solutions in the neutral and acidic regime at a subsecond time resolution. As a proof-of-principle, we show that our sensors can be used for detecting interfacial pH at an electrified platinum nanoparticle-modified carbon electrode during the hydrogen and oxygen evolution reactions. The fast pH sensing capability is expected to open an avenue for routine operando studies of local pH at electrified interfaces.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"25 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653869","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}
The stability of Na-ion cathodes is crucial for the widespread adoption of these sustainable battery technologies. Air stability, a critical factor, impacts the synthesis, storage, electrochemical performance, and safety of cathode materials from laboratory research through to commercial manufacturing. Poor air stability of these cathodes leads to disastrous electrochemical performance. Despite significant advancement in understanding air stability of these materials, a comprehensive strategy to universally enhance the air stability of layered oxides remains undeveloped. Here, we use high-throughput methods to systematically study the impact of substituting Li into 24 different sodium layered oxides. The compositions include all of the currently studied structures such as P2, P3 and O3. From a structural point of view, this substitution is quite facile and generally Li integrates smoothly into the structures. Remarkably, lithium strongly enhances air stability across all 24 compositions as determined from the large set of 96 XRD patterns. The improvement in air stability is thus established as a universal benefit of lithium substitution. While a number of Li-doped samples show lower capacities than in their undoped counterparts, two Li-doped samples demonstrate both improved electrochemical performance and complete air stability under harsh aging conditions.
{"title":"High-throughput study examining the wide benefit of Li substitution in oxide cathodes for Na-ion batteries","authors":"Shipeng Jia, Marzieh Abdolhosseini, Leyth Saglio, Yixuan Li, Marc Kamel, Jean-Danick Lavertu, Stephanie Bazylevych, Valentin Saibi, Pierre-Etienne Cabelguen, Shinichi Kumakura, Eric McCalla","doi":"10.1016/j.electacta.2025.146077","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146077","url":null,"abstract":"The stability of Na-ion cathodes is crucial for the widespread adoption of these sustainable battery technologies. Air stability, a critical factor, impacts the synthesis, storage, electrochemical performance, and safety of cathode materials from laboratory research through to commercial manufacturing. Poor air stability of these cathodes leads to disastrous electrochemical performance. Despite significant advancement in understanding air stability of these materials, a comprehensive strategy to universally enhance the air stability of layered oxides remains undeveloped. Here, we use high-throughput methods to systematically study the impact of substituting Li into 24 different sodium layered oxides. The compositions include all of the currently studied structures such as P2, P3 and O3. From a structural point of view, this substitution is quite facile and generally Li integrates smoothly into the structures. Remarkably, lithium strongly enhances air stability across all 24 compositions as determined from the large set of 96 XRD patterns. The improvement in air stability is thus established as a universal benefit of lithium substitution. While a number of Li-doped samples show lower capacities than in their undoped counterparts, two Li-doped samples demonstrate both improved electrochemical performance and complete air stability under harsh aging conditions.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"293 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653871","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 : 2025-03-19DOI: 10.1016/j.electacta.2025.146080
Luz. E. Rebolledo-Perales, Carlos A. Galán-Vidal, I. Pérez-Silva, Daniel Hernández-Ramírez, Miriam Franco Guzmán, Gabriela Islas, Israel S. Ibarra Ortega, Giaan A. Álvarez Romero
A highly selective ion-imprinted polymer (IIP) was synthesized for the first time, optimized, characterized, and incorporated in a carbon paste electrode (CPE) for As(III) determination in water samples by differential pulse anodic striping voltammetric (DPASV). The As(III)-IIP was prepared considering as functional monomers 2-methyl thiophene and methacrylic acid and ethylene glycol dimethacrylate as a cross-linker, for the As(III) determination, since it is estimated that several people are chronically exposed to arsenic-contaminated water worldwide, therefore a selective and sensitive technique is necessary. A Simplex Centroid Experimental Design was used for the optimization of the IIP synthesis to maximize the anodic peak current (Iap) corresponding to the analytical signal to As(III). The proportions of the composite mixture and the parameters related to the load of the IIP were evaluated, while the DPASV parameters were optimized by a Taguchi design. The higher Iap obtained using the CPE-IIP respect to a single CPE, and a CPE-non-imprinted polymer (NIP), confirms the existence of the recognition cavities of the IIP. Two linear trends were obtained (0.026 to 0.075) mg L−1 and from (17.00 to 700) mg L−1; and a limit of detection (LOD) of 0.007 mg L−1. The proposed electrochemical methodology was successfully applied to determine As(III) in commercial, tap, and dam water samples with and without acid digestion obtaining recovery percentages close to 99.74% suggesting that the digestion pretreatment is not required for this kind of samples. The As-IIP presented the capability to recognize As(III) ions in diverse matrices as demonstrated in the selectivity study.
{"title":"A Novel Voltammetric Methodology Based on a Methacrylic Acid/2-Methyl Thiophene Ion-Imprinted Polymer Sensor for the Determination of As(III) in Water Samples.","authors":"Luz. E. Rebolledo-Perales, Carlos A. Galán-Vidal, I. Pérez-Silva, Daniel Hernández-Ramírez, Miriam Franco Guzmán, Gabriela Islas, Israel S. Ibarra Ortega, Giaan A. Álvarez Romero","doi":"10.1016/j.electacta.2025.146080","DOIUrl":"https://doi.org/10.1016/j.electacta.2025.146080","url":null,"abstract":"A highly selective ion-imprinted polymer (IIP) was synthesized for the first time, optimized, characterized, and incorporated in a carbon paste electrode (CPE) for As(III) determination in water samples by differential pulse anodic striping voltammetric (DPASV). The As(III)-IIP was prepared considering as functional monomers 2-methyl thiophene and methacrylic acid and ethylene glycol dimethacrylate as a cross-linker, for the As(III) determination, since it is estimated that several people are chronically exposed to arsenic-contaminated water worldwide, therefore a selective and sensitive technique is necessary. A Simplex Centroid Experimental Design was used for the optimization of the IIP synthesis to maximize the anodic peak current (Iap) corresponding to the analytical signal to As(III). The proportions of the composite mixture and the parameters related to the load of the IIP were evaluated, while the DPASV parameters were optimized by a Taguchi design. The higher Iap obtained using the CPE-IIP respect to a single CPE, and a CPE-non-imprinted polymer (NIP), confirms the existence of the recognition cavities of the IIP. Two linear trends were obtained (0.026 to 0.075) mg L<sup>−1</sup> and from (17.00 to 700) mg L<sup>−1</sup>; and a limit of detection (LOD) of 0.007 mg L<sup>−1</sup>. The proposed electrochemical methodology was successfully applied to determine As(III) in commercial, tap, and dam water samples with and without acid digestion obtaining recovery percentages close to 99.74% suggesting that the digestion pretreatment is not required for this kind of samples. The As-IIP presented the capability to recognize As(III) ions in diverse matrices as demonstrated in the selectivity study.","PeriodicalId":305,"journal":{"name":"Electrochimica Acta","volume":"29 1","pages":""},"PeriodicalIF":6.6,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660876","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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