Pub Date : 2025-01-04DOI: 10.1016/j.jpcs.2025.112556
Hannah Grace G. Necesito , Jonyl L. Garcia , Eric Selorm Dzmarado , Toshihiro Miyao , Junji Inukai , Bernard John V. Tongol
The slow kinetics of the oxygen reduction reaction (ORR) catalyzed by cathode electrocatalysts in fuel cells and metal-air batteries is a major problem. In this study, a composite material consisting of Fe and Co on polypyrrole (PPy)/graphene oxide (GO) support was prepared. The resulting iron-cobalt/polypyrrole/graphene oxide (FeCo/PPy/GO) composite was then pyrolyzed at 900 °C using a tube furnace under N2 atmosphere at a ramp rate of 5 °C min−1 for 1 h. The resulting pyrolyzed electrocatalyst, 900FeCo/PPy/rGO, was characterized using various materials characterization techniques. The effect of pyrolysis temperature (i.e., 800, 900, 1000 °C) of FeCo/PPy/rGO on the ORR activity was investigated using CV and LSV. The 900FeCo/PPy/rGO catalyst composite exhibited the best ORR activity with an onset potential of −0.08 V and a half-wave potential at approximately −0.18 V with an electron transfer number of 3.79, compared to 800FeCo/PPy/rGO and 1000FeCo/PPy/rGO composites. Moreover, the 900FeCo/PPy/rGO catalyst composite showed significantly better electrochemical stability than the benchmark 20 % Pt/C. These results suggest that 900FeCo/PPy/rGO could be a cost-effective substitute for Pt-based ORR electrocatalysts.
{"title":"Pyrolyzed iron–cobalt/polypyrrole/reduced graphene oxide as an effective cathode electrocatalyst for oxygen reduction reaction in an alkaline medium","authors":"Hannah Grace G. Necesito , Jonyl L. Garcia , Eric Selorm Dzmarado , Toshihiro Miyao , Junji Inukai , Bernard John V. Tongol","doi":"10.1016/j.jpcs.2025.112556","DOIUrl":"10.1016/j.jpcs.2025.112556","url":null,"abstract":"<div><div>The slow kinetics of the oxygen reduction reaction (ORR) catalyzed by cathode electrocatalysts in fuel cells and metal-air batteries is a major problem. In this study, a composite material consisting of Fe and Co on polypyrrole (PPy)/graphene oxide (GO) support was prepared. The resulting iron-cobalt/polypyrrole/graphene oxide (FeCo/PPy/GO) composite was then pyrolyzed at 900 °C using a tube furnace under N<sub>2</sub> atmosphere at a ramp rate of 5 °C min<sup>−1</sup> for 1 h. The resulting pyrolyzed electrocatalyst, 900FeCo/PPy/rGO, was characterized using various materials characterization techniques. The effect of pyrolysis temperature (i.e., 800, 900, 1000 °C) of FeCo/PPy/rGO on the ORR activity was investigated using CV and LSV. The 900FeCo/PPy/rGO catalyst composite exhibited the best ORR activity with an onset potential of −0.08 V and a half-wave potential at approximately −0.18 V with an electron transfer number of 3.79, compared to 800FeCo/PPy/rGO and 1000FeCo/PPy/rGO composites. Moreover, the 900FeCo/PPy/rGO catalyst composite showed significantly better electrochemical stability than the benchmark 20 % Pt/C. These results suggest that 900FeCo/PPy/rGO could be a cost-effective substitute for Pt-based ORR electrocatalysts.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112556"},"PeriodicalIF":4.3,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099405","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}
With the continuous development of nano-emerging technologies, silicene nanoribbons, a promising nanostructure for a wide range of applications, have attracted much attention due to their potential applications in electronics and optoelectronics. In this paper, we modelled armchair bilayer silicene nanoribbons (ASiNRs) with widths of 4–15 layers by using the self-consistent charge-density functional tight-binding (SCC-DFTB) method and investigated the effects of geometrical structure and electrical properties of the ASiNRs after adsorption of Si atoms and adsorption of C atoms with an electric field of 0.1 V/nm - 5 V/nm applied on top of the C-atom adsorption. It is found that among the two kinds of atom adsorption, the structure after C atom adsorption is more stable, the bandgap of the structure with a narrower width is opened up more, and a weak electric field of 0.1 V/nm is applied to regulate the bandgap of the nanoribbon more effectively. Whether Si atom adsorption or C atom adsorption, the structure with a narrow width is more likely to exhibit semiconductor properties, the wider the width is, the more metallic it is, and the same is true after applying an electric field. Atom adsorption causes ASiNRs to undergo an obvious charge transfer behaviour. The direction of charge transfer is always from the silicene atoms to the adsorbed atoms, with the adsorbed atoms exhibiting negative electronegativity and the corresponding Si atoms all exhibiting positive electronegativity and the amount of charge transfer is significantly higher for C atom adsorption than for Si atom adsorption.
{"title":"Electronic properties of bilayer silicene nanoribbons modulated by external electric field and carbon adsorption","authors":"Linhan He, Lijun Wu, Shuang Wang, Ziyue Qian, Ya Liu, Longhai Shen","doi":"10.1016/j.jpcs.2024.112531","DOIUrl":"10.1016/j.jpcs.2024.112531","url":null,"abstract":"<div><div>With the continuous development of nano-emerging technologies, silicene nanoribbons, a promising nanostructure for a wide range of applications, have attracted much attention due to their potential applications in electronics and optoelectronics. In this paper, we modelled armchair bilayer silicene nanoribbons (ASiNRs) with widths of 4–15 layers by using the self-consistent charge-density functional tight-binding (SCC-DFTB) method and investigated the effects of geometrical structure and electrical properties of the ASiNRs after adsorption of Si atoms and adsorption of C atoms with an electric field of 0.1 V/nm - 5 V/nm applied on top of the C-atom adsorption. It is found that among the two kinds of atom adsorption, the structure after C atom adsorption is more stable, the bandgap of the structure with a narrower width is opened up more, and a weak electric field of 0.1 V/nm is applied to regulate the bandgap of the nanoribbon more effectively. Whether Si atom adsorption or C atom adsorption, the structure with a narrow width is more likely to exhibit semiconductor properties, the wider the width is, the more metallic it is, and the same is true after applying an electric field. Atom adsorption causes ASiNRs to undergo an obvious charge transfer behaviour. The direction of charge transfer is always from the silicene atoms to the adsorbed atoms, with the adsorbed atoms exhibiting negative electronegativity and the corresponding Si atoms all exhibiting positive electronegativity and the amount of charge transfer is significantly higher for C atom adsorption than for Si atom adsorption.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112531"},"PeriodicalIF":4.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099855","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 : 2025-01-03DOI: 10.1016/j.jpcs.2025.112553
Dan Wang, Jiahui Liu, Jiarui Fang, Xiruo Bai, Yixuan Qie, Run Liu, Tianyu Wang, Chunguang Li, Tianle Lv, Hongyang Tian, Ziheng Li
The molecular adsorption behavior of O2, N2, and H2O on the Al3+ modified SnO2(221) crystal plane and its effect on conductivity were simulated using density functional theory (DFT). The results show that the H2O molecule is chemically adsorbed on the crystal plane as characteristic adsorption species (CAS), forming a surface mode named H2O–SnO2–Al (221). The conductivity of H2O–SnO2–Al (221) is reduced by adsorbing O2 and N2 molecules. The simulation results were confirmed by electrochemical impedance spectroscopy (EIS) under various atmospheric conditions. Using the crystal plane as a humidity sensor to test the different humidity of the air. The results show that the conductivity increases with the rising humidity, which contradicts the results of the H2O single molecule adsorption model. Further FTIR data shows that high humidity on the crystal plane led to the formation of aggregated water, which in turn enhanced both conductivity and capacitance.
{"title":"Study on the adsorption of H2O molecules on Al3+ modified SnO2 (221) crystal plane and the application of humidity sensor","authors":"Dan Wang, Jiahui Liu, Jiarui Fang, Xiruo Bai, Yixuan Qie, Run Liu, Tianyu Wang, Chunguang Li, Tianle Lv, Hongyang Tian, Ziheng Li","doi":"10.1016/j.jpcs.2025.112553","DOIUrl":"10.1016/j.jpcs.2025.112553","url":null,"abstract":"<div><div>The molecular adsorption behavior of O<sub>2</sub>, N<sub>2</sub>, and H<sub>2</sub>O on the Al<sup>3+</sup> modified SnO<sub>2</sub>(221) crystal plane and its effect on conductivity were simulated using density functional theory (DFT). The results show that the H<sub>2</sub>O molecule is chemically adsorbed on the crystal plane as characteristic adsorption species (CAS), forming a surface mode named H<sub>2</sub>O–SnO<sub>2</sub>–Al (221). The conductivity of H<sub>2</sub>O–SnO<sub>2</sub>–Al (221) is reduced by adsorbing O<sub>2</sub> and N<sub>2</sub> molecules. The simulation results were confirmed by electrochemical impedance spectroscopy (EIS) under various atmospheric conditions. Using the crystal plane as a humidity sensor to test the different humidity of the air. The results show that the conductivity increases with the rising humidity, which contradicts the results of the H<sub>2</sub>O single molecule adsorption model. Further FTIR data shows that high humidity on the crystal plane led to the formation of aggregated water, which in turn enhanced both conductivity and capacitance.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112553"},"PeriodicalIF":4.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099858","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 : 2025-01-03DOI: 10.1016/j.jpcs.2025.112555
Sima Darvishi , Samahe Sadjadi , Atieh Rezvanian
A novel covalent triazine framework with sulfonic acid functionality (CTF-SO3H) was synthesized through post-synthetic modification of organic linkers within the CTF using chlorosulfonic acid. The synthesized CTF-SO3H was evaluated as a solid acid nano-catalyst for fructose dehydration to 5-hydroxymethylfurfural (HMF). Optimization using Response Surface Method (RSM) revealed that optimal conditions of 40 wt% catalyst, 110 °C, and 40 min yielded an impressive 97 % HMF in DMSO. The concentration of –SO3H in CTF-SO3H impacted the catalytic activity of CTF-SO3H nano-catalyst and an improvement was found with increasing –SO3H grafting level. Kinetic studies indicated that the CTF–SO3H–mediated fructose-to-HMF dehydration likely follows pseudo-first-order kinetics with a low activation energy of 12 kJ. mol−1 under the studied optimum conditions. Additionally, CTF-SO3H functions as a heterogeneous catalyst, allowing easy recovery and reuse. This research demonstrates the potential of CTF-derived solid acid catalysts for valorizing biomass carbohydrates.
{"title":"Sulfonic acid-functionalized covalent triazine framework as an efficient and reusable nano-catalyst for dehydration of fructose into 5-hydroxymethylfurfural","authors":"Sima Darvishi , Samahe Sadjadi , Atieh Rezvanian","doi":"10.1016/j.jpcs.2025.112555","DOIUrl":"10.1016/j.jpcs.2025.112555","url":null,"abstract":"<div><div>A novel covalent triazine framework with sulfonic acid functionality (CTF-SO<sub>3</sub>H) was synthesized through post-synthetic modification of organic linkers within the CTF using chlorosulfonic acid. The synthesized CTF-SO<sub>3</sub>H was evaluated as a solid acid nano-catalyst for fructose dehydration to 5-hydroxymethylfurfural (HMF). Optimization using Response Surface Method (RSM) revealed that optimal conditions of 40 wt% catalyst, 110 °C, and 40 min yielded an impressive 97 % HMF in DMSO. The concentration of –SO<sub>3</sub>H in CTF-SO<sub>3</sub>H impacted the catalytic activity of CTF-SO<sub>3</sub>H nano-catalyst and an improvement was found with increasing –SO<sub>3</sub>H grafting level. Kinetic studies indicated that the CTF–SO<sub>3</sub>H–mediated fructose-to-HMF dehydration likely follows pseudo-first-order kinetics with a low activation energy of 12 kJ. mol<sup>−1</sup> under the studied optimum conditions. Additionally, CTF-SO<sub>3</sub>H functions as a heterogeneous catalyst, allowing easy recovery and reuse. This research demonstrates the potential of CTF-derived solid acid catalysts for valorizing biomass carbohydrates.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112555"},"PeriodicalIF":4.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099854","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 : 2025-01-02DOI: 10.1016/j.jpcs.2024.112532
Muhammad Imran , Sikandar Azam , Amin Ur Rahman , Muhammad Aamer , Yusuf Siraj Usmani , Muhammad Tahir Khan
The conversion of blue light to white light may now be done more effectively than with non-rare-earth red phosphors (LEDs), It makes it possible to swap out ageing incandescent light bulbs for more energy-efficient light emitting diodes. Yttrium Niobate Y3NbO7: Pr+3, Sm+3 phosphors have a narrow band emission that is brightly red or yellowish-red in color, making it possible to create high-power phosphor-converted LEDs (pc-LED) using this combination. Through analyzing the optoelectronic properties of Y3NbO7 and Y3NbO7: Ln+3 (Ln = Pr, Sm) phosphor compounds, we gained fundamental knowledge of pc-LED activity by computing band gap values using the most recent methodology, density functional theory (DFT). The correlation of the Sm, Pr -f orbitals with the GGA + U was taken into account for the doped Y3NbO7: Ln+3 (Ln = Pr, Sm) material. Throughout the research, we analyzed the electrical characteristics and optical responses of both materials. The parent compound Y3NbO7 band gap is decreased with Pr, Sm doping, resulting in significant absorption at higher energy wavelengths (from blue to green). Additionally, we computed a number of photon energy-related functions, including the complex dielectric function's imaginary and real components, refractive index, absorption coefficient, electron energy loss spectrum, reflectivity, optical conductivity, and extinction coefficient.
{"title":"Ab initio prediction of optoelectronics behavior of Pr+3, Sm+3 doped in novel niobates Y3NbO7 phosphors using GGA+U functional: A study for optoelectronics devices","authors":"Muhammad Imran , Sikandar Azam , Amin Ur Rahman , Muhammad Aamer , Yusuf Siraj Usmani , Muhammad Tahir Khan","doi":"10.1016/j.jpcs.2024.112532","DOIUrl":"10.1016/j.jpcs.2024.112532","url":null,"abstract":"<div><div>The conversion of blue light to white light may now be done more effectively than with non-rare-earth red phosphors (LEDs), It makes it possible to swap out ageing incandescent light bulbs for more energy-efficient light emitting diodes. Yttrium Niobate Y<sub>3</sub>NbO<sub>7</sub>: Pr<sup>+3</sup>, Sm<sup>+3</sup> phosphors have a narrow band emission that is brightly red or yellowish-red in color, making it possible to create high-power phosphor-converted LEDs (pc-LED) using this combination. Through analyzing the optoelectronic properties of Y<sub>3</sub>NbO<sub>7</sub> and Y<sub>3</sub>NbO<sub>7</sub>: Ln<sup>+3</sup> (Ln = Pr, Sm) phosphor compounds, we gained fundamental knowledge of pc-LED activity by computing band gap values using the most recent methodology, density functional theory (DFT). The correlation of the Sm, Pr -f orbitals with the GGA + U was taken into account for the doped Y<sub>3</sub>NbO<sub>7</sub>: Ln<sup>+3</sup> (Ln = Pr, Sm) material. Throughout the research, we analyzed the electrical characteristics and optical responses of both materials. The parent compound Y<sub>3</sub>NbO<sub>7</sub> band gap is decreased with Pr, Sm doping, resulting in significant absorption at higher energy wavelengths (from blue to green). Additionally, we computed a number of photon energy-related functions, including the complex dielectric function's imaginary and real components, refractive index, absorption coefficient, electron energy loss spectrum, reflectivity, optical conductivity, and extinction coefficient.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112532"},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099406","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 : 2025-01-02DOI: 10.1016/j.jpcs.2025.112551
Shakeel Shakeel , Peng Song , Taihong Huang , Syed Hatim Shah , Tao Wang , Khalid M. Alotaibi , Kashif Safeen , Javed Rehman , Wassila Derafa , Muhammad Faizan
Pyrochlore compounds (A2B2O7) have garnered significant importance in materials research due to their distinctive structural, electronic, and thermal properties, making them promising candidates for advanced applications. This study explores the potential of pyrochlore oxides—Nb2Sn2O7, Pr2Hf2O7, Sc2Hf2O7, and Sc2V2O7, through Full Potential Density Functional Theory (FP-DFT), examining their structural, electronic, elastic, and thermodynamic characteristics. The calculated results demonstrate that these compounds possess notable elastic, mechanical, and thermodynamic stability. Among them, Nb2Sn2O7, Pr2Hf2O7, and Sc2V2O7 exhibit metallic behaviors with zero band gaps, whereas Sc2Hf2O7 features an indirect band gap of 1.568 eV, primarily influenced by O-p states. The analysis of elastic and mechanical properties highlights their stable yet anisotropic nature, with a notable tendency towards brittleness. Thermodynamic properties including thermal expansion coefficients, Gibbs free energy, Debye temperature, and specific heat capacity over a temperature range of 200–2000 K were also evaluated using quasi-harmonic Debye approximation. The low thermal conductivity, high thermal expansion comparable to yttria-stabilized zirconia (YSZ) topcoats, and favorable mechanical properties make these compounds ideal candidates for top layers in thermal barrier coatings.
{"title":"Insights into the electronic, mechanical and thermodynamic properties of pyrochlore oxides A2B2O7: A first-principles study","authors":"Shakeel Shakeel , Peng Song , Taihong Huang , Syed Hatim Shah , Tao Wang , Khalid M. Alotaibi , Kashif Safeen , Javed Rehman , Wassila Derafa , Muhammad Faizan","doi":"10.1016/j.jpcs.2025.112551","DOIUrl":"10.1016/j.jpcs.2025.112551","url":null,"abstract":"<div><div>Pyrochlore compounds (A<sub>2</sub>B<sub>2</sub>O<sub>7</sub>) have garnered significant importance in materials research due to their distinctive structural, electronic, and thermal properties, making them promising candidates for advanced applications. This study explores the potential of pyrochlore oxides—Nb<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>, Pr<sub>2</sub>Hf<sub>2</sub>O<sub>7</sub>, Sc<sub>2</sub>Hf<sub>2</sub>O<sub>7</sub>, and Sc<sub>2</sub>V<sub>2</sub>O<sub>7</sub>, through Full Potential Density Functional Theory (FP-DFT), examining their structural, electronic, elastic, and thermodynamic characteristics. The calculated results demonstrate that these compounds possess notable elastic, mechanical, and thermodynamic stability. Among them, Nb<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>, Pr<sub>2</sub>Hf<sub>2</sub>O<sub>7</sub>, and Sc<sub>2</sub>V<sub>2</sub>O<sub>7</sub> exhibit metallic behaviors with zero band gaps, whereas Sc<sub>2</sub>Hf<sub>2</sub>O<sub>7</sub> features an indirect band gap of 1.568 eV, primarily influenced by O-<em>p</em> states. The analysis of elastic and mechanical properties highlights their stable yet anisotropic nature, with a notable tendency towards brittleness. Thermodynamic properties including thermal expansion coefficients, Gibbs free energy, Debye temperature, and specific heat capacity over a temperature range of 200–2000 K were also evaluated using quasi-harmonic Debye approximation. The low thermal conductivity, high thermal expansion comparable to yttria-stabilized zirconia (YSZ) topcoats, and favorable mechanical properties make these compounds ideal candidates for top layers in thermal barrier coatings.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112551"},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099525","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 : 2025-01-02DOI: 10.1016/j.jpcs.2025.112554
Brijmohan Paramanik, Debajyoti Das
The reacting gas pre-heating is presented as a means to enhance the diamond nucleation density in the diamond-like carbon (DLC) films with embedded nanocrystallinity (NCD). Utilizing C2H2 as the precursor gas having low ionization potential, allows for faster NCD-embedded DLC growth. The additions of H2, a conventional dilution gas, along with CO2, a weak oxidant, increase the chemical activity of the growth precursors and aids in the removal of a-C phase from the growth site. Notably, the bandgap widens from 3.40 to 3.48 eV, while the sp3/sp2 ratio increases from 1.9 to 2.38. Raman spectroscopy reveals higher IDia/IG (0.85), IDia/ID (0.94), alongside a lower ID/IG ratio (0.90) for the film grown at the optimum gas-pre-heating temperature (TG = 250 °C) demonstrate the superiority of the less-stressed DLC network, with higher optical transmittance of ∼93% at 600 nm. The DLC matrix developed at a substrate-temperature (TS) ∼300 °C holds a good quality nano-diamond phase (grain size ∼8–10 nm), containing distinct trans-PA peaks (1171 and 1497 cm−1) and diamond peaks (1333 cm−1) as the signature. The preheating of the source gas mixture elevates the precursor gas molecules’ vibrational energy states, facilitating the conversion of C2H2 to CH3, which is energetically favorable for diamond nucleation.
{"title":"Accelerating nanocrystalline-diamond nucleation in the low-temperature MW-CVD growth of diamond-like carbon films via reacting-gas pre-heating","authors":"Brijmohan Paramanik, Debajyoti Das","doi":"10.1016/j.jpcs.2025.112554","DOIUrl":"10.1016/j.jpcs.2025.112554","url":null,"abstract":"<div><div>The reacting gas pre-heating is presented as a means to enhance the diamond nucleation density in the diamond-like carbon (DLC) films with embedded nanocrystallinity (NCD). Utilizing C<sub>2</sub>H<sub>2</sub> as the precursor gas having low ionization potential, allows for faster NCD-embedded DLC growth. The additions of H<sub>2</sub>, a conventional dilution gas, along with CO<sub>2</sub>, a weak oxidant, increase the chemical activity of the growth precursors and aids in the removal of a-C phase from the growth site. Notably, the bandgap widens from 3.40 to 3.48 eV, while the <em>sp</em><sup>3</sup>/<em>sp</em><sup>2</sup> ratio increases from 1.9 to 2.38. Raman spectroscopy reveals higher I<sub>Dia</sub>/I<sub>G</sub> (0.85), I<sub>Dia</sub>/I<sub>D</sub> (0.94), alongside a lower I<sub>D</sub>/I<sub>G</sub> ratio (0.90) for the film grown at the optimum gas-pre-heating temperature (T<sub>G</sub> = 250 °C) demonstrate the superiority of the less-stressed DLC network, with higher optical transmittance of ∼93% at 600 nm. The DLC matrix developed at a substrate-temperature (T<sub>S</sub>) ∼300 °C holds a good quality nano-diamond phase (grain size ∼8–10 nm), containing distinct <em>trans</em>-PA peaks (1171 and 1497 cm<sup>−1</sup>) and diamond peaks (1333 cm<sup>−1</sup>) as the signature. The preheating of the source gas mixture elevates the precursor gas molecules’ vibrational energy states, facilitating the conversion of C<sub>2</sub>H<sub>2</sub> to CH<sub>3</sub>, which is energetically favorable for diamond nucleation.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112554"},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099859","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}
Search for high oxygen-ion conducting electrolyte forms a crucial step towards lowering the operating temperature of conventional solid oxide fuel cell. Here, we report an investigation of conductivity in polycrystalline films of Er and W codoped La1.8Er0.2W0.3Mo1.7O9 (WEr0.2), deposited on four different substrates Si(111), SrTiO3(100), LaAlO3(100) and MgO(100) with different growth orientation and lattice parameters. While all the films show an increase of conductivity by several orders compared to its bulk counterpart, a magnificent increase of about six orders (13 S/cm @ 375 °C) has been observed in films on Si substrate. Films with SrTiO3 and LaAlO3 substrate further show steep rise in conductivity around 450 °C, mimicking the undoped bulk La2Mo2O9 which is triggered by structural phase transition. This large modification of conductivity is believed to be induced by interfacial strain and consequent oxygen vacancy that increases from MgO to Si substrate due to their difference in lattice parameters and growth orientation. The oxygen vacancy concentration calculated using Nernst-Einstein analysis of frequency dependent impedance data further supports an increasing oxygen vacancies in film on Si substrate. The present results show an effective way of tuning conductivity through substrate strain which would hopefully have considerable effect on much sought low temperature operation of fuel cell.
{"title":"Colossal enhancement in ionic conductivity of La2Mo2O9 thin films: Role of lattice strain and oxygen vacancy","authors":"Avinash Patel , Roshan Kumar Patel , A.G.A. Rahman , A.K. Pramanik , Satyendra Singh , Chandrani Nath","doi":"10.1016/j.jpcs.2025.112550","DOIUrl":"10.1016/j.jpcs.2025.112550","url":null,"abstract":"<div><div>Search for high oxygen-ion conducting electrolyte forms a crucial step towards lowering the operating temperature of conventional solid oxide fuel cell. Here, we report an investigation of conductivity in polycrystalline films of Er and W codoped La<sub>1.8</sub>Er<sub>0.2</sub>W<sub>0.3</sub>Mo<sub>1.7</sub>O<sub>9</sub> (WEr0.2), deposited on four different substrates Si(111), SrTiO<sub>3</sub>(100), LaAlO<sub>3</sub>(100) and MgO(100) with different growth orientation and lattice parameters. While all the films show an increase of conductivity by several orders compared to its bulk counterpart, a magnificent increase of about six orders (13 S/cm @ 375 °C) has been observed in films on Si substrate. Films with SrTiO<sub>3</sub> and LaAlO<sub>3</sub> substrate further show steep rise in conductivity around 450 °C, mimicking the undoped bulk La<sub>2</sub>Mo<sub>2</sub>O<sub>9</sub> which is triggered by structural phase transition. This large modification of conductivity is believed to be induced by interfacial strain and consequent oxygen vacancy that increases from MgO to Si substrate due to their difference in lattice parameters and growth orientation. The oxygen vacancy concentration calculated using Nernst-Einstein analysis of frequency dependent impedance data further supports an increasing oxygen vacancies in film on Si substrate. The present results show an effective way of tuning conductivity through substrate strain which would hopefully have considerable effect on much sought low temperature operation of fuel cell.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112550"},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099402","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}
{"title":"Expression of Concern: Investigation of the potential solar cell application of Cs2AgBiBr6 lead-free double perovskite","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112528"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099093","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 : 2025-01-01DOI: 10.1016/j.jpcs.2024.112547
S. Chellaiya Thomas Rueshwin, R.D. Eithiraj
The escalation of global energy demand driven from many factors, leading to dwindling of non-renewable resources and pollution. To mitigate these problems, the thermoelectric systems and photocatalytic hydrogen production are viable solution. The thermoelectric and photocatalytic properties of 1T-Cs2O was investigated theoretically. The physical properties of 1T-Cs2O, WIEN2k software grounded on density functional theory (DFT) is utilized to investigate. Exchange correlation methods, including GGA and hybrid functionals, were implemented to investigate electronic properties, unveiling that 1T-Cs2O is an indirect semiconductor with bandgap values of 0.73 and 1.56 eV, respectively. The dynamical and thermal stability was investigated utilizing the phonon distribution analysis and AIMD calculations. The elastic constants and elastic moduli were calculated. Optical studies revealed that 1T-Cs2O shows a moderate absorption before 10 eV and high absorption after 10 eV. Furthermore, 1T-Cs2O showcased as a potential candidate for thermoelectric systems, at 450 K demonstrating a figure of merit (ZT) of 0.85. The effective masses, relative ratio and the carrier mobilities of charge carriers were assessed. The mobility of the holes and electrons was determined to be 74.72 and 348.50 , respectively. The lattice parameter of 1T-Cs2O is less than the calculated bohr radius and confirms it as Mott-Wannier type semiconductor. 1T-Cs2OThe photocatalytic studies revealed that the 1T-Cs2O is a potential candidate for producing utilizing water splitting.
{"title":"Computational Screening of 2D Cs2O for photocatalysis and thermoelectric properties","authors":"S. Chellaiya Thomas Rueshwin, R.D. Eithiraj","doi":"10.1016/j.jpcs.2024.112547","DOIUrl":"10.1016/j.jpcs.2024.112547","url":null,"abstract":"<div><div>The escalation of global energy demand driven from many factors, leading to dwindling of non-renewable resources and pollution. To mitigate these problems, the thermoelectric systems and photocatalytic hydrogen production are viable solution. The thermoelectric and photocatalytic properties of 1T-Cs<sub>2</sub>O was investigated theoretically. The physical properties of 1T-Cs<sub>2</sub>O, WIEN2k software grounded on density functional theory (DFT) is utilized to investigate. Exchange correlation methods, including GGA and hybrid functionals, were implemented to investigate electronic properties, unveiling that 1T-Cs<sub>2</sub>O is an indirect semiconductor with bandgap values of 0.73 and 1.56 eV, respectively. The dynamical and thermal stability was investigated utilizing the phonon distribution analysis and AIMD calculations. The elastic constants and elastic moduli were calculated. Optical studies revealed that 1T-Cs<sub>2</sub>O shows a moderate absorption before 10 eV and high absorption after 10 eV. Furthermore, 1T-Cs<sub>2</sub>O showcased as a potential candidate for thermoelectric systems, at 450 K demonstrating a figure of merit (ZT) of 0.85. The effective masses, relative ratio and the carrier mobilities of charge carriers were assessed. The mobility of the holes and electrons was determined to be 74.72 <span><math><mrow><msup><mtext>cm</mtext><mn>2</mn></msup><msup><mi>V</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup><msup><mi>s</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> and 348.50 <span><math><mrow><msup><mtext>cm</mtext><mn>2</mn></msup><msup><mi>V</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup><msup><mi>s</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, respectively. The lattice parameter of 1T-Cs<sub>2</sub>O is less than the calculated bohr radius and confirms it as Mott-Wannier type semiconductor. 1T-Cs2OThe photocatalytic studies revealed that the 1T-Cs<sub>2</sub>O is a potential candidate for producing utilizing water splitting.</div></div>","PeriodicalId":16811,"journal":{"name":"Journal of Physics and Chemistry of Solids","volume":"199 ","pages":"Article 112547"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143099279","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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