Molybdenum carbide/molybdenum nitride hybrid N-doped graphene （abbreviated as Mo2C/MoN/NG）, as an efficient electrocatalyst for the hydrogen evolution reaction （HER）, was synthesized via simple ion-exchange resin ...Molybdenum carbide/molybdenum nitride hybrid N-doped graphene （abbreviated as Mo2C/MoN/NG）, as an efficient electrocatalyst for the hydrogen evolution reaction （HER）, was synthesized via simple ion-exchange resin synthesis followed by a two-step annealing process, which increased the dispersion degree of the electrocatalyst＇s active sites on the support skeleton and simplified the synthetic conditions. Additionally, N-doped graphene （NG） enhanced the electron transfer and reduced the inner resistance. The material has a graphene-like morphology and highly dispersed Mo2C/MoN nanoparticles about 2 nm in diameter on the NG. X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy revealed that Mo2C/MoN/NG consisted of Mo2C and MoN composited together. Finally, Mo2C/MoN/NG exhibited remarkable performance as an electrocatalyst for the HER with a small overpotential of 78.82 mV and a small Tafel slope of 39.3 mV.dec^-1 in a 0.5 mol.L-1 H2SO4 solution. Its activity was approximately 30% lower than that of 20% Pt/C and 60% higher than that of NG. Also, it exhibited a low onset overpotential of 24.82 mV, which is similar to the theoretical HER potential. Our work provides a foundation for advanced HER applications of molybdenum compounds.展开更多
The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to prod...The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to produce high purity hydrogen. Cobalt-based catalysts are well-known electrocatalysts for oxygen evolution reaction（OER）. In this article, all these merits indicate that the present cobalt nanocomposite is a promising electrocatalyst for OER. C–CoO-nanorods catalyst with nanorod structure was synthesized by hydrothermal treatment of CoCl·6HO/dextrose/urea mixture at 180 °C for 18 h and then calcined at400 °C for 3.5 h. The role of dextrose percentage in solution to achieve the uniform coating of carbon on the surface of CoO-nanorods has been demonstrated. The prepared materials were characterized by X-ray diffraction（XRD）, X-ray photoelectron spectrum（XPS）, field emission scanning electron microscopy（FE-SEM）, high-resolution transmission electron microscopy（HR-TEM）, and Brunauer–Emmett–Teller instrument（BET）. Due to its unique morphology, the C–CoO-nanorods catalyst exhibited better activity than CoO-microplates catalyst for OER in 1 M KOH aqueous solution. The results showed a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.展开更多
The synthesis of non-metal carbon catalysts with high catalytic activity for ORR(oxygen reduction reaction)in acidic media is a great challenge in the field of PEMFC(proton exchange membrane fuel cells).In this resear...The synthesis of non-metal carbon catalysts with high catalytic activity for ORR(oxygen reduction reaction)in acidic media is a great challenge in the field of PEMFC(proton exchange membrane fuel cells).In this research,N-and F-codoped carbon catalyst with high performance was synthesized from ZIF-8 and NH4F,which are easily prepared structure and common chemical,respectively.The as-prepared catalyst has a high surface area of 789 m2/g and micro-porosity of~2 nm,facilitating more active sites to the ORR and O2 mass transfer in the diffusion of the catalyst matrix,respectively.The prepared N/C(NH4F)catalyst exhibited an onset potential of 0.94 V(vs.RHE)and a half-wave potential of 0.65 V in 0.1 M HClO4 solution.It also showed excellent durability in the cycling test of 10,000 times and a degradation shift of half-wave potential 70 mV was observed.Its diffusion-limiting current reached 5.85 mA/cm2 next to the theoretic value of 6 mA/cm2,suggesting that it has plenty of active sites for ORR,which could be attributed to fluorine introduction into the N/C catalyst.It proved that the introduction of fluorine into the structure of the N/C catalyst fine-tunes the Lewis basic sites of the carbon atoms adjacent to pyridinic and graphitic nitrogen species,facilitating the adsorption of oxygen molecules in the initial step of the ORR.The correlation between the N/C catalyst activity and the fluorination provides new insight into the ORR catalyst design.展开更多
以NaH_2PO_2和Ni_2SO_4为磷源和镍源,使用一锅法合成了非晶态NiP合金及其碳纳米(乙炔黑和石墨烯)复合催化剂。用透射电子显微镜(TEM)、X射线衍射仪(XRD)、热重分析(TGA)、电感耦合等离子体光谱仪(ICP)分别对催化剂性能和组成进行了表征...以NaH_2PO_2和Ni_2SO_4为磷源和镍源,使用一锅法合成了非晶态NiP合金及其碳纳米(乙炔黑和石墨烯)复合催化剂。用透射电子显微镜(TEM)、X射线衍射仪(XRD)、热重分析(TGA)、电感耦合等离子体光谱仪(ICP)分别对催化剂性能和组成进行了表征和分析。通过线性扫描伏安对催化剂在酸性和碱性条件下的析氢性能进行了评价,研究结果表明,非晶态NiP/还原氧化石墨烯复合催化剂(NiP/RGO)展现出优异的电催化性能。在0.5 mol/L H_2SO_4中的起始过电位为89.0 m V,塔菲尔斜率为135.1 m V/decade;在1 mol/L NaOH中,起始过电位为116.1 m V,塔菲尔斜率为122.4 m V/decade,这与商业化Pt黑催化剂很接近。500次循环以后,催化剂活性没有明显下降,表明该催化剂具有良好的稳定性。该研究提供了一种简单可行的制备非贵金属磷化物方法用于电催化析氢反应。展开更多
文摘Molybdenum carbide/molybdenum nitride hybrid N-doped graphene （abbreviated as Mo2C/MoN/NG）, as an efficient electrocatalyst for the hydrogen evolution reaction （HER）, was synthesized via simple ion-exchange resin synthesis followed by a two-step annealing process, which increased the dispersion degree of the electrocatalyst＇s active sites on the support skeleton and simplified the synthetic conditions. Additionally, N-doped graphene （NG） enhanced the electron transfer and reduced the inner resistance. The material has a graphene-like morphology and highly dispersed Mo2C/MoN nanoparticles about 2 nm in diameter on the NG. X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy revealed that Mo2C/MoN/NG consisted of Mo2C and MoN composited together. Finally, Mo2C/MoN/NG exhibited remarkable performance as an electrocatalyst for the HER with a small overpotential of 78.82 mV and a small Tafel slope of 39.3 mV.dec^-1 in a 0.5 mol.L-1 H2SO4 solution. Its activity was approximately 30% lower than that of 20% Pt/C and 60% higher than that of NG. Also, it exhibited a low onset overpotential of 24.82 mV, which is similar to the theoretical HER potential. Our work provides a foundation for advanced HER applications of molybdenum compounds.
基金Natural Science Foundation of Shanxi(201901D111310,201801D221057)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province(2020L0478,2021L388)Natural Science Foundation of Datong(2019160).
基金supported by the National Research Foundation of Korea(NRF)–Grants funded by the Ministry of Science,ICT and Future Planning(2014R1A2A2A01004352),Republic of Korea
文摘The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to produce high purity hydrogen. Cobalt-based catalysts are well-known electrocatalysts for oxygen evolution reaction（OER）. In this article, all these merits indicate that the present cobalt nanocomposite is a promising electrocatalyst for OER. C–CoO-nanorods catalyst with nanorod structure was synthesized by hydrothermal treatment of CoCl·6HO/dextrose/urea mixture at 180 °C for 18 h and then calcined at400 °C for 3.5 h. The role of dextrose percentage in solution to achieve the uniform coating of carbon on the surface of CoO-nanorods has been demonstrated. The prepared materials were characterized by X-ray diffraction（XRD）, X-ray photoelectron spectrum（XPS）, field emission scanning electron microscopy（FE-SEM）, high-resolution transmission electron microscopy（HR-TEM）, and Brunauer–Emmett–Teller instrument（BET）. Due to its unique morphology, the C–CoO-nanorods catalyst exhibited better activity than CoO-microplates catalyst for OER in 1 M KOH aqueous solution. The results showed a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.
基金supported by Projects of Talents Recruitment and PhDs’Start-up Research of GDUPT,Guangdong Province Science and Technology Innovation Strategic Project (2023S005049)Guangdong Basic and Applied Basic Research Foundation (2022A1515011927)Characteristic Innovation Foundation of Guangdong Province (2020KTSCX082).
文摘The synthesis of non-metal carbon catalysts with high catalytic activity for ORR(oxygen reduction reaction)in acidic media is a great challenge in the field of PEMFC(proton exchange membrane fuel cells).In this research,N-and F-codoped carbon catalyst with high performance was synthesized from ZIF-8 and NH4F,which are easily prepared structure and common chemical,respectively.The as-prepared catalyst has a high surface area of 789 m2/g and micro-porosity of~2 nm,facilitating more active sites to the ORR and O2 mass transfer in the diffusion of the catalyst matrix,respectively.The prepared N/C(NH4F)catalyst exhibited an onset potential of 0.94 V(vs.RHE)and a half-wave potential of 0.65 V in 0.1 M HClO4 solution.It also showed excellent durability in the cycling test of 10,000 times and a degradation shift of half-wave potential 70 mV was observed.Its diffusion-limiting current reached 5.85 mA/cm2 next to the theoretic value of 6 mA/cm2,suggesting that it has plenty of active sites for ORR,which could be attributed to fluorine introduction into the N/C catalyst.It proved that the introduction of fluorine into the structure of the N/C catalyst fine-tunes the Lewis basic sites of the carbon atoms adjacent to pyridinic and graphitic nitrogen species,facilitating the adsorption of oxygen molecules in the initial step of the ORR.The correlation between the N/C catalyst activity and the fluorination provides new insight into the ORR catalyst design.
基金supported by National Natural Science Foundation of China(21073113)Natural Science Foundation of Shanxi(201701D121016)+1 种基金Science,Technology Innovation Project of Shanxi Province University(2015178,2016172)Natural Science Foundortion of Datong(2015108)
文摘以NaH_2PO_2和Ni_2SO_4为磷源和镍源,使用一锅法合成了非晶态NiP合金及其碳纳米(乙炔黑和石墨烯)复合催化剂。用透射电子显微镜(TEM)、X射线衍射仪(XRD)、热重分析(TGA)、电感耦合等离子体光谱仪(ICP)分别对催化剂性能和组成进行了表征和分析。通过线性扫描伏安对催化剂在酸性和碱性条件下的析氢性能进行了评价,研究结果表明,非晶态NiP/还原氧化石墨烯复合催化剂(NiP/RGO)展现出优异的电催化性能。在0.5 mol/L H_2SO_4中的起始过电位为89.0 m V,塔菲尔斜率为135.1 m V/decade;在1 mol/L NaOH中,起始过电位为116.1 m V,塔菲尔斜率为122.4 m V/decade,这与商业化Pt黑催化剂很接近。500次循环以后,催化剂活性没有明显下降,表明该催化剂具有良好的稳定性。该研究提供了一种简单可行的制备非贵金属磷化物方法用于电催化析氢反应。
