结合静态模型计算和实验测试,从活化过电势、欧姆损失和浓差过电势三个方面量化分析了阴极Pt负载量和背压协同对质子膜燃料电池(PEMFC)性能的影响规律。考察了阴极Pt负载量为0.1、0.2、0.4 mg?cm^(-2),背压为100、150、200 k Pa条件下...结合静态模型计算和实验测试,从活化过电势、欧姆损失和浓差过电势三个方面量化分析了阴极Pt负载量和背压协同对质子膜燃料电池(PEMFC)性能的影响规律。考察了阴极Pt负载量为0.1、0.2、0.4 mg?cm^(-2),背压为100、150、200 k Pa条件下的燃料电池性能。通过比较发现,在上述条件任意组合下,随着电流密度增加,活化过电势、欧姆损失和浓差过电势逐渐加大,直接影响燃料电池性能;但在相同背压条件下,随着电流密度增加,低Pt负载量时的浓差过电势比高Pt负载量时增加得更快;同时发现,背压增加对提高燃料电池的性能有帮助,但背压增加对低Pt负载量比对高Pt负载量效果更明显。因此对于低Pt燃料电池,应适当提高运行背压以优化其性能。本文对上述实验结果的产生机理进行了探讨,并期望该结果能对低Pt/超低Pt燃料电池的设计及性能优化提供参考与借鉴。展开更多
Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting th...Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting the durability of the fuel cells. Meanwhile, carbon corrosion would also weaken the linkage between Pt and the support material, which causes Pt agglomeration, and consequently, deterioration of the cell performance. To overcome the drawbacks of a Pt/C electrocatalyst, a hybrid support material comprising molybdenum disulfide and reduced graphene oxide is proposed and synthesized in this study to exploit the graphitic nature of graphene and the availability of the exposed edges of MoS2. TEM results show the uniform dispersion of Pt nanoparticles over the MoS2-rGO surface. Electrochemical measurements indicate higher ECSA retention and better ORR activity after 10000 potential cycles for Pt/MoS2-rGO as compared to Pt/C, demonstrating the improved durability for this hybrid support material.展开更多
In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co at...In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co atoms that present the higher d band center are marked as valid sites,whereas the others are marked as invalid sites owing to their weaker H adsorption ability.It is further revealed that W-doping can decrease the d band center of the surface Co atoms,which is beneficial for the HER;however the exposure to W weakens the desorption of H.To address the strong adsorption effect of W,the doping sites and dopant content are analyzed,and the results indicate that 8.4 wt%W doping at the invalid surface Co sites is preferred;moreover,the optimal W content increases to 16.8 wt%when W is inserted into the subsurface.The effect of W doping is weakened when the doping site is far away from the surface.展开更多
In this work,highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide(DMF).A series of carbo...In this work,highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide(DMF).A series of carbon supported Pt-Ni alloy electrocatalysts were synthesized under different applied electrode potentials.Among all as-obtained samples,the Pt-Ni/C electrocatalyst deposited at-1.73 V exhibits the optimal specific activity up to 1.850 mA cm^(-2)at 0.9 V vs.RHE,which is 6.85 times higher than that of the commercial Pt/C.Comprehensive physiochemical characterizations and computational evaluations via density functional theory were conducted to unveil the nucleation and growth mechanism of PtNi alloy formation.Compared to the aqueous solution,DMF solvent molecule must not be neglected in avoiding particle agglomeration and synthesis of monodispersed nanoparticles.During the alloy co-deposition process,Ni sites produced through the reduction of Ni(Ⅱ)precursor not only facilitates Pt-Ni alloy crystal nucleation but also in favor of further Pt reduction on the Ni-inserted Pt surface.As for the deposition potential,it adjusts the final particle size.This work provides a hopeful extended Pt-based catalyst layer production strategy for proton exchange membrane fuel cells and a new idea for the nucleation and growth mechanism exploration for electrodeposited Pt alloy.展开更多
文摘结合静态模型计算和实验测试,从活化过电势、欧姆损失和浓差过电势三个方面量化分析了阴极Pt负载量和背压协同对质子膜燃料电池(PEMFC)性能的影响规律。考察了阴极Pt负载量为0.1、0.2、0.4 mg?cm^(-2),背压为100、150、200 k Pa条件下的燃料电池性能。通过比较发现,在上述条件任意组合下,随着电流密度增加,活化过电势、欧姆损失和浓差过电势逐渐加大,直接影响燃料电池性能;但在相同背压条件下,随着电流密度增加,低Pt负载量时的浓差过电势比高Pt负载量时增加得更快;同时发现,背压增加对提高燃料电池的性能有帮助,但背压增加对低Pt负载量比对高Pt负载量效果更明显。因此对于低Pt燃料电池,应适当提高运行背压以优化其性能。本文对上述实验结果的产生机理进行了探讨,并期望该结果能对低Pt/超低Pt燃料电池的设计及性能优化提供参考与借鉴。
基金funded by the National Key Research and Development Program of China(No.2016YFB0101201)the National Natural Science Foundation of China (No.21533005 and No. 21503134).
基金supported by the National Natural Science Foundation of China(21373135)Science Foundation of Ministry of Education of China(413064)and Program of Introducing Talents of Discipline to Universities,China("111 Project")(B13018)~~
基金financially aided by the National Key R&D Program of China(2016YFB0101201)the National Natural Science Foundation of China(21706158,21533005)~~
文摘Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting the durability of the fuel cells. Meanwhile, carbon corrosion would also weaken the linkage between Pt and the support material, which causes Pt agglomeration, and consequently, deterioration of the cell performance. To overcome the drawbacks of a Pt/C electrocatalyst, a hybrid support material comprising molybdenum disulfide and reduced graphene oxide is proposed and synthesized in this study to exploit the graphitic nature of graphene and the availability of the exposed edges of MoS2. TEM results show the uniform dispersion of Pt nanoparticles over the MoS2-rGO surface. Electrochemical measurements indicate higher ECSA retention and better ORR activity after 10000 potential cycles for Pt/MoS2-rGO as compared to Pt/C, demonstrating the improved durability for this hybrid support material.
文摘In this study,we investigated the hydrogen evolution reaction(HER)on the(101)facet of pristine and W-doped CoP using the density functional theory.Two types of Co atoms are identified on the catalyst surface:the Co atoms that present the higher d band center are marked as valid sites,whereas the others are marked as invalid sites owing to their weaker H adsorption ability.It is further revealed that W-doping can decrease the d band center of the surface Co atoms,which is beneficial for the HER;however the exposure to W weakens the desorption of H.To address the strong adsorption effect of W,the doping sites and dopant content are analyzed,and the results indicate that 8.4 wt%W doping at the invalid surface Co sites is preferred;moreover,the optimal W content increases to 16.8 wt%when W is inserted into the subsurface.The effect of W doping is weakened when the doping site is far away from the surface.
文摘In this work,highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide(DMF).A series of carbon supported Pt-Ni alloy electrocatalysts were synthesized under different applied electrode potentials.Among all as-obtained samples,the Pt-Ni/C electrocatalyst deposited at-1.73 V exhibits the optimal specific activity up to 1.850 mA cm^(-2)at 0.9 V vs.RHE,which is 6.85 times higher than that of the commercial Pt/C.Comprehensive physiochemical characterizations and computational evaluations via density functional theory were conducted to unveil the nucleation and growth mechanism of PtNi alloy formation.Compared to the aqueous solution,DMF solvent molecule must not be neglected in avoiding particle agglomeration and synthesis of monodispersed nanoparticles.During the alloy co-deposition process,Ni sites produced through the reduction of Ni(Ⅱ)precursor not only facilitates Pt-Ni alloy crystal nucleation but also in favor of further Pt reduction on the Ni-inserted Pt surface.As for the deposition potential,it adjusts the final particle size.This work provides a hopeful extended Pt-based catalyst layer production strategy for proton exchange membrane fuel cells and a new idea for the nucleation and growth mechanism exploration for electrodeposited Pt alloy.
