Mesoporous carbon supports mitigate platinum(Pt)sulfonic poisoning through nanopore-confined Pt deposition,yet their morphological impacts on oxygen transport remain unclear.This study integrates carbon support morpho...Mesoporous carbon supports mitigate platinum(Pt)sulfonic poisoning through nanopore-confined Pt deposition,yet their morphological impacts on oxygen transport remain unclear.This study integrates carbon support morphology simulation with an enhanced agglomerate model to establish a mathematical framework elucidating pore evolution,Pt utilization,and oxygen transport in catalyst layers.Results demonstrate dominant local mass transport resistance governed by three factors:(1)active site density dictating oxygen flux;(2)ionomer film thickness defining shortest transport path;(3)ionomer-to-Pt surface area ratio modulating practical pathway length.At low ionomer-to-carbon(I/C)ratios,limited active sites elevate resistance(Factor 1 dominant).Higher I/C ratios improve the ionomer coverage but eventually thicken ionomer films,degrading transport(Factors 2–3 dominant).The results indicate that larger carbon particles result in a net increase in local transport resistance by reducing external surface area and increasing ionomer thickness.As the proportion of Pt situated in nanopores or the Pt mass fraction increases,elevated Pt density inside the nanopores exacerbates pore blockage.This leads to the increased transport resistance by reducing active sites,and increasing ionomer thickness and surface area.Lower Pt loading linearly intensifies oxygen flux resistance.The model underscores the necessity to optimize support morphology,Pt distribution,and ionomer content to prevent pore blockage while balancing catalytic activity and transport efficiency.These insights provide a systematic approach for designing high-performance mesoporous carbon catalysts.展开更多
分析了"自呼吸式"直接甲醇燃料电池膜电极性能衰减的因素及其影响程度。通过对膜电极进行2 000 h恒电流(25 m A/cm2)放电,对比了放电前后的极化曲线、交流阻抗谱及电化学活性面积。恒电流放电后,膜电极的最大功率密度从初始的...分析了"自呼吸式"直接甲醇燃料电池膜电极性能衰减的因素及其影响程度。通过对膜电极进行2 000 h恒电流(25 m A/cm2)放电,对比了放电前后的极化曲线、交流阻抗谱及电化学活性面积。恒电流放电后,膜电极的最大功率密度从初始的29.1 m W/cm2下降到21.8 m W/cm2,开路电压基本不变;交流阻抗谱定量分析表明,阴极的电阻明显大于阳极,并且对膜电极性能衰减的影响程度是:阴极>>阳极>质子交换膜;循环伏安测试显示阴极催化剂电化学活性面积的衰减为21%,明显大于阳极催化剂的衰减2%。展开更多
基金supported by the Program of Ministry of Science and Technology of China(No.2023YFB2504200)support of Shanghai Rising-Star Program(Grant No.24QB2703200)the Major Science and Technology Projects of Yunnan Province(No.202302AH360001).
文摘Mesoporous carbon supports mitigate platinum(Pt)sulfonic poisoning through nanopore-confined Pt deposition,yet their morphological impacts on oxygen transport remain unclear.This study integrates carbon support morphology simulation with an enhanced agglomerate model to establish a mathematical framework elucidating pore evolution,Pt utilization,and oxygen transport in catalyst layers.Results demonstrate dominant local mass transport resistance governed by three factors:(1)active site density dictating oxygen flux;(2)ionomer film thickness defining shortest transport path;(3)ionomer-to-Pt surface area ratio modulating practical pathway length.At low ionomer-to-carbon(I/C)ratios,limited active sites elevate resistance(Factor 1 dominant).Higher I/C ratios improve the ionomer coverage but eventually thicken ionomer films,degrading transport(Factors 2–3 dominant).The results indicate that larger carbon particles result in a net increase in local transport resistance by reducing external surface area and increasing ionomer thickness.As the proportion of Pt situated in nanopores or the Pt mass fraction increases,elevated Pt density inside the nanopores exacerbates pore blockage.This leads to the increased transport resistance by reducing active sites,and increasing ionomer thickness and surface area.Lower Pt loading linearly intensifies oxygen flux resistance.The model underscores the necessity to optimize support morphology,Pt distribution,and ionomer content to prevent pore blockage while balancing catalytic activity and transport efficiency.These insights provide a systematic approach for designing high-performance mesoporous carbon catalysts.
文摘分析了"自呼吸式"直接甲醇燃料电池膜电极性能衰减的因素及其影响程度。通过对膜电极进行2 000 h恒电流(25 m A/cm2)放电,对比了放电前后的极化曲线、交流阻抗谱及电化学活性面积。恒电流放电后,膜电极的最大功率密度从初始的29.1 m W/cm2下降到21.8 m W/cm2,开路电压基本不变;交流阻抗谱定量分析表明,阴极的电阻明显大于阳极,并且对膜电极性能衰减的影响程度是:阴极>>阳极>质子交换膜;循环伏安测试显示阴极催化剂电化学活性面积的衰减为21%,明显大于阳极催化剂的衰减2%。
