【摘要】 直接甲醇燃料电池（DMFC）是一种先进的可持续能源转换技术,其燃料甲醇的能量密度高达6.13 kW h kg^-1且与我国现有的燃料基础设施具有较强的兼容性.然而, DMFC实际应用仍受限于两大关键瓶颈:缓慢的甲醇氧化反应（MOR）动力学和较差的稳定性.这迫使当前体系需使用高载量(>2 mg cm^-2)且昂贵的PtRu基催化剂,却仅能提供不足80 mW cm^-2的功率密度,严重制约了DMFC的商业化落地应用.为实现质子交换膜型DMFC的高功率和低铂化目标,本研究在铂锌纳米颗粒表面构建原子级分散的氧化态钌（RuO_x）物种作为高效水活化中心,以协同促进MOR过程.通过锌的电子调控作用,钌物种趋于稳定的+2价态,显著增强了界面水分子的捕获与解离能力,并促进吸附态的羟基自由基（*OH）向相邻铂位点的迁移,从而实现了相邻铂位点上一氧化碳吸附物的快速脱除. RuO_x-PtZn催化剂在三电极测试体系中展现出卓越的MOR质量活性,达到2.71 A mgPt^-1,较商业Pt/C提升3.7倍;将其作为阳极催化剂组装的DMFC实现了191.2 mW cm^-2的峰值功率密度,同时保持了125 h的稳定性.为深入理解其高性能机制,本文结合第一性原理分子动力学模拟和电化学原位傅里叶变换红外光谱,发现钌中心周围形成了以氧端朝下（O-down）方式排列的致密水分子网络.该结构有效促进了界面水捕获,并经由关键中间体RuO（OH）₂的形成显著降低水解离能垒.动力学同位素效应测试（CH₃OH/H₂O vs. CH₃OH/D₂O）显示,在0.85 V vs. RHE电位下, RuO_x-PtZn/C催化剂的J_H2O/D2O比值为4.2,而RuO_x-Pt/C的比值高达16.2,这直接证实了RuO_x-PtZn/C具有卓越的水活化效率,与密度泛函理论计算水活化过渡态的结果一致.差分电化学原位质谱结果表明,该催化剂在较低过电位下即可完成6电子转移过程,显著提升了甲醇完全电氧化的反应动力学.综上,本研究通过实验与理论相结合的方法,系统阐释了RuO_x-PtZn/C催化剂在甲醇电氧化反应中的协同促进机制,不仅为设计高效稳定的MOR催化剂提供了新思路,也为推动DMFC的实际应用奠定了理论与技术基础.更多还原

【Abstract】 For achieving high-power and low-platinum direct methanol fuel cell （DMFC） under proton-exchange-membrane,we introduce the oxidation-state ruthenium species as H₂O-activation centers stabilized on PtZn NPs to boost methanol-oxidation reaction （MOR）.The Zn-regulated Ru centers,approaching bivalent states,enhance interfacial H₂O-capture/dissociation and OH-transfer,enabling rapid CO*removal from adjacent Pt sites.It exhibits an outstanding mass activity of MOR at 2.71 A mg _Pt^–1 and powers a DMFC with 191.2 mW cm^–2 peak density (382.4 W g _Pt^–1) while maintaining 125-hour stability,higher than documented results to date,essentially different from traditional alloy catalysts.Combined ab initio molecular dynamics simulations and in-situ spectroscopy reveal a dense O-down water network around Ru centers,where intermediate RuO（OH）₂ structure significantly deceases the H₂O-dissociation barrier.Kinetic isotope effect tests （CH₃OH/H₂O vs.D₂O）show J_H2O/D2O=4.2 for RuO_x-PtZn/C at 0.85 V_RHE,versus 16.2 for RuO_x-Pt/C,directly confirming superior water activation efficiency of RuO_x-Pt Zn/C.We envision that the comprehensive understanding of high-performance MOR on RuO_x-PtZn/C through experimental-theoretical approaches will contribute to the practical application of DMFC as early as possible.更多还原