片状PdPtNiBiCoMo六元金属合金用于高效醇类电氧化

Nanosheet-Like PdPtNiBiCoMo Hexanary Alloy for High-Performance Alcohol Electrooxidation

摘要: 直接乙醇燃料电池(DEFCs)凭借高能量密度、燃料可再生与环境友好等优势成为极具前景的能源转换装置，但其阳极乙醇氧化反应(EOR)动力学迟缓、催化剂易被CO类中间体毒化且长期稳定性不足，传统二元PdPt合金已难以满足综合性能需求。本研究以六羰基钼(Mo(CO)₆)为结构导向剂与温和还原剂，通过一步液相反应成功制备了具有超薄二维片状形貌的PdPtNiBiCoMo六元合金催化剂。该催化剂形成单相面心立方固溶体结构，Pd、Pt、Ni、Bi、Co、Mo六种元素全域均匀分布，无明显偏析。电化学测试表明，其碱性EOR峰值质量活性达3.21 A∙mg⁻¹，分别为商业Pt/C和Pd/C的3.6倍和2.3倍；2000 s计时电流测试后仍保持10倍于商业催化剂的活性，1000次循环伏安测试后活性保留率达65%。同时，该催化剂在甲醇氧化反应(MOR)中也展现出优异性能，峰值质量活性达1.22 A∙mg⁻¹，1000次循环后活性保留率达77%，抗中毒能力与长循环稳定性均远超商业基准催化剂。该工作通过多金属合金化与形貌调控的协同策略，为高性能直接醇类燃料电池阳极催化剂的设计合成提供了新思路。

Abstract: Direct ethanol fuel cells (DEFCs) have emerged as highly promising energy conversion devices owing to their high energy density, fuel renewability, and environmental friendliness. However, the sluggish kinetics of the anodic ethanol oxidation reaction (EOR), susceptibility of catalysts to poisoning by CO-like intermediates, and insufficient long-term stability render conventional binary PdPt alloys inadequate to meet comprehensive performance demands. In this study, using molybdenum hexacarbonyl (Mo(CO)₆) as both a structure-directing agent and a mild reductant, a PdPtNiBiCoMo hexanary alloy catalyst with an ultrathin two-dimensional nanosheet morphology was successfully synthesized via a one-step liquid-phase reaction. The catalyst adopts a single-phase face-centered cubic solid solution structure, with all six elements—Pd, Pt, Ni, Bi, Co, and Mo—uniformly distributed throughout the entire domain without noticeable segregation. Electrochemical evaluations reveal a peak alkaline EOR mass activity of 3.21 A∙mg⁻¹, which is 3.6 and 2.3 times higher than those of commercial Pt/C and Pd/C, respectively. After 2000 s of chronoamperometric testing, the catalyst retains an activity tenfold greater than the commercial benchmarks, and after 1000 cyclic voltammetry cycles, it maintains 65% of its initial activity. Furthermore, the catalyst exhibits outstanding performance in the methanol oxidation reaction (MOR), achieving a peak mass activity of 1.22 A∙mg⁻¹ and retaining 77% activity after 1000 cycles, with anti-poisoning capability and long-term cycling stability far surpassing those of commercial benchmark catalysts. This work, through the synergistic strategy of multi-metal alloying and morphology engineering, provides new insights for the design and synthesis of high-performance anode catalysts for direct alcohol fuel cells.