Building multi-active sites in PtPdRuCuNi high-entropy alloy aerogels for pH-general electrochemical methanol oxidation reaction and direct methanol fuel cells.

The development of high-performance carbon-free Pt-based electrocatalysts that combine exceptional methanol oxidation activity with robust CO-poisoning resistance remained a significant challenge in fuel cell technology. Herein, we presented a new class of PtPdRuCuNi alloy aerogel electrocatalyst, featuring a structurally unique hollow network architecture with nanoporous ligaments (average diameter: 5.16 nm). The optimized catalyst exhibited remarkable mass activities of 2.05, 1.37, and 4.50 A mgPt-1 in acidic, neutral, and alkaline methanol oxidation environments, respectively, surpassing the performance of commercial PtRu/C (0.74, 1.00, 2.06 A mgPt-1). The CO oxidation peak potential exhibited a substantial 172 mV negative shift (0.352 V vs SCE) compared to conventional Pt/C (0.524 V). In-situ FTIR analysis uncovered a distinctive reaction pathway in which formic acid emerged as the primary intermediate during methanol oxidation processes at high potentials and successfully bypassed the conventional CO-mediated poisoning mechanism prevalent in Pt-based catalysts. When employed as an anode catalyst in DMFC, the alloy aerogel delivered a power density of 77.7 mW cm-2 at 65 °C, the mass-specific power attained a remarkable 109.7 mW mgPt-1 at Pt loading of 0.37 mg cm-2. This work introduced a new paradigm for carbon-free Pt-alloy catalyst design by leveraging alloy synergy and nanostructural engineering.