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As the global energy landscape shifts toward sustainable hydrogen production, the ethanol oxidation reaction (EOR) has emerged as a superior alternative to the sluggish oxygen evolution reaction. In this study, we connect the spin-state configuration to the catalytic activity of specific metal active sites and synthesize a NiCo2Fe Prussian blue analog (PBA) catalyst with a hollow structure. The NiCo2Fe PBA exhibits exceptional EOR activity, requiring a potential of only 1.30 V vs reversible hydrogen electrode to reach 10 mA cm−2, significantly outperforming most reported non-noble metal catalysts. Mechanistic investigations via density functional theory calculations reveal a dual-functional synergy: (i) the introduction of Ni induces a low-to-intermediate spin-state transition in Co, downshifting its d-band center to optimize the adsorption and desorption of intermediates across the sites and (ii) the incorporated Ni serves as the primary active sites by significantly lowering the energy barrier of the rate-determining step (dehydrogenation of *OCHCH3 to *OCCH3). Furthermore, the catalyst demonstrates robust stability (150 h) and excellent performance in practical applications, including a zinc–ethanol–air battery with a low voltage gap (650 mV) and an anion exchange membrane electrolyzer. This work provides a strategic approach for designing high-performance PBA-based catalysts by integrating specific heteroatom active sites with spin-state engineering.
Tan et al. (Mon,) studied this question.