Modulating electronic structure of CoP electrocatalysts towards enhanced hydrogen evolution by Ce chemical doping in both acidic and basic media

Doping foreign metal ions into catalysts is considered as an effective approach to optimize the catalytic sites and improve their performance. Here, we develop and demonstrate the concept of rare-earth elemental doping by Ce into host catalysts of CoP in modulating their electronic structures and decreasing their adsorption free energy of hydrogen for the enhanced hydrogen evolution reaction (HER) performance via a complementary theoretical and experimental approach. In contrast to undoped catalysts, the Ce-doping can facilitate lower overpotential, Tafel slope and charge transfer resistance as well as larger electrochemically active surface area and turnover frequency to deliver superb catalytic activity and stability. In particular, the catalyst with optimized doping amount exhibits ultra-low overpotentials of 54 and 92 mV at 10 mA cm⁻² in acidic and basic media, respectively, among many recently-reported CoP-based catalysts. Doping Ce into CoP not only illustrates benefits in improving the catalytic property for HER, but also opens up a novel view of doping rare earth elements into electrocatalysts for regulating their physiochemical and electrochemical properties.