Amorphization is an efficient strategy to activate intrinsically inert catalysts. However, the low crystallinity of amorphous catalysts often causes high solubility and poor electrochemical stability in aqueous solution. Here, a different mechanism is developed to simultaneously stabilize and activate the water-soluble amorphous MoSx Oy via a charge-balancing strategy, which is induced by different electronegativity between the co-dopants Rh (2.28) and Sn (1.96). The electron-rich Sn prefers to stabilize the unstable apical O sites in MoSx Oy through charge transfer, which can prevent the H from attacking. Meanwhile, the Rh, as the charge regulator, shifts the main active sites on the basal plane from inert Sn to active apical Rh sites. As a result, the amorphous RhSn-MoSx Oy exhibits drastic enhancement in electrochemical stability (η10 increases only by 12 mV) after 1000 cycles and a distinct activity (η10 : 26 mV and Tafel: 30.8 mV dec-1 ) for the hydrogen evolution reaction in acidic solution. This work paves a route for turning impracticably water-soluble catalysts into treasure and inspires new ideas to design high-performance amorphous electrocatalysts.
Keywords: amorphous catalysts; aqueous stability; charge transfer; electronegativity; hydrogen evolution reaction.
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