Single-atom catalysts (SACs) have great potential in electrocatalysis. Their performance can be rationally optimized by tailoring the metal atoms, adjacent coordinative dopants, and metal loading. However, doing so is still a great challenge because of the limited synthesis approach and insufficient understanding of the structure-property relationships. Herein, we report a new kind of Mo SAC with a unique O,S coordination and a high metal loading over 10 wt %. The isolation and local environment was identified by high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure. The SACs catalyze the oxygen reduction reaction (ORR) via a 2 e- pathway with a high H2 O2 selectivity of over 95 % in 0.10 m KOH. The critical role of the Mo single atoms and the coordination structure was revealed by both electrochemical tests and theoretical calculations.
Keywords: electrocatalysis; molybdenum; oxygen reduction reaction (ORR); selectivity; single-atom catalyst.
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