Coordination tunes selectivity: two-electron oxygen reduction on high-loading Molybdenum single-atom catalysts

Abstract

Single-atom catalysts (SACs) have great potential in electrocatalysis. Their performance can be rationally optimized by tailoring the center metal atoms, adjacent coordinative dopants, and metal loading. However, it is still of great challenge due to the limited synthesis approach and insufficient understanding of the structure-property relation. Herein, we reported a new kind of Mo SAC with a unique O, S-dual coordination and a high metal loading over 10 wt%. The isolation feature and local environment was identified by high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure. The obtained SACs can catalyze oxygen reduction reaction via 2e- pathway with a high H2O2 selectivity above 95% in 0.10 M KOH. The critical role of Mo single atoms and the coordination structure was revealed by both electrochemical tests and theoretical calculations. This work enriches the family of SACs and highlights the importance of local coordination, thus rendering new opportunities to tune the activity and selectivity in multi-electron electrocatalysis.