Tailoring the Electronic Structure of an Atomically Dispersed Zinc Electrocatalyst: Coordination Environment Regulation for High Selectivity Oxygen Reduction.

Accurately regulating the selectivity of the oxygen reduction reaction (ORR) is crucial to renewable energy storage and utilization, but challenging. A flexible alteration of ORR pathways on atomically dispersed Zn sites towards high selectivity ORR can be achieved by tailoring the coordination environment of the catalytic centers. The atomically dispersed Zn catalysts with unique O- and C-coordination structure (ZnO C) or N-coordination structure (ZnN ) can be prepared by varying the functional groups of corresponding MOF precursors. The coordination environment of as-prepared atomically dispersed Zn catalysts was confirmed by X-ray absorption fine structure (XAFs). Notably, the ZnN catalyst processes a 4 e ORR pathway to generate H O. However, controllably tailoring the coordination environment of atomically dispersed Zn sites, ZnO C catalyst processes a 2 e ORR pathway to generate H O with a near zero overpotential and high selectivity in 0.1 M KOH. Calculations reveal that decreased electron density around Zn in ZnO C lowers the d-band center of Zn, thus changing the intermediate adsorption and contributing to the high selectivity towards 2 e ORR.