Low-Coordinated Mo Clusters for High-Efficiency Electrocatalytic Hydrogen Peroxide Production

Electrocatalytic oxygen reduction reaction (ORR) to generate hydrogen peroxide (H2O2) via a 2e(-) pathway offers a green alternative to the energy-extensive anthraquinone process; however, the challenge lies in the development of low cost and effective 2e(-) ORR catalysts. In this work, a highly selective and stable Mo clusters supported by nitrogen-doped carbon polyhedrons catalyst for direct H2O2 electrosynthesis are first designed, which shows a high H2O2 selectivity (>77%) in the applied potential range varying from 0.2 to 0.65 V vs RHE, and an excellent mass activity of 29.0 A g(cat.)(-1) (at 0.65 V) with negligible activity decay over 10000 cycles in an alkaline medium. Moreover, the catalyst displays a yield rate of 136.2 +/- 1.5 ppm cm(-2) h(-1) at -20 mA cm(-2) in a continuous flow cell with neutral electrolyte. Taken together, the obtained performance metrics are comparable to the best-reported ORR results. Density-functional theory analyses reveal that Mo clusters can donor electrons to activate O-2 molecules and strengthen the *OOH binding on Mo sites as well, thus inducing a high H2O2 selectivity. The present work provides a unique insight into the atomic introduction of metal clusters-based materials for 2e(-) ORR to H2O2 powered by renewable energy.