Two-Dimensional Metal-Organic Frameworks Simultaneously Achieving High Activity and Selectivity toward H2O2 Production.

The direct electrochemical production of hydrogen peroxide (H2O2) via a two-electron (2e-) oxygen reduction reaction (ORR) is an efficient on-site production method. However, due to the scaling relationship between the adsorption free energy of reaction intermediates, it is difficult for existing catalysts to achieve both catalytic selectivity and activity. Herein, by first-principles calculations, we systematically investigated the stability, catalytic selectivity, and activity toward 2e- ORR in an acidic medium of a class of two-dimensional (2D) metal-organic frameworks (MOFs) M3(C6X3Y3)2 (M = Fe, Co, Ni, Cu, Pd, Ag, Pt, and Au; X = Y = NH, O, S, Se and X, Y = NH, O, S, X ≠ Y). Among the 56 monolayer M3(C6X3Y3)2, three are both active and selective toward 2e- ORR. Noble-metal-free Cu3(C6N3H3S3)2 showed the best H2O2 generation activity with a remarkable limiting potential of 0.65 V (corresponding to the overpotential of 0.05 V). Compared to metal surfaces, the modest binding of OOH* adsorbate on M3(C6X3Y3)2 leads to different scaling relations between the absorption free energy of OOH* and O*, which could simultaneously achieve high activity and selectivity toward H2O2 production. Further analysis through the Pearson correlation coefficients shows that the catalytic selectivity and activity of M3(C6X3Y3)2 lead to band hybridization. This work advances the understanding and application of M3(C6X3Y3)2 and other 2D MOFs for efficient H2O2 production.