Doping Stabilizing Isolated Active Sites in Perovskite Lattice for Stable H2O2 Electroproduction.

Developing the efficient catalysts with both high 2e- selectivity and stability remains challenging for on-site hydrogen peroxide (H2O2) synthesis. Perovskite oxides possess dense isolated active sites to convert O2 into H2O2, yet their intrinsic structural instability is also equally noteworthy. In this work, one kind of silver-based perovskites, AgNbO3, and the structure stabilization approach are proposed for H2O2 electrosynthesis. The Ag exsolution from the perovskite phase, which triggers the metallic Ag assemblies on surface, is identified as a key origin of electrochemical destabilization for the 2e- ORR process. Simultaneously, the Zr-doping-induced stabilization approach is put forward. The introduction of high-oxyphilic Zr4+ leads charge delocalization of oxygen in the [NbO6] octahedra toward Ag-site region, thereby enhancing Ag-O covalency as evidenced by the increased integrated crystal orbital Hamilton population values and the suppressed exsolution thermodynamics, while the sharply declined phase-transition constant reconfirms that the Zr incorporation retards the Ag-migration kinetics in terms of experimentation. The resulting Zr-doped AgNbO3 shows outstanding structural stability maintaining the above 90% Faradaic efficiency even at high-current and long-term operation. This work unveils the origination of perovskite destabilization during the 2e- ORR process, and offers a general strategy for stabilizing isolated active sites in electrochemical application.