2D Ca/Nb-based perovskite oxide with Ta doping as highly efficient H2O2 synthesis catalyst

Perovskite oxides (POs) are emerging as a class of highly efficient catalysts for reducing oxygen to H2O. Although a rich variety of POs-based catalysts have been developed by tuning the complex composition, a highly efficient PO catalyst that is able to alter the reaction pathway from a 4e− process to a 2e− process for H2O2 production has rarely been achieved. We modified the structure and composition of a Ca- and Nb-based PO material by realizing a uniform two-dimensional (2D) morphology and varied Ta doping, resulting in the 2D $${\rm{C}}{{\rm{a}}_2}{\rm{N}}{{\rm{b}}_{3 - x}}{\rm{T}}{{\rm{a}}_x}{{\rm{O}}_{10}}^ - $$ (x = 0, 0.5, 1, and 1.5) monolayer catalysts. The obtained catalysts exhibit a dominant 2e− pathway and show exceptional H2O2 production efficiency. The typical $${\rm{C}}{{\rm{a}}_2}{\rm{N}}{{\rm{b}}_{2.5}}{\rm{T}}{{\rm{a}}_{0.5}}{{\rm{O}}_{10}}^ - $$ nanoflakes showed an onset potential of 0.735 V vs. reversible hydrogen electrode (RHE), a remarkably high selectivity over 95% across a wide range of 0.3–0.7 V, an impressively high Faradaic efficiency of 94%, and a notable H2O2 productivity of 1571 $${\rm{mmol}} \cdot {{\rm{g}}_{{\rm{cat}}}}^{ - 1} \cdot {{\rm{h}}^{ - 1}}$$ . These findings highlight the great potential of 2D perovskite oxide nanoflakes as advanced electrocatalysts for 2e− oxygen reduction reaction.