Abstract: Perovskite oxides (ABO₃) are thought to be promising electrocatalysts for oxygen evolution reaction (OER), but their specific surface area (SSA) is too low (usually < 10 m² g^-1). Developing advanced ABO₃ electrocatalysts with high SSA and optimized structure is of great significance but remains a tremendous challenge. Herein, we propose a general strategy for fabrication of mesoporous perovskite oxide nanosheets (MPONs) with controllable atomic doping via self-sacrificial template-induced nanostructure modulation. A variety of MPONs including LaFeO₃, A-site-doped LaFeO₃ (A-LaFeO₃, where A is Pr, Nd, Sm, Eu, or Gd) and B-site-doped LaFeO₃ (B-LaFeO₃, where B is Mn, Co, Ni, Cu, or Zn) have been achieved. Interestingly, it is discovered that the catalytic activities of A-LaFeO₃ MPONs as OER catalysts are overall higher than those of B-LaFeO₃ ones. Especially, the screened Eu-LaFeO₃ MPONs only require a low overpotential of 267 mV at 10 mA cm^-2, outperforming most reported perovskite oxides. The superior catalytic activity of Eu-LaFeO₃ MPONs is attributed to their favorable porous structure, which increases the density of active sites, and enhanced lattice oxygen participation, which improves the intrinsic activity. This study provides guidance for the design and controlled synthesis of advanced rare-earth-doped MPONs with ultrahigh SSA for enhanced electrocatalysis.

Key words: Mesoporous, Perovskite oxides, Rare-earth doping, Oxygen evolution reaction, Electrocatalysts