Retaining the self-released chalcogenate at reconstructed cobalt sites by self-transformed carbonate regulation for boosted oxygen evolution

The in-situ generated oxyanions at electrochemically reconstructed catalysts from metal-based non-oxide compounds have been proven to significantly accelerate oxygen evolution reaction (OER) kinetics. However, it remains a challenge to retain these self-released oxyanions at reconstructed catalysts, hindering its utilization as a tool to develop efficient OER catalysts. Here, we demonstrate a versatile self-transformed carbonate regulation strategy to efficiently retain the self-released chalcogenate at Co oxyhydroxides reconstructed from carbon-incorporated Co selenides under OER conditions. These self-transformed CO32− can induce electron accumulation and narrow d bond at Co sites to facilitate the Co 3d–O 2p orbital hybridization between Co sites and SeOx2− for enhanced SeOx2− retention, which can accelerate the rate-limiting step for *OOH formation during OER. Relative to CoOOH-SeOx2− with limited SeOx2− residues, CoOOH-CO32−/SeOx2− with elevated SeOx2− retention by CO32− regulation exhibited a 5.6-fold increase in current density and a remarkable lower Tafel slope towards OER. This strategy paves a rational avenue to design efficient catalysts for electrooxidation reactions through finely regulating self-released oxyanions at reconstructed structures.