Single-atomic p-block metal sites in 2D conjugated coordination polymers endow near-100 % selectivity for H₂O₂...

High selectivity and catalytic activity in the electrochemical two-electron oxygen reduction reaction to produce hydrogen peroxide (H₂O₂) remain challenging. Herein, a series of two-dimensional p-block metal-based conjugated coordination polymers with optimal *OOH binding energies are developed. The H₂O₂ selectivity reaches nearly 100 % in the potential range of 0.40-0.60 V versus reversible hydrogen electrode (vs. RHE) on Sn-1,2,4,5-benzenetetramine catalysts. The onset potential is 0.745 V vs. RHE (at 0.1 mA cm^-2). In 0.1 M KOH, an impressive stability is achieved in the flow cell, maintaining 200 mA cm^-2 for over 20 h with a H₂O₂ yield rate of 14.7 mol g^-1 h^-1. Systematic characterizations and density functional theory calculations indicate that the conjugated structure not only accelerates the reaction kinetic but also appropriately modulates the electronic structure of p-block metal sites. This work provides insights into single-atomic p-block metal sites for practical application in H₂O₂ electrosynthesis.