Single‐Atom Catalysts with p‐Block Metals Surpass Transition‐Metal Counterparts in the Photocatalytic H2O2 Production

Abstract Growing interest in p‐block metal single‐atom catalysts (PM‐SACs) is driven by their low toxicity, economic viability, and transition metal‐like catalytic properties. However, selection criteria for p‐block single‐atom species and catalytic mechanisms of PM‐SACs remain unclear. This study explores the catalytic abilities of PM‐SACs and their transition metal counterparts (TM‐SACs) based on polymetric carbon nitride (PCN) for photocatalytic hydrogen peroxide (H 2 O 2 ) production. Using thermodynamic barriers as a key descriptor, it was found that PM‐SACs can surpass TM‐SACs in H 2 O 2 production due to a lower energy barrier for *OOH intermediate formation resulting from optimized p‐p hybridization. Specifically, Sb‐SAC based on PCN shows the highest apparent quantum yield of 35.3 % at 400 nm. This study offers a rationale for the utilization of p‐block SACs in the context of sustainable chemical synthesis.