Defect engineering induced high metal loading Co-single-atom catalyst on carbon dots for efficient H2O2 electrosynthesis

Co-single atom catalysts (Co-SACs) exhibit high selectivity and efficiency for H₂O₂ electrosynthesis via the two-electron oxygen reduction reaction (2e⁻ORR), with the catalytic activity as significantly influenced by the loading content of Co atoms. However, the loading of Co atoms is typically confined to a low level (<1.0 wt%), which restricts their overall catalytic performance. Herein, we proposed a defect engineering strategy that utilized the carbon dots (CDs) as a platform to capture Co atoms, and constructed a series of Co-SACs with high Co atoms loading (with a maximum of 6.16 wt%), representing a substantial improvement compared to existing benchmarks in the literature. Experimental and characterization results revealed that the defect sites on CDs allowed adequate spacing between the Co atoms, effectively preventing their aggregation and promoting the generation of highly loaded metal atoms. It is worth noting that ECDs-CoSA demonstrated remarkable efficacy and catalytic activity with 93.70 % H₂O₂ selectivity and an impressive H₂O₂ yield of 9.71 mol L⁻¹ h⁻¹ g_cat.⁻¹ in neutral condition. This study presents an effective route for the controlled prepared of Co-SACs with high metal loading, aiming at sustainable and the efficient H₂O₂ electrosynthesis.