Potassium/cyano group co-incorporation promotes 2e− ORR selectivity in porous ultrathin carbon nitride for photocatalytic H2O2 production

Abstract

Photocatalysis is a promising strategy for the production of H₂O₂, but the promotion of 2e⁻ ORR selectivity remains a challenging goal in this field. Herein, Potassium (K⁺), cyano groups (-C≡N) and porous ultrathin structures were introduced into g-C₃N₄ simultaneously by the hyphenated technique of gas template method and molten salt-assisted method. The K⁺ and –C≡N can broaden the light absorption range, improve the reduction ability and promote electron transfer of the catalyst. Additionally, the presence of a permeable ultrathin structure plays a crucial role in improving the specificity of the 2e⁻ oxygen reduction reaction (ORR). Benefiting from the multiple advantages, the H₂O₂ yield of K⁺ intercalated cyano-rich porous ultrathin g-C₃N₄ (KUCN) reached 781.39 μM with an extraordinary 2e⁻ ORR selectivity of 94.5% (0.30 V vs. RHE). Overall, this study presents a practical approach for designing catalysts based on g-C₃N₄ that exhibit a high selectivity for the 2e⁻ ORR reaction.