Synergistic Na-K dual active sites on ultrathin g-C3N5 nanosheets boost electron delocalization for natural-oxygen-condition H2O2 photosynthesis

Ultrathin g-C 3 N 5 with Na-K sites, N-vacancies, and –C N was synthesized. • CN-Na-K yields 4739.89 μmol‧g −1 ‧h −1 H 2 O 2 under aeration-free conditions. • –C N and N-vacancies synergistically boost π-electron delocalization. • Na-K dual sites drive both ORR and WOR pathways for H 2 O 2 production. Photocatalytic solar-driven H 2 O 2 synthesis offers a sustainable energy route but is often limited by the need for supplemental oxygen. To overcome barriers, a distinctive ultra-thin g-C 3 N 5 nanosheet with cyano groups (–C N), N-vacancies, and Na-K dual active sites (CN-Na-K) was structured for H 2 O 2 production in natural-oxygen-conditions (aeration-free). The introduction of the –C N function as an electron pump to construct an internal electric field (IEF) promoted charge separation. Simultaneously, N-vacancies broke the structural localization to enhance π-electron delocalization, creating high-speed channels for carrier transport. Crucially, the Na-K dual sites acted as catalytic centers that enabled the water oxidation reaction (WOR) by driving the formation of key intermediates (*O 2 , *OOH, and *OH), where Na + acted as a powerful electron sink, and K + promoted excited-state electrons and stabilized holes. Therefore, the –C N, N-vacancies, and Na-K dual active sites synergistically promoted an enhanced H 2 O 2 production rate of CN-Na-K (1260.03 μmol‧g −1 ‧h −1 in LED lamp and 4739.89 μmol‧g −1 ‧h −1 in Xe lamp) under aeration-free conditions. Besides, characterizations and density functional theory (DFT) calculations confirmed the CN-Na-K system produced H 2 O 2 via a dual-channel pathway for the oxygen reduction (ORR) and WOR. This work provides a systemic design for electronic delocalization and dual active site engineering to achieve efficient aeration-free H 2 O 2 production. Download: Download high-res image (262KB) Download: Download full-size image