Highly efficient photocatalytic H2O2 generation by α-S/vacancy- modified g-C3N4 heterojunction in a two-phase reaction system

Recently, it was reported photocatalytic H 2 O 2 generation performed in biphasic system could significantly increase the H 2 O 2 yield. Aiming to further improve the H 2 O 2 yield, hydrophobic heterojunction of α-S and vacancy-rich g-C 3 N 4 (CNN) was constructed. H 2 O 2 production performance tests demonstrated the 0.2α-S/CNN composite achieved H 2 O 2 yields 1.72 and 1.99 times higher than pristine CNN and α-S, respectively. N-(C) 3 bonded nitrogen(N 3 C ) promoted oxygen activation, and heterojunction facilitated the separation of photogenerated holes and electrons. These contributed more effective photocatalytic synthesis of H 2 O 2 . The optimal 0.2α-S/CNN achieved a production rate of 2218 μmol g −1 , with an impressive apparent quantum yield (AQE) of 6.92 % under 455 nm monochromatic light, outperforming the state-of-the-art catalysts. The proposed mechanism suggested that photogenerated electrons migrated from α-S to CNN, reducing adsorbed O 2 to form •O 2 − radicals. These radicals subsequently reacted with water in the aqueous phase to generate H 2 O 2 via 2e − ORR. Due to the strong hydrophobicity of the catalyst, most •O 2 − radicals were generated in benzyl alcohol (BA) phase, while H 2 O 2 predominantly formed in the aqueous phase. This spatial separation delayed H 2 O 2 decomposition, facilitating its accumulation and enhancing overall yield.