Hydrophilic hydrogen-bonded organic frameworks/g-C3N4 all-organic Z-scheme heterojunction for efficient visible-light photocatalytic hydrogen production and dye degradation

Abstract

Herein, a novel all-organic Z-scheme hydrogen-bonded organic frameworks (HOFs)/g-C3N4 nanosheets (CNNS) heterojunction photocatalyst is synthesized through an in-situ electrostatic method. Characterization and density functional theory studies together verify that the band structures with staggered alignment between HOFs and CNNS can induce a rapid Z-scheme interfacial charge-transfer pathway. Combing the complementary advantages of HOFs and CNNS, the fabricated Z-scheme HOFs/CNNS heterojunction inhibits photoinduced electron-hole recombination and more charge carriers are accumulated to produce highly reactive substances (•O2–, •OH and h+). In addition, the superior hydrophilicity of HOFs can enhance the interaction of HOFs/CNNS heterojunction with water molecules and methyl orange pollutant, which is beneficial to boosting photocatalytic activity. Therefore, in contrast to inactive pure HOFs, the novel Z-scheme HOFs/CNNS heterojunction exhibits a high photocatalytic hydrogen evolution rate of 4450 μmol h-1g−1 with an apparent quantum efficiency (AQY) of 22 % at 450 nm, which is approximately 11 times higher than that of pure CNNS. Additionally, such heterojunction enables 100 % degradation of methyl orange within 60 min.