Photo-catalytic H2 evolution over Au modified mesoporous g-C3N4

Abstract

Thermodynamically possible photocatalytic hydrogen production by a prototypical g-C3N4 polymer is characteristically limited due to lack of surface redox sites. In view of optimization, herein we have prepared Au-loaded mesoporous g-C3N4 nanocomposites. As an extansion of the previous work, we explore an in situ method to prepare mesoporous g-C3N4 to favour anchoring of Au NPs over organic–inorganic hybrid silica with reducible functional groups. The characterization results showed homogeneous distribution of Au NPs with average diameter around 4–5 nm on the surface of g-C3N4/MCM-41 nanosheets. The synthesised photocatalysts were characterized by XRD, SEM, TEM, UV–Vis DRS, PL, and FTIR analysis. The photo catalytic activity was investigated by performing water reduction reaction for H2 evolution under visible light irradiation. Au-loaded mesoporous g-C3N4 showed 844 µmol of H2 evolution in 3 h. This enhanced photo catalytic performance was mainly attributed to successful distribution of AuNPs on the surfaces of mesoporous g-C3N4, increasing the extent and effectiveness of electronic communication between gold and the g-C3N4 interface Moreover, mesoporous silica (MCM-41) materials with high textural properties like high surface area, wide pore volume and narrow pore diameter act as an excellent support to load Au NPs with high homogeneity and good dispersion, which can be used for many catalytic applications. Strong covalent character with high textural properties of MCM-41 also helps to stabilize the noble metal NPs and increases the properties like adsorption. The improved optical absorption for the sustainable utilization of solar radiation provides a feasible chemical pathway for constructing g-C3N4 based polymeric systems for application in photocatalysis.