Facile synthesis of bimodal macroporous g-C3N4/SnO2 nanohybrids with enhanced photocatalytic activity

Abstract

It is of vital importance to construct highly interconnected, macroporous photocatalyst to improve its efficiency and applicability in solar energy conversion and environment remediation. Graphitic-like C3N4 (g-C3N4), as an analogy to two-dimensional (2D) graphene, is highly identified as a visible-light-responsive polymeric semiconductor. Moreover, the feasibility of g-C3N4 in making porous structures has been well established. However, the preparation of macroporous g-C3N4 with abundant porous networks and exposure surface, still constitutes a difficulty. To solve it, we report a first facile preparation of bimodal macroporous g-C3N4 hybrids with abundant in-plane holes, which is simply enabled by in-situ modification through thermally treating the mixture of thiourea and SnCl4 (pore modifier) after rotary evaporation. For one hand, the formed in-plane macropores endow the g-C3N4 system with plentiful active sites and short, cross-plane diffusion channels that can greatly speed up mass transport and transfer. For another, the heterojunctions founded between g-C3N4 and SnO2 consolidate the electron transfer reaction to greatly reduce the recombination probability. As a consequence, the resulted macroporous g-C3N4/SnO2 nanohybrid had a high specific surface area (SSA) of 44.3 m2/g that was quite comparable to most nano/mesoporous g-C3N4 reported. The interconnected porous network also rendered a highly intensified light absorption by strengthening the light penetration. Together with the improved mass transport and electron transfer, the macroporous g-C3N4/SnO2 hybrid exhibited about 2.4-fold increment in the photoactivity compared with pure g-C3N4. Additionally, the recyclability of such hybrid could be guaranteed after eight successive uses.