Facile synthesis of bimodal macroporous g-CN/SnO nanohybrids with enhanced photocatalytic activity.

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 CN (g-CN), as an analogy to two-dimensional (2D) graphene, is highly identified as a visible-light-responsive polymeric semiconductor. Moreover, the feasibility of g-CN in making porous structures has been well established. However, the preparation of macroporous g-CN with abundant porous networks and exposure surface, still constitutes a difficulty. To solve it, we report a first facile preparation of bimodal macroporous g-CN hybrids with abundant in-plane holes, which is simply enabled by in-situ modification through thermally treating the mixture of thiourea and SnCl (pore modifier) after rotary evaporation. For one hand, the formed in-plane macropores endow the g-CN 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-CN and SnO consolidate the electron transfer reaction to greatly reduce the recombination probability. As a consequence, the resulted macroporous g-CN/SnO nanohybrid had a high specific surface area (SSA) of 44.3 m/g that was quite comparable to most nano/mesoporous g-CN 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-CN/SnO hybrid exhibited about 2.4-fold increment in the photoactivity compared with pure g-CN. Additionally, the recyclability of such hybrid could be guaranteed after eight successive uses.