Metal organic framework derived heteroatoms and cyano (-C≡N) group co-decorated porous g-C3N4 nanosheets for improved photocatalytic H2 evolution and uranium (VI) reduction

The introduction of heteroatoms and functional groups in g-C3N4 generally has great advantages in enhancing the photocatalytic performance. In this work, the heteroatoms (Zn + C) and cyano (-C=N) group co-decorated porous g-C3N4 nanosheets (DCNNS) photocatalysts were successfully synthesized through direct calcination of the mixed urea and metal-organic frameworks. The optimized DCNNS displayed a maximum H-2 evolution rate of similar to 484.09 mu mol/h with a quantum efficiency of similar to 3.43% at 420 nm, and the photocatalytic U(VI) reduction activity was improved by similar to 6.09 times. The enhanced photocatalytic performance could be ascribed to following benefits: (1) the modified DCNNS shared the two-dimensional layered structure of g-C3N4, and the massive nanopores in the nanosheets provided more reaction sites and diffusion channels for accelerated mass transfer; (2) the formation of cyano group greatly broadened the light response range and also acted as strong electron-withdrawing group for improving the carrier separation rate; (3) heteroatoms doping modulated the band gap, increased the electric conductivity, promoted the carrier separation and transport, and prolonged the electron lifetime to enhance photocatalytic performance. This work suggested that the heteroatoms and functional groups co-decoration could significantly improve the performance of g-C3N4-based photocatalysts and hold great potential to be further explored for energy and environmental applications. (C) 2020 Elsevier Inc. All rights reserved.