ZIF-67 templated Co2+, cyanate-doping to construct S-schemed carbon nitride junction for boosting photocatalytic H2 evolution

Abstract

Herein a novel carbon nitride (CN) homojunction between Co2+, cyanate group spatially co-doped and undoped domain is first designed via the ZIF-67 self-templated doping and polymeric condensation of CN, for efficient photocatalytic H2 evolution (PHE). The microstructure characterizations on the ZIF-67 amount-dependent crystallinity and modifications confirm the successful construction of CN homojunction between Co2+-concentrated domain and undoped domain (CoCN). As a result, the optimized CoCN shows an improved PHE rate (2512 μmol·g−1·h−1) 2.93 times that of pristine CN, with further 1.7 times increase after 5 rounds of cycling (4305 μmol·g−1·h−1). Steady-transient photoluminescence and photo-electrochemical investigations demonstrate that ZIF-67 self-templated doping enhances visible light absorption and the separation/transfer of photogenerated carriers. Further energy-band analysis suggests that the coupling of the doped and undoped domains facilitates the built-in electric field and band bending, leading to Self-S-Scheme mechanism of photocatalysis. This work provides a new method for the design of CN-based junctions via ZIF-67 templated doping boosting photocatalytic activity.