CaH2-assisted structural engineering of porous defective graphitic carbon nitride (g-C3N4) for enhanced photocatalytic hydrogen evolution

The practical applications of graphitic carbon nitride (g-C3N4) for photocatalytic hydrogen evolution is strictly hindered by the low surface area, poor light harvesting capability and detrimental recombination of photoexcited charge carriers. Herein, using melamine as precursor and metal hydride (i.e., CaH2) as active agent, we facilely incorporate various types of defects (i.e., nitrogen (N) vacancies (V-N), cyano groups (C (math)N) and surface absorbed oxygen species(O-abs)) into g-C3N4 within a single step. The as-prepared material (denoted as MM-H) exhibits narrowed bandgap, promoted photoexcited electron-hole separation rate and facilitated charge transfer kinetics with enlarged BET surface area and massive porosity. As a result, a prominently enhanced photocatalytic H-2 productivity efficiency (1305.9 mu mol h(-1) g(-1)) is shown on MM-H. This performance is better than that of g-C3N4 with CaH2 post-treatment (617.3 mu mol h(-1) g(-1)) and raw bulk-C3N4 (178.2 mu mol h(-1) g(-1)). This work opens up a new dimension for designing high performance g-C 3 N 4 -based catalysts targeting various photocatalytic processes. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.