Visible-light-driven photocatalyst based upon metal-free covalent triazine-based frameworks for enhanced hydrogen production

Abstract

Photocatalytic H₂ production via water splitting has emerged as an eco-friendly and green technology to efficiently utilize solar energy. Developing visible light active photocatalysts, especially the metal-free ones, is crucial to access this technology considering their economic and environmental benefits. Hence, a facile UV reduction method was adopted to fabricate a highly active metal-free photocatalyst by modifying covalent triazine-based frameworks (CTFs) with reduced graphene oxide (rGO). The optimized CTF composite with 2 wt% rGO exhibited a 4.3-fold activity enhancement compared with pristine CTFs, showing a prime H₂ evolution efficiency of 894 μmol g⁻¹ h⁻¹. The contributions of rGO to the photocatalytic system and the interaction between rGO and CTFs were thoroughly studied. The modification of rGO endowed the photocatalyst with improved visible-light absorption, stronger reductive ability, and faster separation rate of photoinduced carriers. Moreover, the covalent C–O–C bond formed in the two components facilitates the directional transfer of photoinduced electrons. A low-cost and robust photocatalyst for clean energy production is constructed in this work, providing inspirations for the design and fabrication of metal-free photocatalytic materials with superior performance.