Synthesis of carboxyl-functionalized g-C3N4 supported Cu-MOFs photocatalyst and its efficient photocatalytic hydrogen production

Addressing the low surface area and high charge recombination of graphitic carbon nitride (g-C 3 N 4 ), this study employs a synergistic carboxylation and MOF-loading strategy. Copper-based MOF (Cu-MOF) was uniformly loaded onto carboxylated spherical g-C 3 N 4 (C 3 N 4 –C) via a solvothermal method, creating a visible-light-responsive C 3 N 4 –C-MOF photocatalyst. Material characterization results indicate that the characteristic peak at 1632 cm −1 in the Fourier Transform Infrared Spectroscopy confirms the successful grafting of 4-carboxybenzoic acid (4-CBA). Carboxylation enhanced hydrophilicity and optimized surface charge, improving reactant adsorption. Photoelectrochemical tests showed significantly boosted visible light absorption, increased photocurrent density, and reduced EIS arc radius, confirming efficient interfacial charge separation. Photocatalytic hydrogen production experiments revealed that under simulated solar irradiation, the hydrogen production rate of C 3 N 4 –C-MOF2.0 reached up to 12.68 mmol g −1  h −1 , representing an approximately 1.68-fold increase compared to the unmodified C 3 N 4 -MOF. This work provides a novel approach for designing MOF/functionalized g-C 3 N 4 composites, advancing solar-driven hydrogen production.