CoAl-LDH incorporated g-C3N4 nanosheets: a dual-function photocatalyst for hydrogen production and dye degradation

The construction of heterojunction nanostructures and the engineering of their morphology are regarded as significant strategies for enhancing photocatalytic performance. This study presents the preparation of a novel binary g-C₃N₄/@CoAl-LDH heterostructure photocatalyst, achieved through the hydrothermal synthesis interpret, which involved the loading of well-dispersed g-C₃N₄ nanosheets onto the surface of the CoAl-layered double hydroxide (CoAl-LDH) precursor. The investigation of the samples encompassed an examination of their surface morphology, crystalline structure, and chemical state through the utilisation of scanning electron microscopy (SEM), X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The findings suggest a precisely calibrated band gap energy spanning from pure CoAl-LDH to pure CN. Furthermore, the significant attenuation of the photoluminescence signal and the extended lifetime of photogenerated charges, as evidenced by time-resolved photoluminescence spectra, underscore the exceptional photocatalytic performance of these composites. The as-prepared 15 mol% CoAl-LDH/CN exhibited a remarkable photocatalytic hydrogen evolution rate of 3377 µmol h⁻¹ g⁻¹, which was seven times higher than that of pure CoAl-LDH (477 µmol h⁻¹ g⁻¹). The enhanced activity could be mainly attributed to its unique structure and high surface area. Distinct from ordinary heterojunction photocatalysts, two-dimensional (2D) heterojunctions with abundant 2D coupling interfaces and strong interfacial interaction could efficiently suppress the recombination of photo-induced charge carriers and shorten charge transmission distance demonstrate an enhanced ability to effectively mitigate the recombination of photo-induced charge carriers while also reducing the distance required for charge communication. The sample was further monitored to degrade crystal violet (CV) under visible light. The highest photocatalytic efficiency was recorded for the 15 mol% CoAl-LDH/CN, which achieved 99% degradation efficiency and reaction rate constant (k) of 0.0871 min⁻¹. Radical scavenging experiments showed that^⋅OH, e⁻, and h⁺ played significant roles in the degradation process.