In Situ Construction of Ag/TiO₂/g-C₃N₄ Heterojunction Nanocomposite Based on Hierarchical Co-Assembly with Sustainable Hydrogen Evolution

The construction of heterojunctions provides a promising strategy to improve photocatalytic hydrogen evolution. However, how to fabricate a nanoscale TiO₂/g-C₃N₄ heterostructure and hinder the aggregation of bulk g-C₃N₄ using simple methods remains a challenge. In this work, we use a simple in situ construction method to design a heterojunction model based on molecular self-assembly, which uses a small molecule matrix for self-integration, including coordination donors (AgNO₃), inorganic titanium source (Ti(SO₄)₂) and g-C₃N₄ precursor (melamine). The self-assembled porous g-C₃N₄ nanotube can hamper carrier aggregation and it provides numerous catalytic active sites, mainly via the coordination of Ag⁺ ions. Meanwhile, the TiO₂ NPs are easily mineralized on the nanotube template in dispersive distribution to form a heterostructure via an N-Ti bond of protonation, which contributes to shortening the interfacial carrier transport, resulting in enhanced electron-hole pairs separation. Originating from all of the above synergistic effects, the obtained Ag/TiO₂/g-C₃N₄ heterogenous photocatalysts exhibit an enhanced H₂ evolution rate with excellent sustainability 20.6-fold-over pure g-C₃N₄. Our report provides a feasible and simple strategy to fabricate a nanoscale heterojunction incorporating g-C₃N₄, and has great potential in environmental protection and water splitting.