In situ construction of donor–acceptor structured g-C3N4 nanotubes incorporated with pyridine heterocyclic rings for efficient photocatalytic water splitting

Abstract

Polymeric carbon nitride (PCN) materials, as an emerging class of metal-free photocatalysts, have demonstrated significant potential in the field of solar energy conversion, particularly in areas of water splitting. But the utilization of PCN is restricted by its high carrier recombination rate and low charge transfer efficiency. In order to address these challenges, this work involves choosing pyridyl organic small molecules of nicotinic acid (NA) and melamine to construct donor–acceptor (D–A)-structured carbon nitride nanotubes. Pyridine heterocyclic rings are converged at the edge of the PCN structure via supramolecular self-assembly, facilitating the fabrication of donor–acceptor-structured carbon nitride nanotubes. The pyridine heterocyclic rings, with their strong electronic ability, create a preferred pathway for electronic transfer. This effectively mitigates carrier recombination within the molecular plane. In addition, the unique hollow tubular structure of carbon nitride nanotubes enhances their visible light absorption ability, expands the surface area of the catalyst, and then increases the number of catalytically active sites, which consequently enhances photocatalytic performance. The H₂ production rates of one-dimensional tubular carbon nitride doped with 100 mg of NA (designated as NA₁₀₀-CN) is 2584.2 μmol g⁻¹ h⁻¹, which is 4.7 times that of pristine PCN. This investigation elucidates the mechanism of charge transfer from D to A, describing the response mechanism of photocatalysis, with profound implications for advancing clean energy, environmental preservation and sustainable development.