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

Abstract

polymeric carbon nitrides (PCN), as an emerging class of metal-free photocatalysts, have demonstrated significant potential in the field of solar energy conversion, particularly in the areas of water splitting. But the utilization of it is restricted by high carrier recombination rate and low charge transfer efficiency. In order to address these challenges, this work chooses pyridyl organic small molecules nicotinic acid 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 g-C3N4 nanotubes. Strong electronic ability of the pyridine heterocyclic rings establishes a preferential electronic transfer pathway within the D-A composite material, effectively mitigating carrier recombination within the plane. In addition, the unique hollow tubular structure of carbon nitride nanotubes enhances the visible light absorption ability, expands the surface area of the catalyst, and then increases the catalytically active sites, consequently enhancing photocatalytic performance. The photocatalytic activity of one-dimensional tubular carbon nitride doped with 100 mg nicotinic acid (designated as NA100-CN) is 2584.2 µmol g-1 h-1, which is 4.7 times that of the single 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.