Phosphorus-Doped Carbon Nitride Tubes with a Layered Micro-nanostructure for Enhanced Visible-Light Photocatalytic Hydrogen Evolution

Abstract

Phosphorus-doped hexagonal tubular carbon nitride (P-TCN) with the layered stacking structure was obtained from a hexagonal rod-like single crystal supramolecular precursor (monoclinic, C2/m). The production process of P-TCN involves two steps: 1) the precursor was prepared by self-assembly of melamine with cyanuric acid from in situ hydrolysis of melamine under phosphorous acid-assisted hydrothermal conditions; 2) the pyrolysis was initiated at the center of precursor under heating, thus giving the hexagonal P-TCN. The tubular structure favors the enhancement of light scattering and active sites. Meanwhile, the introduction of phosphorus leads to a narrow band gap and increased electric conductivity. Thus, the P-TCN exhibited a high hydrogen evolution rate of 67 μmol h-1 (0.1 g catalyst, λ >420 nm) in the presence of sacrificial agents, and an apparent quantum efficiency of 5.68 % at 420 nm, which is better than most of bulk g-C3N4 reported. Phosphorus-doped hexagonal carbon nitride tubes were obtained from a rod-like supramolecular precursor through phosphorous acid assisted hydrothermal and subsequent thermal treatment. It exhibits a high visible-light photocatalytic hydrogen evolution performance that is better than most reported bulk carbon nitrides, which is due to the hierarchical micro-nanostructure and P doping.