Three-dimensional P-doped porous g-C3N4 nanosheets as an efficient metal-free photocatalyst for visible-light photocatalytic degradation of Rhodamine B model pollutant

As a typical metal-free photocatalyst, graphitic carbon nitride (g-C3N4) has attracted great attention for photocatalytic degradation of various organic pollutants. In this study, three-dimensional (3-D) phosphorus (P)-doped porous g-C3N4 nanosheets were prepared successfully via the thermal oxidation and element doping associated method. Abundant in-plane mesopores (from 2 nm to 50 nm), high specific surface area (202.9 cm2 g−1) and desirable P content (0.87%) were obtained for this 3-D P-doped porous g-C3N4 nanosheets. Taking Rhodamine B as a model pollutant, the photocatalytic properties of this 3-D P-doped porous g-C3N4 nanosheets photocatalyst were investigated, and the mechanism of photocatalytic degradation was also proposed. The 3-D P-doped porous g-C3N4 nanosheets showed the much enhanced visible-light photocatalytic activity, with Rhodamine B degradation ratio of 99.5% and a kinetic reaction rate constant of 0.120 min−1, compared to porous g-C3N4 nanosheets (58.2% and 0.031 min−1). The catalytic mechanism analysis shows that the active radicals of •OH and •O2− have strong oxidizing property, which can quickly decompose target organic dyes. The mesoporous structure and high P content of doping endowed photocatalyst with abundant active sites, high conductivity, and efficient separation of photoproduced electron-hole pairs.