Synthesis of hollow donut-like carbon nitride for the visible light-driven highly efficient photocatalytic production of hydrogen and degradation of pollutants

Abstract

Hollow donut-like g-C₃N₄ (CMU-500) was prepared by controlling the calcination temperature of a supramolecular polymer composed of cyanuric acid, melamine and urea at 500 aC in air. CMU-500 possessed a large specific surface area of 92 m² g⁻¹, which is ten-fold higher than that of bulk g-C₃N₄. It exhibited high separation efficiency for photogenerated electron–hole pairs and high conductivity for interfacial charge transfer. CMU-500 exhibited high visible light photocatalytic activity for the degradation of rhodamine B (k = 0.364 min⁻¹) and reduction of Cr(VI) (k = 0.463 min⁻¹), in which the rate constant, k, was more than 30 times that of bulk g-C₃N₄. The hydrogen production efficiency of CMU-500 with Pt as a co-catalyst was as high as 2260 μmol g⁻¹ h⁻¹ under visible light irradiation, which is 180 times higher than that of bulk g-C₃N₄. Highly stable photocatalytic activity was observed in both photocatalytic degradation and hydrogen production through four cycles of tests. Thus, our results suggest a new strategy to design and synthesize highly effective photocatalysts towards the treatment of environmental pollution and hydrogen production.