Metal-free hybrid composite particles with phosphorus and oxygen-doped graphitic carbon nitride dispersed on kaolin for catalytic activity toward efficient hydrogen release

Abstract

Here, hybrid kaolin-g-C3N4 heterostructure particles were fabricated by calcination in the first step, followed by hydrothermal phosphoric acid activation in the second step, and phosphorus (P) and oxygen (O) doped kaolin-g-C3N4 metal-free catalyst was synthesized. This hybrid metal-free catalyst was used for the first time for the production of effective hydrogen (H2) from sodium borohydride (NaBH4) methanolysis. The hydrogen generation rate (HGR) value of 5500 ml min−1g−1 was obtained with the P and O doped kaolin-g-C3N4 catalyst. The activation energy (Ea) of 31.90 kJ mol−1 by P and O doped kaolin-g-C3N4 for the production of H2 was obtained. The kaolin-g-C3N4 and P and O doped kaolin-g-C3N4 metal-free catalysts were systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Based on the results obtained, the mechanism of P and O-doped kaolin-g-C3N4 catalyst on H2 production from NaBH4 methanolysis was also proposed.