MnO2 and carbon nanotube co-modified C3N4 composite catalyst for enhanced water splitting activity under visible light irradiation

MnO2 and carbon nanotube co-modified C3N4 (CNTs/MnO2-C3N4) ternary composite was synthesized. The prepared catalyst was investigated by X-ray diffraction, transmission electron microscopy, UV-Vis absorption spectroscopy, nitrogen sorption, X-ray spectroscopy, photoluminescence spectroscopy and transient photocurrent responses. The photocatalytic activity of the ternary catalyst was evaluated by hydrogen and oxygen evolution for visible-light-driven water splitting without the addition of sacrificial agents. Compared with MnO2/C3N4 and CNTs/C3N4 catalysts, the CNTs/MnO2-C3N4 ternary catalyst showed an enhanced visible light-induced water splitting activity with a H2 evolution rate of 122 μmol h−1. In the CNTs/MnO2-C3N4 ternary catalyst, CNT can capture the electron from C3N4 and facilitate hydrogen evolution, and MnO2 catalyzes the decomposition of hydrogen peroxide for O2 evolution, leading to the efficient separation of photogenerated electron-hole pairs, thus an enhanced water splitting performance is achieved.