Synergistic effect of nitrogen-doping and graphene quantum dot coupling for high-efficiency hydrogen production based on titanate nanotubes

Abstract Highly efficient H 2 production from water splitting has been achieved by N-doped titanate nanotubes (N-TNTs) decorated with graphene quantum dots (GQDs) in this work. In order to promote charge carrier transmission at the interface, a facile and environmentally friendly in situ growth method was employed to construct a strongly coupled N-TNT/GQD composite photocatalyst. The results revealed that N atoms were effectively doped into the crystal lattice of the TNTs in the form of both interstitial N and substitutional N, and the GQDs were decorated onto both the inner and outer surfaces of the N-TNTs through the formation of Ti–O–C chemical bonds. Photoelectrochemical measurements proved that, in N-TNT/GQD composite, N-doping can extend light response to the visible-light range, and the coupling with GQDs not only enhanced visible-light absorption, but also promoted interfacial charge carrier transfer. Due to the synergistic effect between N-doping and GQD coupling, the closely integrated N-TNT/GQD composite exhibits a much superior photocatalytic H 2 production performance under UV–vis irradiation, being 2.1 times higher than that of pure TNTs.