In-situ La doped Co3O4 as highly efficient photocatalyst for solar hydrogen generation

Photocatalytic hydrogen production via water splitting using metal oxide semiconductors has attract great interests because of the two electrons on the kinetics. Pristine Co₃O₄ was widely studied as efficient photocatalyst, but prefers to produce oxygen due to its lower band-edge positions with regard to water redox potentials. In this work, high efficient photocatalyst basing on non-noble La doped Co₃O₄ on graphene, i.e., La_xCo_3-xO₄/G, were first reported and prepared by the microwave hydrothermal synthesis. In this newly developed hybrids, La and Co ions were adsorbed on the surface of graphene (G) and subsequently reacted with ammonia to yield the La_xCo_3-xO₄/G nanohybrid by in-situ chemical deposition methods. The activity for hydrogen generation of the nanohybrid exhibits 2 times higher than undoped Co₃O₄/G under visible light irradiation. The H₂ evolution of nanohybrid reaches 6.543 mmol g^?1 h^?1 when the molar ratio of La/Co is 10% in the nanohybrid. Our experimental results indicate the incorporation of La doped in the Co₃O₄ crystal lattice not only forms the lattice defects, resulting in provision for capture trap and the separation of electrons and holes, but also changes the band structure to eventually improve the photocatalytic activity under visible light. Therefore, non-noble La is a promising substitute to prepare highly efficient hydrogen photocatalyst and can be extendedly applied to the other metal oxide semiconductors for solar hydrogen production.