Bifunctional metastable LaOCl@hcp-Ni nanocomposite via Mott-Schottky effect for improved photoelectrocatalytic and photocatalytic activities

Abstract

Fabrication of low-cost, stable and highly efficient catalysts for clean energy and environmental control applications is an urgent task. In this work, we have successfully synthesized a multifunctional two-dimensional rare earth-based LaOCl@hcp-Ni heterostructure via a simple one-pot method. Here, the semiconductor LaOCl nanoparticles were well deposited on the metastable metal hcp-Ni, and the hexagonal close-packed structure of hcp-Ni matched the layered-structure LaOCl to form a highly active LaOCl@hcp-Ni Schottky catalyst. Furthermore, LaOCl@hcp-Ni were tested for Photoelectrochemical (PEC) oxygen evolution reaction (OER) in alkaline media and the photocatalytic (PC) degradation of Rhodamine B (RhB) in aqueous solution. LaOCl@hcp-Ni shows excellent PEC-OER catalytic activity and RhB degradation performance under artificial simulated sunlight. This enhancement of PEC and PC performance is due to the Schottky interface constructed by the coupling of hcp-Ni and LaOCl, which generates an interface electric field to effectively promote the transfer of photogenerated electrons from the semiconductor LaOCl to the metal hcp-Ni through the interface. Thus, energy band gap of LaOCl with oxygen defects is adjusted to the visible light region and their valence state of La is lowered, realizing high-efficiency visible light catalytic activity. Thus, it would be a potential rare earth-based Schottky catalyst, which can be used for the PEC oxygen evolution and the PC degradation of organic pollutants. • We successfully synthesized a bifunctional LaOCl@hcp-Ni nanocomposite as Schottky catalyst for PEC-OER and PC degradation of RhB. • Metal hcp-Ni with a metastable structure has high catalytic performance due to its low symmetry. However, its synthesis is difficult and usually requires high pressure conditions. We successfully synthesized hcp-Ni under mild oleylamine solution conditions at 320 °C. • This enhancement of PEC and PC performance is due to the Schottky interface effect between the semiconducting LaOCl and the metallic hcp-Ni, as well as the synergistic effect of the structural distortion and defects of the LaOCl.