Black ZrO2 synthesized by molten lithium reduction strategy for photocatalytic hydrogen generation

To promote the performance of metal oxides, introducing oxygen vacancies is an effective strategy. Oxygen vacancies can tailor the atomic arrangement and band structure, thus optimizing the physical and chemical properties of metal oxides. Herein, we prepared oxygen-deficient black ZrO2 nanoparticles via molten lithium (Li) reduction. Massive oxygen vacancies were introduced into ZrO2 nanoparticles as well as defective disorder domains formed in ZrO2 lattice during the molten lithium treatment process. Benefitting from the defective structure, black ZrO2 with enhanced light absorption demonstrated increased photocatalytic hydrogen generation rate, which was 5 times higher than that of pristine ZrO2. Moreover, molten lithium reduction provides a powerful way to not only implant oxygen vacancies to metal oxides but also extend their applications.