Bulk and surface dual-defects NiOx/B-TiO2@CdS photocatalyst for stable and effective photocatalytic hydrogen evolution

Nonmetallic doping can induce oxygen vacancies on semiconductor surfaces to form local gaps and subsequently regulate semiconductor absorption band edge. However, the existence and instability of these holes challenge the activity and stability of the semiconductor catalysts. In this work, we demonstrate a molten salt homogeneous doping method of non-metallic doping involving double doping, on the surface and bulk phase of the catalyst, thereby NiOx/B-TiO2@CdS core–shell nanowires achieving high photocatalytic hydrogen evolution activity. The double doping function of the homogeneous method is realized by the fact that B2O3 acts as both molten salt and doping precursor. The dual-doping of B reduced exciton binding energies and improves the stability and density of oxide vacancies resulting in high light utilization rate. The results showed that the oxygen vacancy density of the catalyst remained at 83.3% after 10 h of reaction. In addition, the construction of a heterojunction enhances the separation efficiency of photogenerated carriers, and the loading of group catalyst reduces the activation energy of reaction, thus improving the catalytic efficiency of the catalyst. As a result, the photocatalytic performance of the B-TiO2@CdS core–shell structure photocatalyst is significantly better than that of bare CdS. The H2 evolution rate is increased to 8.11 mmol/g with NiOx/B-TiO2@CdS, which is 5.7 times greater than CdS (1.42 mmol/g). The research furnishes a new strategy for the design of stable oxygen vacancies within heterojunction-based photocatalysts to produce H2 from photocatalytic water splitting.