SnS Nanoparticles Embedded in BiVO Surfaces via Eutectic Decomposition for Enhanced Performance in Photoelectrochemical Water Splitting.

BiVO has garnered substantial interest as a promising photoanode material for photoelectrochemical water-splitting due to its narrow band gap and appropriate band edge positions for water oxidation. Nevertheless, its practical use has been impeded by poor charge transport and sluggish water oxidation kinetics. Here, a hybrid composite photoanode is fabricated by uniformly embedding SnS nanoparticles near the surface of a BiVO thin film, creating a type II heterostructure with strong interactions between the nanoparticles and the film for efficient charge separation. This structure forms via eutectic melting during atomic layer deposition of SnS with subsequent phase separation between SnS and BiVO at room temperature, offering greater advantages and flexibilities over conventional exsolution techniques. Furthermore, the SnS/BiVO hybrid composite is coated with a thin amorphous ZnS passivation layer to accelerate charge transfer process and enhance long-term stability. The optimized BiVO/SnS/ZnS photoanode exhibits a photocurrent density of 5.44 mA cm at 1.23 V versus RHE, which is 2.73 times higher than that of the BiVO photoanode, and a dramatic improvement in photostability retention at 1.23 V versus RHE, increasing from 55% to 91% over 24 hours. This method of anchoring nanoparticles onto host materials proves highly valuable for energy and environmental applications.