NiS Protective Layer for Repelling Chloride Ion Effectively for Water Oxidation on Photocatalytic Seawater Splitting

Due to the increase of global power use, the shortage of energy supply and global warming have become the main obstacles to social and economic development. Today's society is gradually developing cleaner and greener energy represented by solar energy to alleviate the current energy shortage. Among them, semiconductor photocatalytic water splitting technology is one of the most important methods. However, global freshwater resources are in short supply; the design and synthesis of proper photocatalysts for seawater splitting has been regarded as one of the most powerful approaches solving the dilemma of a shortage of freshwater resources and utilization of solar energy. Based on that, the quaternion Pt/Co3O4–NiS/STO composites for photocatalytic water splitting in a seawater system were successfully synthesized by a simple hydrothermal method and photodeposition method. Noticeably, the loading of Pt and Co3O4 cocatalysts greatly improved the separation efficiency of photogenerated electrons and holes. At the same time, the surface modification of NiS made the photocatalysts able to resist the toxicity of a large number of chloride ions in seawater. The oxygen yield for seawater splitting was nearly twice that of untreated samples and about half of the amount of that in pure water. Our work introduced an ideal modification material structure to demonstrate the feasibility of seawater splitting, which would guide other photocatalytic seawater splitting systems in the future.