Ultrastable and high-performance seawater-based photoelectrolysis system for solar hydrogen generation

Solar hydrogen production from seawater, the most natural resource on the earth, is an economically appealing for renewable energy conversion. A photoelectrochemical (PEC) seawater-splitting system is greatly challenging for designing stable photoelectrodes and obtaining high and stable photocurrents, strongly preventing corrosion of semiconductors in seawater. In this context, we for the first time report an ultra-stable seawater splitting PEC cell based on the BiVO4 protected by a MoO3 barrier layer. The combination of MoO(3)and Mo/B co-doping on BiVO4 photoanode presents a resembled photocurrent density value of 4.30 mA cm(-2) at 1.23 VRHE in simulated seawater and natural seawater under 1 sun AM 1.5G illumination. Equally importantly, the resulting photoanode is quite stable during natural seawater splitting, which shows strong photocorrosion resistance over 70 h of continuous irradiation. Further theoretical calculations provide an insight into the roles of surface dopants for the reduction of substantial surface charge recombination and improving the photocorrosion resistance during long-term operation in the marine environment. This work provides a new avenue for the robust and stable PEC semiconductors design for hydrogen production by seawater photoelectrolysis. Broader context: Seawater photoelectrolysis is one of the promising alternatives for hydrogen production since sun and seawater represent the two most abundant and available resources reserved on earth. However, the corrosion resistance on photoelectrodes should be paid more attention to long-term operation, where the chloride ions from seawater corrode the electrodes. The highly robust and efficient photoelectrodes are thereby required as one of the critical points on potential application. The BiVO4 photoelectrode is a promising semiconductor for photoelectrochemical (PEC) seawater splitting with a suitable bandgap and favorable conduction band edge position. Unfortunately, this photoelectrode undergoes a poor charge carrier and serious photo corrosion which restricts practical applications for solar energy conversion. In this context, we develop a robust BiVO4 protected with a MoO3 barrier layer, constructing with surface dual-doping engineering, which serves as an outstanding PEC electrode for natural seawater photoelectrolysis. We further demonstrate that the optimized photoelectrode presents a resembled photocurrent density value in simulated seawater and natural seawater under 1 sun AM 1.5G illumination, which shows a strong photocorrosion resistance over 70 h of continuous irradiation, representing one of the targets directly avoiding chloride corrosion on seawater photoelectrolysis.