Unconventional strategies to break through the efficiency of light-driven water splitting: A review

Semiconductor-based solar-driven water splitting technology is an environmentally friendly and cost-effective approach for the production of clean fuels. The overall solar-to-hydrogen efficiency of semiconductor-based photo(electro)catalysts is jointly determined by factors, such as light absorption efficiency of the photo(electro)catalysts, internal separation efficiency of charge carriers, and injection efficiency of surface charges. However, the traditional improvement strategies, such as morphology control, functional layer modification, and band alignment engineering, still have certain limitations in enhancing the conversion efficiency of the photo(electro)catalytic water splitting. Recently, unconventional enhancement strategies based on surface plasmonic effects, piezoelectric effects, thermoelectric effects, and magnetic effects have provided unique pathways for improving the solar-to-hydrogen efficiency of photo(electro)catalysts. Therefore, this review outlines the fundamental concepts of these physical effects and elucidates their intrinsic mechanisms in enhancing the efficiency of photo(electro)catalysts for water splitting process through practical application examples. Ultimately, the future development of unconventional strategies for enhancing photo(electro)catalytic water splitting is envisioned.