Alcohol Plasma Processed Surface Amorphization for Photocatalysis

Plasma processing of photocatalysts can conveniently change the surface chemistry, introducing extrinsic or intrinsic surface doping, holding promise to make photocatalysts more active without altering the bulk properties. While gas plasma has long been employed to process photocatalysts, it is hard to avoid the surface dry etching caused by the high-energy charged ions in the plasma with a long mean free path, which results in excessive defects or even deactivation dependent on the kind of photocatalyst. Herein, we propose an innovative alcohol solution plasma approach to process the benchmarked Degussa P25-TiO2 photocatalyst. By virtue of the short mean free path of charged ions in the solution phase, high plasma density, and additional hydrogen doping, the alcohol plasma processing renders the surface amorphization of TiO2 particles and diminishes surface oxygen vacancies. A 124-fold increase of photocatalytic H2 evolution is achieved after alcohol solution plasma processing, which is attributed to the surface-amorphization-induced decrease in surface deep electron traps and upshifted energy level of electron traps. The alcohol solution plasma processing also outperforms water plasma processing and highlights a promising strategy of modulation of surface electronic properties for photocatalysis.