Surface-Alkalinization-Induced Enhancement of Photocatalytic H<sub>2</sub> Evolution over SrTiO<sub>3</sub>-Based Photocatalysts

A strategy of reaction-environment modulation was employed to change the surface property of a semiconductor photocatalyst to enhance its photocatalytic performance. Surface alkalinization induced by a high alkalinity of the solution environment significantly shifted the surface energy band of a SrTiO<sub>3</sub> photocatalyst to a more negative level, supplying a strong potential for H<sub>2</sub>O reduction and consequently promoting the photocatalytic efficiency of H<sub>2</sub> evolution. This mechanism is also applicable for visible-light-sensitive La,Cr-codoped SrTiO<sub>3</sub> photocatalyst, which hence, could achieve a high apparent quantum efficiency of 25.6% for H<sub>2</sub> evolution in CH<sub>3</sub>OH aqueous solution containing 5 M NaOH at an incident wavelength of 425 ± 12 nm.