Photo-generated high-energy surface states can help to produce chlorine in aqueous environments. Here, aligned rutile (TiO₂) nanocrystal arrays are grown onto fluorine-doped tin oxide (FTO) substrates and activated either by hydrothermal Sr/Ba surface doping and/or by vacuum-annealing. With vacuum-annealing, highly photoactive films are obtained with photocurrents of typically 8 mA cm⁻² at 1.0 V vs. SCE in 1 M KCl (LED illumination with λ = 385 nm and approx. 100 mW cm⁻²). Photoelectrochemical chlorine production is demonstrated at proof-of-concept scale in 4 M NaCl and suggested to be linked mainly to the production of Ti(III) surface species by vacuum-annealing, as detected by post-catalysis XPS, rather than to Sr/Ba doping at the rutile surface. The vacuum-annealing treatment is proposed to beneficially affect (i) bulk semiconductor TiO₂ nanocrystal properties and electron harvesting, (ii) surface TiO₂ reactivity towards chloride adsorption and oxidation, and (iii) FTO substrate performance.

光生高能表面态可以帮助在水性环境中产生氯。在此，将对准的金红石（TiO ₂）纳米晶体阵列生长在掺氟的氧化锡（FTO）衬底上，并通过水热Sr / Ba表面掺杂和/或真空退火进行活化。通过真空退火，在1 M KCl中，相对于SCE，在1.0 V下的光电流通常为8 mA cm ^-2，获得高光敏膜（λ  = 385 nm和约100 mW cm ^-2的LED照明））。在4 M NaCl中以概念验证的规模证明了光电化学氯的产生，并建议将其主要与通过真空退火（如后催化XPS检测）产生的Ti（III）表面物质有关，而不是与Sr /钡掺杂在金红石表面。提出了真空退火处理以有益地影响（i）体半导体TiO ₂纳米晶体特性和电子收集，（ii）表面TiO ₂对氯化物吸附和氧化的反应性，以及（iii）FTO衬底性能。