Promoting photocatalytic CO2 reduction to CH4 via a combined strategy of defects and tunable hydroxyl radicals.

[Display omitted] • A combined strategy of defects and tunable hydroxyl radical was designed for CO 2 photoreduction. • Highly dispersed Bi 2 Ti 2 O 7 was introduced in defective TiO 2 via an in situ topochemical reactions etching route. • CO 2 photoreduction rate for CH 4 of optimized heterophase is 7.9 times higher than that of P25. A well-designed photocatalyst with excellent activity and selectivity is crucial for photocatalytic CO 2 conversion and utilization. TiO 2 is one of the most promising photocatalysts. However, its excessive surface oxidation potential and insufficient surface active sites inhibit its activity and photocatalytic CO 2 reduction selectivity. In this work, highly dispersed Bi 2 Ti 2 O 7 was introduced into defective TiO 2 to adjust its oxidation potential and the generation of radicals, further inhibiting reverse reactions during the photocatalytic conversion of CO 2. Moreover, an in situ topochemical reaction etching route was designed, which achieved defective surfaces, a contacted heterophase interface, and an efficient electron transfer path. The optimized heterophase photocatalyst exhibited 93.9% CH 4 selectivity at a photocatalytic rate of 6.8 μmol·g−1·h−1, which was 7.9 times higher than that of P25. This work proposes a feasible approach to fabricating photocatalysts with well-designed band structures, highly dispersed heterophase interfaces, and sufficient surface active sites to effectively modulate the selectivity and activity of CO 2 photoreduction by manipulating the reaction pathways. [ABSTRACT FROM AUTHOR]