Construction of BiOBr nanosheets and oxygen vacancy-rich TiNS heterojunction for efficient photothermal CO2 reduction

Abstract

Utilizing water as an electron donor for the artificial CO₂ photoreduction into valuable chemicals presents a promising way to partially address energy challenges and achieve carbon neutrality. Syngas (CO and H₂) is an ideal platform for synthesizing hydrocarbons and carbonyl compounds, etc., and it can be synthesized from CO₂ reduction. Recently, photothermal catalysis combines the advantages of photocatalysis and thermal catalysis, which is a promising approach to achieving the reaction under relatively mild conditions. In the present work, a catalyst, comprised of titanate nanosheets (TiNS) and BiOBr (BOB), was feasibly prepared and used for photothermal CO₂ reduction, in which water serves as the electron donor. The catalyst delivered CO and H₂ yields of 168 μmol·g_cat⁻¹·h⁻¹ and 219 μmol·g_cat⁻¹·h⁻¹. Notably, the CO yield is 9 times higher than TiNS and 3 times higher than BiOBr alone. Experimental studies and theoretical calculations indicated that the introduction of oxygen vacancies in TiNS significantly provided more active sites for the adsorption and activation of CO₂, while also reducing the energy barrier of the rate-determining step in the CO₂-to-CO reduction. Typically, the 50 wt% BOB/TiNS catalyst exhibited strong adsorption and activation of CO₂ and showed a low barrier for the rate-determining step in the titled reduction. Consequently, the photothermal catalytic CO₂ conversion performance was significantly improved, offering a rational design concept for the photothermal catalytic CO₂ reduction to produce syngas.