Highly Selective Production of Ethanol Over Hierarchical Bi@Bi2MoO6 Composite via Bicarbonate-Assisted Photocatalytic CO2 Reduction

Graphical Photocatalytic CO 2 reduction : Benefiting from the synergistic effect of local high electron density at active sites and thermodynamic bicarbonate assistance, the hierarchical Bi@Bi 2 MoO 6 composite simultaneously shows good photocatalytic CO 2 reduction activity and high ethanol selectivity (92 %). Furthermore, bicarbonate ions play an important role in the formation of long-chain products due to the C−C coupling between derivative carbene intermediates and other carbon-containing intermediates. Photocatalytic CO 2 reduction is a sustainable and inexpensive method to solve the energy crisis and the greenhouse effect. However, the major stumbling blocks such as poor product selectivity, low yield of the multi-carbon products, and serious recombination of electron-hole pairs hinder practical application of photocatalysts. Herein, a high-performance Bi@Bi 2 MoO 6 photocatalyst, Bi nanoparticles grown on the surface of Bi 2 MoO 6 nanosheets with oxygen vacancies, was fabricated via a simple solvothermal approach. Benefiting from the abundant active sites and effective separation of photogenerated carriers of Bi 2 MoO 6 nanosheets, and the localized surface plasmon resonance effect of Bi nanoparticles, the Bi@Bi 2 MoO 6 sample exhibited great photocatalytic CO 2 reduction activity. Furthermore, adding NaHCO 3 into the system not only significantly increased the C 2 H 5 OH generation rate but also enhanced the product selectivity. In the photocatalytic measurement (0.17 mol L −1 CO 2 -saturated NaHCO 3 solution), the highest formation rates of CO, CH 3 OH, and C 2 H 5 OH were reached at 0.85, 0.59, and 17.93 μmol g −1 h −1 (≈92 % selectivity), respectively.