Na-Ru bimetallic functional sites promote photo-driven CO2 directed conversion into CH4

Recently, there has been a significant increase in interest in using photocatalysis for the energy conversion of polluting gases. In this research, sodium and ruthenium bimetallic functional sites co-modified bismuth tungstate (Ru/Na-Bi2WO6) nanoflower photocatalyst was synthesized via the hydrothermal method. The CO2 reduction products on the Bi2WO6 substrate were CO (1.66 μmol/g/h, 68 %) and CH4 (0.78 μmol/g/h, 32 %). After optimization, a significant change in the CO2 products of the Bi2WO6-based composite material was observed, with CO (0.61 μmol/g/h, 3.6 %) and CH4 (16.1 μmol/g/h, 96.4 %). Results showed that the dominance of CH4 as the main product in the Ru/Na-BWO system is attributed to the effective doping of Na, which generates impurity energy levels composed of oxygen vacancies, lowering the conduction band position of Bi2WO6, thereby suppressing CO generation, and enhancing CH4 selectivity by changing the CO2 activation pathway. The remarkable performance is ascribed to the synergized adsorption and activation of CO2 by the tandem Na+ sites and Ru0 sites. Specifically, the doped Na+ sites play a major role in promoting the adsorption CO2 molecules, while the Ru0 sites play a dominant role in facilitating the activation of the intermediates.