Efficient photocatalysts of TiO2 nanocrystals-supported PtRu alloy nanoparticles for CO2 reduction with H2O: Synergistic effect of Pt-Ru

Abstract

The photocatalytic reduction of CO2 with H2O to chemical energy-rich molecules (CH4 and CO) is significant to solve energy crisis. Herein, we have successfully fabricated the novel photocatalyst of bimetallic Pt-Ru alloy nanoparticles (NPs) selectively deposited on the {101} facet of TiO2 nanocrystal via the photon-assisted gas bubbling-membrane reduction (P-GBMR) method. The photogenerated electrons and holes are enriched on the coexposed {101}-39% and {001}-61% facets of anatase TiO2 nanocrystal, respectively. Noble metal (Pt, Ru and PtRu) NPs deposited on the TiO2-{101} facet can further improve the separation efficiency of photogenerated electron-hole pairs via the vectorial electron transfer of TiO2→PtRu. Pt/TiO2 catalytst with enriched surface photogenerated electrons shows the relative high formation rate of CH4 (22.9 μmol g−1 h−1) and H2 (52.8 μmol g−1 h−1), while Ru/TiO2 catalyst with strong adsorption/activation capability for CO2 prefers to improve the selectivity to CO product (65.1%). The possible mechanism for CO2 reduction is proposed and discussed: The formation of H-containing intermediate and the adsorption/activation property for CO2 are two important determining steps for improving photocatalytic CO2 reduction with H2O to CH4 product. PtRu/TiO2 catalyst with the synergic effect of Pt and Ru components exhibits the best catalytic performance for CO2 reduction with H2O to CH4 product under simulated solar irradiation, i.e., its formation rate of CH4 (38.7 μmol g−1 h−1) is about 29-fold of commercial P25, its selectivity to CH4 product is 93.7% and its apparent quantum efficiency for CO2 conversion is 0.98%. It expected to be a new heuristic on the development of high efficient photocatalysts for application to light-chemical energy conversion.