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

The photocatalytic reduction of CO 2 with H 2 O to chemical energy-rich molecules (CH 4 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 TiO 2 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 TiO 2 nanocrystal, respectively. Noble metal (Pt, Ru and PtRu) NPs deposited on the TiO 2 -{101} facet can further improve the separation efficiency of photogenerated electron-hole pairs via the vectorial electron transfer of TiO 2 →PtRu. Pt/TiO 2 catalytst with enriched surface photogenerated electrons shows the relative high formation rate of CH 4 (22.9 μmol g −1  h −1 ) and H 2 (52.8 μmol g −1  h −1 ), while Ru/TiO 2 catalyst with strong adsorption/activation capability for CO 2 prefers to improve the selectivity to CO product (65.1%). The possible mechanism for CO 2 reduction is proposed and discussed: The formation of H-containing intermediate and the adsorption/activation property for CO 2 are two important determining steps for improving photocatalytic CO 2 reduction with H 2 O to CH 4 product. PtRu/TiO 2 catalyst with the synergic effect of Pt and Ru components exhibits the best catalytic performance for CO 2 reduction with H 2 O to CH 4 product under simulated solar irradiation, i.e., its formation rate of CH 4 (38.7 μmol g −1  h −1 ) is about 29-fold of commercial P25, its selectivity to CH 4 product is 93.7% and its apparent quantum efficiency for CO 2 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. [ABSTRACT FROM AUTHOR]