Selective photocatalytic reduction of CO2 into CH4 over Pt-Cu2O TiO2 nanocrystals: The interaction between Pt and Cu2O cocatalysts

Photocatalytic reduction of CO2 with water is one of the most popular and challenging technologies to produce renewable energy. In this paper, Pt and Cu2O nanoparticles (NPs) were deposited on the surface of anatase TiO2 nanocrystals, and their effects on the photocatalytic performance of TiO2 were thoroughly studied. Based on experimental results, Pt tended to promote the production of CH4 and H2. However, Cu2O suppressed H2 production and exhibited lower CH4 selectivity than that of Pt. Furthermore, when Pt and Cu2O were co-deposited on TiO2 crystals, H2 production was inhibited and CO2 was selectively converted into CH4. From characterization, we found that Pt could not only capture photogenerated electrons and but also increase the electrons density on the catalyst, which were beneficial for selective CH4 formation. In addition, co-deposited Cu2O enhanced the CO2 chemisorption on TiO2 while inhibited that of water, resulting in enhancement of CO2 reduction and lower H2 production. On account of the above-mentioned contribution of Pt and Cu2O NPs, Pt-Cu2O/TiO2 catalyst showed high CH4 selectivity towards all products from reductive reaction.