A novel N-doped graphene oxide enfolded reduced titania for highly stable and selective gas-phase photocatalytic CO₂ reduction into CH₄: An in-depth study on the interfacial charge transfer mechanism

A desire for renewable alternatives to fossil fuels can be achieved by utilizing CO₂, H₂O, and solar energy to generate solar fuels. A novel N-doped graphene oxide enfolded reduced titania (NGO-RT) composite was demonstrated for photocatalytic CO₂ reduction into CH₄. Later, a small amount of Pt NPs was deposited on NGO-RT that increases the catalytic performance towards CH₄ formation. The optimized Pt_1.0%-NGO-RT catalyst displayed a selective visible-light CO₂ reduction into CH₄ using a flow reactor system with ≈12 and ≈2 times higher activity than pristine RT and NGO-RT, respectively. The catalyst demonstrated long-term stability over 35 h. The photo-induced CO₂ reduction mechanism was first validated through the electron transfer process, where charge trapping by Ti³⁺ states near the conduction band of RT plays a vital role in the selective CH₄ evolution. These trapped electrons transfer from RT to the closely connected interface of N-doped graphene oxide and Pt NPs to restrict the recombination of electron/hole pair. The improved catalytic performance can be attributed to RT's downward band bending at the NGO-RT interface, where electron transfer from RT to NGO decreases the charge recombination.