Room-temperature photosynthesis of propane from CO 2 with Cu single atoms on vacancy-rich TiO 2 .

Photochemical conversion of CO 2 into high-value C 2+ products is difficult to achieve due to the energetic and mechanistic challenges in forming multiple C-C bonds. Herein, an efficient photocatalyst for the conversion of CO 2 into C 3 H 8 is prepared by implanting Cu single atoms on Ti 0.91 O 2 atomically-thin single layers. Cu single atoms promote the formation of neighbouring oxygen vacancies (V O s) in Ti 0.91 O 2 matrix. These oxygen vacancies modulate the electronic coupling interaction between Cu atoms and adjacent Ti atoms to form a unique Cu-Ti-V O unit in Ti 0.91 O 2 matrix. A high electron-based selectivity of 64.8% for C 3 H 8 (product-based selectivity of 32.4%), and 86.2% for total C 2+ hydrocarbons (product-based selectivity of 50.2%) are achieved. Theoretical calculations suggest that Cu-Ti-V O unit may stabilize the key *CHOCO and *CH 2 OCOCO intermediates and reduce their energy levels, tuning both C 1 -C 1 and C 1 -C 2 couplings into thermodynamically-favourable exothermal processes. Tandem catalysis mechanism and potential reaction pathway are tentatively proposed for C 3 H 8 formation, involving an overall (20e - - 20H + ) reduction and coupling of three CO 2 molecules at room temperature.