Non-trivial topological surface states regulation of 1 T-OsCoTe2 enables selective C―C coupling for highly efficient photochemical CO2 reduction toward C2+ hydrocarbons

Despite ongoing research, the rational design of non-trivial topological semimetal surface states for the selective photocatalytic CO 2 conversion into valuable products remains full of challenges. Herein, we present the synthesis of lattice-matched 1 T-OsCoTe 2 for the photoreduction upgrading of CO 2 to tri-carbon (C 3 ) alkane (propane, C 3 H 8 ) by the integration of experimental work and theory prediction/calculation. Experimental studies suggested a high electron-based selectivity of 71.2 % for C 3 H 8 and an internal quantum efficiency of 54.6 % at 380 nm. In-situ X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy demonstrated that Co and Os atoms coordinated with Te atoms enable an efficient Os―Te―Co electron transfer to activate the generation of *CH 3 , *CHOCO and *CH 2 OCOCO. Density functional theory calculations further confirmed Os―Te―Co electron bridging on the improved CO 2 conversion kinetics. To our knowledge, this is the first report suggesting the role of Os atoms in accelerating the photocatalytic CO 2 conversion activity of the topological semimetal 1 T-OsCoTe 2 .