Engineering of Ti/V bimetallene for selectivity boosting the photocatalytic carbon dioxide hydrogenation reaction.

• Bimetallic nitride heterostructures is constructed to broaden the optical response. • The C@VN/TiN sample are synthesized by ammonia-assisted one-step calcination. • The C@VN/TiN sample has the best photoreduction CO 2 performance. There are still many challenges in inhibiting the recombination and differentiation of photogenerated carriers from promoting the conversion of CO 2 into hydrocarbons. Based on the functional differentiation of different metal sites, bimetallic nitride heterostructures is constructed to broaden the optical response and promote the separation of charge carriers in this work. Herein, carbon substrate-loaded double nitride heterostructure composites C@VN/TiN are synthesized by ammonia-assisted one-step calcination. In all samples, the C@VN/TiN-3 sample has the best photoreduction CO 2 performance with the promotion of lactic acid (LA) reagent. And the CH 4 yield of the C@VN/TiN-3 sample is 775 μmol g−1 h-1, which is 7.6 times and 10.3 times higher than C@VN (102 μmol g−1 h-1) and C@TiN (75 μmolg−1 h-1), respectively. The generation, separation, and migration of photogenerated electron-hole pairs are studied kinetically through transient photocurrent responses, electrochemical impedance spectroscopy and photoluminescence spectroscopy. The position and process of adsorption and activation of CO 2 and H 2 O are deduced by in situ characterization and reaction potential, and the determined possible path is explored by the peak of intermediates. This paper reveals the important roles of co-catalytic agents, ohmic junctions, and the function of bimetallic actives in enhancing photocatalytic activity, providing new ideas for constructing efficient photocatalysts. [ABSTRACT FROM AUTHOR]