Correlating Oxidation State and Surface Ligand Motifs with the Selectivity of CO₂ Photoreduction to C₂ Products

Abstract

The design for non-Cu-based catalysts with the function of producing C 2 + products requires systematic knowledge of the intrinsic connection between the surface state as well as the catalytic activity and selectivity. In this work, photochemical in situ spectral surface characterization techniques combined with the first principle calculations (DFT) were applied to investigate the relationships between the composition of surface states, coordinated motifs, and catalytic selectivity of a titanium oxynitride catalyst. When the catalyst mediates CO 2 photoreduction, C 2 product selectivity is positively correlated with the surface Ti 2 + /Ti 3 + ratio and the surface oxidation state is regulated and controlled by coordinated motifs of NÀ Ti-O/V [O], which can reduce the potential dimerization energy barriers of *COÀ CO* and promote spontaneous formation of the subsequent *COÀ CH 2 * intermediate. This phenomenon provides a new perspective for the design of heterogeneous catalysts for photoreduction of CO 2 into useful products.

Materials Design for Photocatalytic CO2 Conversion to C2+ Products

“…As a consequence of this removal, coordinatively unsaturated metal atoms with a reduced valence state are generated. Interestingly, these coordinatively unsaturated metal atoms can serve not only as electron reservoirs, but also as an active site for intermediate stabilization and the subsequent C–C coupling. − For instance, Dai et al conducted a study on the preparation of a three-dimensional (3D) Bi 2 MoO 6 material with oxygen vacancies for photocatalytic CO 2 conversion (Figure a,b) . Their research revealed that these oxygen vacancies played a crucial role in enhancing the separation efficiency of photogenerated charge carriers within the Bi 2 MoO 6 structure, while also serving as active sites for trapping CO 2 molecules.…”

Organic polymer facilitated CO2 photoreduction: a minireview

“…Generally, fundamental photocatalytic CO 2 reduction follows these steps: (i) light absorption; (ii) formation of photo-induced electrons (e − ) and holes (h + ); (iii) transfer of e − to the surface of the catalyst; and (iv) reduction of the adsorbed CO 2 promoted by these electrons. 32–35 As shown in Fig. 2, the produced e − migrate to the conduction band (CB) from the valence band (VB), resulting in the generated e − and h + serving as the active sites of the redox reaction, respectively.…”