Unravelling intrinsic descriptors based on a two-stage activity regulation of bimetallic 2D c-MOFs for CO 2 RR.

The bimetallic 2D conductive MOFs of M 1 Pc-M 2 -O, possessing dual metal sites to realize flexible molecular-level structural modification, are brilliant catalysts for electrochemical CO 2 reduction. However, the bimetallic centers bring about the complex regulatory mechanism of catalytic activity and obscure principles for catalyst design. Herein, systematical theoretical investigation unravels intrinsic descriptors to design favorable M 1 Pc-M 2 -O catalysts based on the discovered coarse-fine two-stage activity regulation mechanism. The reaction site controls the M-COOH distance of the key intermediate and therefore affects the reaction kinetics for the first stage of coarse regulation. The other metal site influents the d-band center of the reaction site and thus constitutes the second stage of fine regulation. The coarse and fine regulation are related to the valence electrons ( V ), electronegativity ( E ), and bond length ( L M-N/O ) between the metal and coordination atoms. The intrinsic descriptor ϕ = (4 × V M 1 × ( E M 1 + E N/O )/ E N/O + V M 2 × ( E M 2 + E N/O )/ E N/O ) × L M 1 -N/O (with a coefficient ratio of 4 : 1) was eventually established and correlated well with the reported experiments. On this basis, the favorable catalysts CoPc-Zn-O and CoPc-Co-O were located. The research results could contribute to the diversity of bimetallic 2D c-MOFs in CO 2 RR.