Theoretical insight into the role of organic ligands and metal centers on electrocatalytic hydrogen evolution activity in two-dimensional metal-organic frameworks

Two-dimensional (2D) metal-organic frameworks (MOFs) have attracted considerable attentions in catalysis due to their exceptional high porosity and chemical tunability. By tuning metal centers and organic ligands, it is possible to precisely control the electronic structure of MOFs, offering a promising strategy to enhance catalytic performance. In this study, we performed theoretical investigations into four 2D MOFs: Cu-1,4-dicyanobenzene (Cu-DCB), Cu-1, 3-dicyanobenzene (Cu-DCB'), Cu-1,1':4',1''-terphenyl]-4,4''-dicarbonitrile (Cu-TPDCN), Cu-1,1':3',1''-terphenyl]-4,4''-dicarbonitrile (Cu-TPDCN'). Our calculations reveal that all the four MOFs exhibit metallic properties, but only Cu-DCB' and Cu-TPDCN' frameworks have negative adsorption energies for hydrogen ions. Upon replacing the Cu atoms with Ni, the Ni-based frameworks exhibit semiconducting behavior, and surprisingly, all show negative adsorption energies for hydrogen. This is attributed to the bond order tunability of C-N bonds during hydrogen adsorption in Ni-based nanostructures. Furthermore, the Gibbs free energy of hydrogen in the Ni-DCB framework is significantly reduced to -0.03 eV. These findings indicate that metal substitution is an effective strategy to enhance the electrocatalytic performance of hydrogen evolution reactions. This work introduces a novel approach for optimizing the catalytic activity of 2D MOFs and developing high-performance catalysts.