Cu-phen Coordination Enabled Selective Electrocatalytic Reduction of CO₂ to Methane

Manipulation of selectivity in the catalytic electrochemical carbon dioxide reduction reaction (eCO ₂RR) poses significant challenges due to inevitable structure reconstruction. One approach is to develop effective strategies for controlling reaction pathways to gain a deeper understanding of mechanisms in robust CO ₂RR systems. In this work, by precise introduction of 1,10-phenanthroline as a bidentate ligand modulator, the electronic property of the copper site was effectively regulated, thereby directing selectivity switch. By modification of [Cu ₃(btec)(OH) ₂] _n, the use of [Cu ₂(btec)(phen) ₂] _n·(H ₂O) _n achieved the selectivity switch from ethylene (faradaic efficiency (FE) = 41%, FE _C2+ = 67%) to methane (FE _{CH 4} = 69%). Various in situ spectroscopic characterizations revealed that [Cu ₂(btec)(phen) ₂] _n·(H ₂O) _n promoted the hydrogenation of *CO intermediates, leading to methane generation instead of dimerization to form C ₂₊ products. Acting as a delocalized π-conjugation scaffold, 1,10-phenanthroline in [Cu ₂(btec)(phen) ₂] _n·(H ₂O) _n helps stabilize Cu ^δ+. This work presents a novel approach to regulate the coordination environment of active sites with the aim of selectively modulating the CO ₂RR.