Switching Products Selectivity in Electrocatalytic C(sp 3 )─H Bonds Activation and CO 2 Carboxylation via Cu─S Bond Crystal Engineering

Inert C(sp³)─H bonds activation along with CO₂ carboxylation to prepare high-value carboxylic acids is a sustainable route for achieving the carbon-neutral goal, but the current catalytic performance is far from satisfying the demand. Targeting this problem, it was found that crystal engineering of Cu─S bonds not only significantly enhanced the activity of C(sp³)─H activation and CO₂ carboxylation in an electrocatalytic system, but also efficiently realized chemoselectivity in the CO₂ carboxylation process. Specifically, hexagonal CuS(001) electrocatalyst could readily achieve C(sp³)─H bond activation of alkanes and aromatics along with CO₂ carboxylation, exhibiting almost complete chemoselectivity to carbon chain increased monocarboxylation acids. Intriguingly, hexagonal Cu₂S(110) electrocatalyst, which was prepared by phase transition, could realize highly selective alkanes and aromatics dicarboxylation with CO₂ to produce dicarboxylation acids. Notably, biomass compound 2-methylfuran was efficiently converted into furan-2-acetic acid over CuS(001); while 2,5-dimethylfuran was quantitatively converted to the degradable polymer precursor furan-2,5-dicarboxylic acid over Cu₂S(110). Moreover, density functional theory (DFT) results revealed the origin of differences in the activity and chemoselectivity over CuS(001) and Cu₂S(110) catalysts.