Selective Electrocatalytic Hydrodimerization of Acetylene to 1,3-Butadiene Over Neighboring Cu Dual Sites

Selective electrocatalytic hydrodimerization of acetylene to 1,3-butadiene is a promising alternative to the energy-intensive naphtha steam cracking route, but remains a grand challenge due to competitive acetylene semihydrogenation and oligomerization. Herein, we profoundly investigate the underpinning structure–performance correlations between diverse nuclear number of Cu sites and acetylene hydrodimerization over benchmark Cu-MOFs electrocatalysts. The operando electrochemical Raman and Fourier transform infrared spectroscopies and theoretical simulations together reveal that single Cu site and double Cu sites are favorable for acetylene semihydrogenation and hydrodimerization, respectively. The as-designed neighboring Cu dual sites in trinuclear Cu₃-MOF enable the adsorption of acetylene, subsequent C–C coupling of *C₂H₂ and *C₂H₃ intermediates into 1,3-butadiene as well as the desorption of 1,3-butadiene. As a result, the trinuclear Cu₃-MOF affords a 1,3-butadiene selectivity of 91% and a high 1,3-butadiene production rate of 64 mmol g⁻¹ h⁻¹, which is about 2-fold and 20-fold higher than Cu₂-MOF and Cu₁-MOF. This work not only provides profound insights into the electrocatalytic mechanism of acetylene hydrodimerization but also guides the rational design of high-activity electrocatalysts.