  Electrochemical CO2 reduction is a promising strategy for utilization of CO2
and intermittent excess electricity. Cu is the only single-metal catalyst that
can electrochemically convert CO2 to multi-carbon products. However, Cu has an
undesirable selectivity and activity for C2 products, due to its insufficient
amount of CO* for C-C coupling. Considering the strong CO2 adsorption and
ultra-fast reaction kinetics of CO* formation on Pd, an intimate CuPd(100)
interface was designed to lower the intermediate reaction barriers and then
improve the efficiency of C2 products. Density functional theory (DFT)
calculations showed that the CuPd(100) interface has enhanced CO2 adsorption
and decreased CO2* hydrogenation energy barrier, which are beneficial for C-C
coupling. The potential-determining step (PDS) barrier of CO2 to C2 products on
CuPd(100) interface is 0.61 eV, which is lower than that on Cu(100) (0.72 eV).
Motivated by the DFT calculation, the CuPd(100) interface catalyst was prepared
by a facile chemical solution method and demonstrated by transmission electron
microscope (TEM). The CO2 temperature programmed desorption (CO2-TPD) and gas
sensor experiments proved the enhancements of CO2 adsorption and CO2*
hydrogenation abilities on CuPd(100) interface catalyst. As a result, the
obtained CuPd(100) interface catalyst exhibits a C2 Faradaic efficiency of 50.3
(+/-) 1.2% at -1.4 VRHE in 0.1 M KHCO3, which is 2.1 times higher than
23.6(+/-) 1.5% of Cu catalyst. This work provides a rational design of Cu-based
electrocatalyst for multi-carbon products by fine-tuning the intermediate
reaction barriers.
