Regulating H₂/CO Ratios in Syngas via CO₂ Electroreduction with the Silver–Nickel Bimetallic Electrocatalyst in a Solid-Electrolyte Membrane Electrode Assembly

The electrocatalytic reduction of CO2 to syngas as a feedstock for the downstream production of economically valuable chemical products represents a promising strategy for the cyclic and effective utilization of CO2. By constructing a bimetallic Ag/Ni heterointerface, electron transfer occurs at the interface due to the difference in electronegativity between silver and nickel metals. This electron transfer causes the electrons of Ni to shift toward silver, thereby tuning the d-band center of both metals and altering the adsorption capability of the bimetallic AgNi toward intermediates, thus controlling H2/CO ratios in syngas. By variation of the ratio of the two metals in the bimetallic catalyst AgxNi1, the extent of electron transfer at the heterointerface of the bimetals can be altered. Consequently, in a solid-electrolyte membrane electrode assembly (MEA), the current density of the bimetallic catalyst Ag8Ni1 can reach 142 mV cm–2 at an electrolysis cell voltage of 4 V, and the bimetallic catalyst is capable of controlling the syngas ratio (H2/CO) within the range of 0.12–0.84. This work provides a new approach to develop high-performance bimetallic catalysts used in solid-electrolyte MEA for future industrial applications.