Syngas production by electrochemical CO2 reduction in an ionic liquid based-electrolyte

•Efficient, scalable eco-friendly process for cathode preparation for CO2 reduction.•Deep eutectic solvents plating baths allow wide range composition of Cu-Zn cathodes.•CO faradaic efficiency increases with Zn content of the alloy for Zn >40 at.% at 30 bar/45 °C.•Low carbon footprint syngas produced by Cu-Zn alloys with H2/CO tuning capability.•Syngas produced with low energy requirements using Zn-Cu alloys/ionic liquid.

The electrochemical reduction of carbon dioxide dissolved in a solution of water and ionic liquid as electrolyte, at high-pressure and near room-temperature, is reported. This work describes an electro-deposition strategy for the preparation of copper substrate cathodes, coated with bimetallic zinc-copper films, obtained from deep-eutectic solvents plating baths. The prepared bimetallic cathodes showed electrochemical activity for syngas production in 1-butyl-3-methylimidazolium triflate, with yields of 85 NμL (normal microliter) cm−2 C−1/170 NμL cm−2 h−1, high selectivities, tunable H2/CO ratio and low energetic requirements.

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