Carbon dioxide (CO₂) electroreduction offers an attractive pathway for converting CO₂ to valuable fuels and chemicals. Despite the existence of some excellent electrocatalysts with superior selectivity for specific products, these reactions are conducted at low current densities ranging from several mA cm⁻² to tens of mA cm⁻², which are far from commercially desirable values. To extend the applications of CO₂ electroreduction technology to an industrial scale, long-term operations under high current densities (over 200 mA cm⁻²) are desirable. In this paper, we review recent major advances toward higher current density in CO₂ reduction, including: (1) innovations in electrocatalysts (engineering the morphology, modulating the electronic structure, increasing the active sites, etc.); (2) the design of electrolyzers (membrane electrode assemblies, flow cells, microchannel reactors, high-pressure cells, etc.); and (3) the influence of electrolytes (concentration, pH, anion and cation effects). Finally, we discuss the current challenges and perspectives for future development toward high current densities.

Due to CO₂ mass transfer limitation as well as the competition of hydrogen evolution reaction in electroreduction of CO₂ in the aqueous electrolyte, Zn-based electrodes normally exhibit unsatisfying selectivity for CO production, especially at high potentials. In this work, we introduced a zinc myristate (Zn [CH₃(CH₂)₁₂COO]₂) hydrophobic layer on the surface of zinc foam electrode by an electrodeposition method. The obtained hydrophobic zinc foam electrode showed a high Faradaic efficiency (FE) of 91.8% for CO at −1.9 V (vs. saturated calomel electrode, SCE), which was a remarkable improvement over zinc foam (FE_CO = 81.87%) at the same potentials. The high roughness of the hydrophobic layer has greatly increased the active surface area and CO₂ mass transfer performance by providing abundant gas-liquid-solid contacting area. This work shows adding a hydrophobic layer on the surface of the catalyst is an effective way to improve the electrochemical CO₂ reduction performance.