Boosting Formate Production from CO2 at High Current Densities Over a Wide Electrochemical Potential Window on a SnS Catalyst

The flow-cell design offers prospect for transition to commercial-relevant high current density CO2 electrolysis. However, it remains to understand the fundamental interplay between the catalyst, and the electrolyte in such configuration toward CO2 reduction performance. Herein, the dramatic influence of electrolyte alkalinity in widening potential window for CO2 electroreduction in a flow-cell system based on SnS nanosheets is reported. The optimized SnS catalyst operated in 1 m KOH achieves a maximum formate Faradaic efficiency of 88 ± 2% at -1.3 V vs reversible hydrogen electrode (RHE) with the current density of ≈120 mA cm-2 . Alkaline electrolyte is found suppressing the hydrogen evolution across all potentials which is particularly dominant at the less negative potentials, as well as CO evolution at more negative potentials. This in turn widens the potential window for formate conversion (>70% across -0.5 to -1.5 V vs RHE). A comparative study to SnOx counterpart indicates sulfur also acts to suppress hydrogen evolution, although electrolyte alkalinity resulting in a greater suppression. The boosting of the electrochemical potential window, along with high current densities in SnS derived catalytic system offers a highly attractive and promising route toward industrial-relevant electrocatalytic production of formate from CO2 .

Durable Cathodes and Electrolyzers for the Efficient Aqueous Electrochemical Reduction of CO2

The world emits over 14 gigatons of CO₂ in excess of what can be remediated by natural processes annually, contributing to rising atmospheric CO₂ levels and increasing global temperatures. The electrochemical reduction of CO₂ (CO₂ RR) to value-added chemicals and fuels has been proposed as a method for reusing these excess anthropogenic emissions. While state-of-the-art CO₂ RR systems exhibit high current densities and faradaic efficiencies, research on long-term electrode durability, necessary for this technology to be implemented commercially, is lacking. Previous reviews have focused mainly on the CO₂ electrolyzer performance without considering durability. In this Review, the need for research into high-performing and durable CO₂ RR systems is stressed by summarizing the state-of-the-art with respect to durability. Various failure modes observed are also reported and a protocol for standard durability testing of CO₂ RR systems is proposed.