Indium-modified copper nanocubes for syngas production by aqueous CO₂ electroreduction

Electroreduction of carbon dioxide represents an appealing strategy to rethink a waste product as a valuable feedstock for the formation of value-added compounds. Among the metal electrodes able to catalyze such processes, copper plays a central role due to its rich chemistry. Strategies aimed at tuning Cu selectivity comprise nanostructuring and alloying/post-functionalization with heterometals. In this contribution, we report on straightforward electrochemical methods for the formation of nanostructured Cu-In interfaces. The latter were fully characterized and then used as cathodes for CO₂ electroreduction in aqueous environment, leading to the selective production of syngas, whose composition varies upon changing the applied bias and indium content. In particular, gaseous mixtures compatible with the synthesis of methanol or aldehydes (i.e. respectively with 1 : 2 and 1 : 1 CO/H₂ ratios) are produced at low (i.e. -0.62 V vs. RHE) applied bias with >3.5 mA cm^-2 current densities (in absolute value). Even if the proposed cathodes undergo structural modifications upon prolonged exposure to CO₂ reduction conditions, their catalytic activity can be restored by introducing an additional In(III) precursor to the electrolytic solution.