Reduction reactions versus hydrogen

A reduction reaction is half an overall electrochemical process and hydrogen evolution reaction (HER) is the simplest electrocatalytic reduction reaction. Beyond hydrogen, other reduction reactions are more complex with species involved, products formed, and selectivity typically changes as a function of catalyst and potential. This work seeks to provide a combined view on electrocatalytic CO2/CO reduction, NOx reduction and N2 reduction which are all reduction reactions in competition with HER. The thermodynamics of the reactions are compared together with selectivity predictive schemes for aqueous conditions. Recent experimental results are discussed for the three reduction reactions from a predictive theoretical catalytic mindset, which indicate that dissociation mechanisms have entered electrocatalysis for certain catalytic systems at ambient conditions.