A highly active nickel electrocatalyst shows excellent selectivity for CO reduction in acidic media.

The development of selective electrocatalysts for CO reduction in water offers a sustainable route to carbon based fuels and feedstocks. However, molecular catalysts are typically studied in non-aqueous solvents, in part to avoid competitive H evolution. [Ni(cyclam)] () is one of the few known electrocatalysts that operate in water and 30 years after its report its activity remains a rarely surpassed benchmark. Here we report that [Ni(cyclam-COH)] (cyclam-COH = 1,4,8,11-tetraazacyclotetradecane-6-carboxylic acid ()) shows greatly enhanced activity for CO production. At pHs < p of the pendant carboxylic acid a large increase in catalytic activity occurs. Remarkably, despite the high proton concentration (pH 2), maintains selectivity for CO reduction and is believed to be unique in operating selectively in such acidic aqueous solutions.