Controlled syngas production by electrocatalytic CO reduction on formulated Au(SR) and PtAu(SR) nanoclusters.

Syngas, a gaseous mixture of CO and H, is a critical industrial feedstock for producing bulk chemicals and synthetic fuels, and its production via direct CO electroreduction in aqueous media constitutes an important step toward carbon-negative technologies. Herein, we report controlled syngas production with various H/CO ratios via the electrochemical CO reduction reaction (CORR) on specifically formulated Au and PtAu nanoclusters (NCs) with core-atom-controlled selectivities. While CO was predominantly produced from the CORR on the Au NCs, H production was favored on the PtAu NCs. Density functional theory calculations of the free energy profiles for the CORR and hydrogen evolution reaction (HER) indicated that the reaction energy for the conversion of CO to CO was much lower than that for the HER on the Au NC. In contrast, the energy profiles calculated for the HER indicated that the PtAu NCs have nearly thermoneutral binding properties; thus, H production is favored over CO formation. Based on the distinctly different catalytic selectivities of Au and PtAu NCs, controlled syngas production with H/CO ratios of 1 to 4 was demonstrated at a constant applied potential by simply mixing the Au and PtAu NCs based on their intrinsic catalytic activities for the production of CO and H.