Tuning the activity and selectivity of electroreduction of CO ₂ to synthesis gas using bimetallic catalysts

Abstract

The electrochemical carbon dioxide reduction reaction to syngas with controlled CO/H ₂ ratios has been studied on Pd-based bimetallic hydrides using a combination of in situ characterization and density functional theory calculations. When compared with pure Pd hydride, the bimetallic Pd hydride formation occurs at more negative potentials for Pd-Ag, Pd-Cu, and Pd-Ni. Theoretical calculations show that the choice of the second metal has a more significant effect on the adsorption strength of *H than *HOCO, with the free energies between these two key intermediates (i.e., ΔG(*H)–ΔG(*HOCO)) correlating well with the carbon dioxide reduction reaction activity and selectivity observed in the experiments, and thus can be used as a descriptor to search for other bimetallic catalysts. The results also demonstrate the possibility of alloying Pd with non-precious transition metals to promote the electrochemical conversion of CO ₂ to syngas.

Abstract

Converting solar energy to hydrogen fuel requires light-absorbers that well-match the wavelengths of incoming sunlight. Here, authors prepare a broadband visible-light-absorbing molecular complex that efficiently produces hydrogen from water.