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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.

Ethanol is a green, sustainable, and high-energy-density liquid fuel that holds great promise for direct liquid fuel cells (DLFCs). However, it remains highly challenging to develop electrocatalysts that selectively promote the C–C bond scission for the ethanol oxidation reaction (EOR). Here, we report the facile synthesis of PtIr alloy core–shell nanocubes (NCs) with Ir-rich shells as effective EOR electrocatalysts. We find that (100)-exposed Pt38Ir NCs with one-atom-thick Ir-rich skin exhibit unprecedented EOR activity, high CO2 selectivity, and long-term stability, while pure Pt NCs and Pt17Ir NCs (two-atom thick Ir-rich skin) show less activity and lower CO2 selectivity. We demonstrate that the Pt38Ir NCs electrocatalyst can deliver a current density up to 4.5 times higher than that of Pt/C with a lower EOR onset potential by 320 mV. Its CO2 current density at 0.85 V is 14 times higher than that of commercial Pt/C. We show that the enhanced EOR activity is mainly due to the Ir-rich PtIr(100) facet that not only favors the splitting of the C–C bond by strongly adsorbing the *C x H y O/C x H y species but also promotes the desorption of CO from the PtIr surface. This work highlights the critical role of surface atom layers on shape-engineered catalysts and demonstrates a strategy for the design of efficient EOR electrocatalysts.

The oxygen evolution reaction (OER) has broad applications in electrochemical devices, but it often requires expensive and scarce Ir-based catalysts in acid electrolyte. Presented here is a framework to reduce Ir loading by combining core–shell iridium/metal nitride morphologies using in situ experiments and density functional theory (DFT) calculations. Several group VIII transition metal (Fe, Co, and Ni) nitrides are studied as core materials, with Ir/Fe4N core–shell particles showing enhancement in both OER activity and stability. In situ X-ray absorption fine structure measurements are used to determine the structure and stability of the core–shell catalysts under OER conditions. DFT calculations are used to demonstrate adsorbate binding energies as descriptors of the observed activity trends.

Electrochemical CO2 reduction reaction (CO2RR) with renewable electricity is a potentially sustainable method to reduce CO2 emissions. Palladium supported on cost‐effective transition‐metal carbides (TMCs) are studied to reduce the Pd usage and tune the activity and selectivity of the CO2RR to produce synthesis gas, using a combined approach of studying thin films and practical powder catalysts, in situ characterization, and density functional theory (DFT) calculations. Notably, Pd/TaC exhibits higher CO2RR activity, stability and CO Faradaic efficiency than those of commercial Pd/C while significantly reducing the Pd loading. In situ measurements confirm the transformation of Pd into hydride (PdH) under the CO2RR environment. DFT calculations reveal that the TMC substrates modify the binding energies of key intermediates on supported PdH. This work suggests the prospect of using TMCs as low‐cost and stable substrates to support and modify Pd for enhanced CO2RR activity.