Monolayer palladium supported on molybdenum and tungsten carbide substrates as low-cost hydrogen evolution reaction (HER) electrocatalysts

Active and low-cost hydrogen evolution reaction (HER) electrocatalysts are needed to minimize capital costs associated with large-scale hydrogen production from water electrolysis. Catalysts based on monolayer (ML) amounts of precious metals supported on carbides are a promising concept for this purpose. In the current study Pd supported on tungsten carbide (WC) and molybdenum carbide (Mo2C) were evaluated for HER activity. Carbide foils were synthesized using temperature programmed reaction of W or Mo in a CH4/H2 atmosphere. Physical vapor deposition was used to deposit Pd on WC or Mo2C while X-ray Photoelectron Spectroscopy (XPS) was used to determine the Pd surface coverage. Linear sweep voltammetry and chronopotentiometry were used to evaluate the HER activity and electrochemical stability of the catalysts, demonstrating the possibility of using ML Pd on either WC or Mo2C as active, stable and lower-cost HER catalysts.

► We modify Mo and W carbide with Pd to enhance their activity for hydrogen evolution.
► Pd grows in a layer-by-layer fashion on the carbides.
► Nearly two orders of magnitude improvement in activity was observed.
► Very little decrease in the Pd coverage was observed after electrochemistry.