Electrocatalytic Investigations into a PdNi Nanostructured Alloy Supported over a Graphite Sheet toward Pt-like Hydrogen Evolution Activity

Hydrogen desorption applications over Pd are strongly hindered due to the strong affinity of Pd metal for hydrogen, and thus, exploring Pd-centered hydrogen evolution reaction (HER) catalysts in place of Pt-based materials remains a challenge. Bimetallic alloying could modify the binding energy of metals at the alloy surface for optimum adsorption/desorption of reaction intermediates and an ultimately fast rate of the HER process. Here, a series of PdNi alloy film electrodes of varying thickness was prepared on a graphite substrate by directing the deposition time following a single-step aerosol-assisted chemical vapor deposition method. The structure and morphology of the deposited alloy films were characterized using X-ray, spectroscopic, and microscopy-based techniques. The results confirm the formation of a highly pure PdNi alloyed nanostructure. The electrocatalytic efficiency of the developed films was tested by monitoring the hydrogen evolution reaction under acidic conditions. The PdNi alloy film obtained after a 2 h deposition time demonstrated the best catalytic activity with an overpotential of only 20 mV at a current density of 10 mA cm–2 and a Tafel value of 50.2 mV/dec, a small charge transfer resistance of just 1.2 Ω, and a high turnover frequency and Jexc of 0.83 s–1@0.2 V and 10.69 mA cm–2, respectively. The developed electrodes also demonstrated good chemical and mechanical stability for 22 h in a durability test operating at 100 and 200 mA cm–2. The results are comparable to the state-of-the-art Pt-based HER catalyst investigated under similar circumstances. The remarkably increased electroactive sites on the bimetallic alloy with reasonable binding energies and synergistic interactions between the nanostructured PdNi alloy and the graphite support could cumulatively enhance the electrochemical activity for HER under employed conditions.