Facile fabrication of binary copper–palladium alloy thin film catalysts for exceptional hydrogen evolution performance

Abstract

The hydrogen evolution reaction (HER) plays a crucial role in realizing the ambitious objectives of renewable hydrogen (H₂) production and CO₂ neutrality. The efficacy of the HER process mainly relies on the electrocatalysts that are highly active, stable, and cost-effective, ensuring efficient and sustainable H₂ generation. In this study, binary copper–palladium (CuPd) alloy thin film catalysts directly grown on graphite sheets via aerosol-assisted chemical vapor deposition were employed for the HER in 0.5 M H₂SO₄. A unique array of tower-like microstructures were fabricated by varying the deposition time from 1 to 2 hours, demonstrating excellent HER activity by achieving high current densities of 100 and 1000 mA cm⁻² at low overpotentials of 64 and 137 mV, respectively. It also exhibited favorable Tafel kinetics (28 mV dec⁻¹), a high electrochemical surface area (3046 cm²), and reasonable stability over 24 hours, surpassing the benchmark Pt, Pd, and other reputed noble metal-based catalysts. The synergy between transition and noble metals (Cu–Pd) and the array of tower structure in the alloy has been shown to enhance conductivity and offer abundant active sites, resulting in its superior performance in the HER. Furthermore, density functional theory simulations indicated a decrease in the Gibbs free energy value for the binary CuPd alloy (−0.12 eV) compared to that of metallic Pd and Cu in the HER process, thereby validating the experimental observations. This study presents a straightforward deposition technique to design robust and efficient thin film electrocatalysts and optimize electrochemically active sites to achieve faster HER rates with low overpotential.