Synthesis of palladium-silver electrocatalyst by cyclic voltammetry on graphite substrate for electrochemical production of hydrogen in acid media

Abstract

Electrochemical production of hydrogen using high-efficiency catalysts is an effective way to achieve a clean and renewable energy source. Palladium as one of the best elements as a catalyst has a very high price. In the present study, the use of silver metal reduced the consumption of palladium and improved its efficiency. In this research, Pd-Ag coating was generated using the cyclic voltametric electrochemical deposition method in a deposition bath containing palladium and silver ions on the surface of graphite rods. Factors such as coating marking method, the concentration of two salts, number of cycles, and scanning speed were optimized. Various electrochemical tests were performed to measure the activity and catalytic stability of the samples in one-tenth of a molar sulfuric acid electrolyte. To study the surface characteristics of the coatings, field emission electron microscopy (FESEM) test equipped with X-ray energy diffraction (EDS) spectrometer and X-ray diffraction (XRD) tests were used. In the optimal case, the overvoltage in the current flux of -10 mA / cm2 is equal to -177.5 mV and its TOEFL slope is equal to (mV.dec-1) 120.9, which is one of the best catalytic activities. Compared to other coatings based on silver and palladium. The reasons for the high catalytic activity of the optimal sample include the synergy of silver and palladium atoms, the resulting nanocluster structure, and the high electrochemically active surface area. A very small change in the optimal potential of the electrode at a density of -100 mA / cm2 for 5 hours of electrolysis indicates the stability of the optimal electrode in working conditions and an acidic environment. The low-cost, single-step fabrication method without the use of any adhesives or binders and the very high catalyst activity and good stability of the optimal Pd-Ag sample make it possible to use this electrode commercially.

Keywords

• electrochemical precipitation
• electrocatalyst
• silver-palladium
• hydrogen production reaction