The potential of tantalum as an efficient electrocatalyst for green hydrogen production

Abstract

Worldwide, discovering a low-cost, highly active and durable electrocatalyst for green hydrogen production is an attractive research field for future renewable energy. Herein, we study the suitability of utilizing metallic Ta as promising electrocatalytic material for hydrogen creation from acidic solutions. The morphological structure and crystal lattice system, as well as the chemical composition and oxidation states of Ta are examined using scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy, respectively. Hydrogen evolution reaction (HER) on Ta is investigated using cathodic polarization and electrochemical impedance techniques as a function of electrolyte concentration, applied potential, and temperature. Various kinetic parameters distinguishing catalytic activity of the process on Ta including Tafel slope, exchange current density, cathodic transfer coefficient, and HER rates are determined. At −1500 mV cathodic potential in 0.5 M H2SO4 solution, the results confirm well that, to reach a similar HER rate of say 100 mA cm-2, the overpotential on Ta cathode is found equal -520 mV, which is lower than the value of -940 mV attained on the platinum cathode, indicating high electrocatalytic activity of the HER on Ta surface. The obtained results also demonstrated that, for the hydrogen production process the overpotential greatly diminishes and its current density significantly improves with increasing either the electrolyte concentration or its temperature. Additionally, Tafel slope analysis and impedance parameters establish that HER proceeds by the Volmer–Heyrovsky mechanism. The outcome of this study reveals that the valve metal Ta is a sustainable, efficient, and promising cathode for green hydrogen generation fuel from sulphuric acid electrolytes.