Thermochemical synthesis of Mo nano/microspheres: growth kinetics, electrocatalytic hydrogen evolution, and DFT insights†

Abstract

This study presents an efficient low-temperature process for synthesizing Mo nano- and microspheres for various applications. The synthesis process involves the preparation of a MoO₃ + kZn mixture with an excess of zinc (Zn > 3) and processing to temperatures between 500 and 850 °C in an argon atmosphere. The growth kinetics of Mo particles are determined by analyzing the relationship between sphere diameter and processing time. Molybdenum nano- and microspheres are applied as electrocatalysts for the hydrogen evolution reaction (HER) and high electrocatalytic activity, including low overpotential (170–206 mV) and Tafel slope (40–50 mV dec⁻¹) are recorded in 0.5 M H₂SO₄ electrolyte. DFT calculation provides adsorption Gibbs free energy for (001), (110), and (211) surfaces of Mo and charge density plots on pure Mo and Mo–O surfaces. As for vacuum-distilled Zn, its microstructure is also studied for its reuse and to assess its potential for additive manufacturing.