Synergistic Catalyst Design for Enhanced Electrochemical Hydrogen Evolution: Fe₂O₃/MoS₂/Ti₃C₂T_<i>x</i> MXene Ternary Composite

Abstract

Developing a cost-effective and earth-abundant electrocatalyst to produce green hydrogen is vital toward sustainable energy with a net-zero carbon emission. In this regard, abundantly available nanostructured transition metals with a tunable structure, high surface area, and high conductivity are considered to be suitable cathode materials for water splitting. Herein, we design a 3D/2D Fe2O3/MoS2/Ti3C2Tx MXene ternary composite through hydrothermal synthesis for electrochemical hydrogen evolution. The 3D/2D composite of Fe2O3 nanoparticles with MoS2 nanosheets showed exceptional electrocatalytic activity with an overpotential and a Tafel slope of 194.1 mV and 102 mV/dec, respectively, which outperforms pristine Fe2O3 nanoparticles and MoS2 nanosheets by a great margin of over 50 mV. To further enhance the electrical conductivity, exfoliated Ti3C2Tx MXene is introduced to form a ternary composite, and it is found that this composite electrocatalyst shows an impressive overpotential of 123 mV at a current density of 10 mA/cm2 in an acidic medium, with high durability over 12 h for hydrogen evolution. The smaller charge-transfer resistance (88.2 Ω) and larger double-layer capacitance (12 mF/cm2) values of the ternary composite with a low Tafel slope of 71 mV/dec indicate the role of enhanced interfacial charge transfer and specific surface area inducing enhanced HER activity.