Electrocatalytic activity of tungsten carbide hybrids with two different MOFs for water splitting: a comparative analysis

Abstract

Conventional energy resources are diminishing, and environmental pollution is constantly increasing because of the excessive use of fossil fuels to sustain the ever-increasing population and industrialization. This has raised concerns regarding a sustainable future. In the pursuit of addressing sustainability in industrial processes and energy systems, the production of green hydrogen is considered a promising and crucial solution to meet the growing energy demands. Water-splitting is one of the most effective technologies for producing clean and carbon-neutral hydrogen. Water-splitting is a scientifically emerging application, but it is commercially limited due to its economic non-viability. The sluggish kinetics and the high overpotential needed for the water-splitting reactions (HER and OER) have encouraged the scientific community to design electrocatalysts that address the concerns of low activity, efficiency and stability. Designing a hybrid catalyst using metal-organic frameworks (MOFs) with transition metal carbides can be a suitable approach to address the deficiencies of conventional water-splitting catalysts. In this study, we have designed and fabricated an electrocatalyst of tungsten carbide (WC) with two different MOFs (Zr-based and Fe-based) and explored their electrocatalytic activity for hydrogen generation in an alkaline medium. It should be noted that hybrids of tungsten carbide with a zirconia MOF (UiO-66) showed better electrocatalytic activity with low overpotentials of 104 mV (HER) and 152 mV (OER) at a current density of 10 mA cm−2. This superior activity of WC with the Zr-MOF in comparison to the Fe-MOF is due to the synergistic effect of Zr present in UiO-66 grown on the WC matrix. Moreover, UiO-66 provides a larger electrocatalytic active surface area, so available active sites are more in UiO-66 as compared to the Fe-MOF. These findings set the stage for the systematic development and production of bi-functional hybrid catalysts with the potential to be utilized in water-splitting processes.