2D bifunctional tungsten disulfide-embedded UiO-66 (WS2@UiO-66) as a highly active electrocatalyst for water splitting

Abstract

Effective water-splitting electrocatalysts provide great potential for the production of hydrogen as fuel in renewable and sustainable energy devices. Electrocatalysts become the bottleneck in the process of achieving easy and cost-effective water-splitting and require tremendous attention on the catalyst design. An economical, greatly stable, and effective electrocatalyst with low activation potential is usually required. In this study, we present a solvothermal method for the synthesis of a highly effective electrocatalyst, denoted as WS₂@UiO-66, to facilitate rapid and efficient water splitting. WS₂@UiO-66 forms a heterostructure, allowing for efficient overall water splitting. Open structures with many active sites are accessible to the reactants in this bifunctional design, which promotes mass diffusion and electron transport. In an alkaline solution, WS₂/UiO-66 exhibits exceptional HER and OER activity, requiring an HER overpotential of 121 mV and OER overpotential of 220 mV to yield a current density of 10 mA cm⁻². The best catalyst shows a smaller Tafel value of 272 mV dec⁻¹ and 140 mV dec⁻¹ for HER and OER, respectively. Furthermore, at a current density of 10 mA cm⁻², WS₂@UiO-66 can sustain HER/OER without a substantial loss for 24 hours. The outstanding bifunctional catalytic performance of WS₂@UiO-66 can significantly accelerate its utilization in water splitting. This research may pave the way for the development of new methods for cost-effective energy conversion and storage catalysts.