Itaconic acid modified carboxylic-acid functionalized (002) faceted monoclinic WO₃ nanorods for electrochemical hydrogen evolution reaction

Design of strategies to modify the hydrogen evolution activity of electrocatalysts is vital for the commercial implementation of hydrogen production. Herein, we explore the surface modification of monoclinic WO₃ using itaconic acid (ITA) ligand via a facile hydrothermal synthesis route. Comprehensive XRD, HRTEM, FTIR, and Raman analyses confirmed the formation of (002) oriented monoclinic WO₃ and the successful incorporation of ITA coating on the WO₃ samples. The FESEM images illustrated the randomly coated ITA particles on the smooth nanorods of m-WO₃ nanorods. The ITA-coated m-WO₃ demonstrated an overpotential of 267 mV at 10 mA/cm² current density and exhibited a lower Tafel slope and charge transfer resistance in an acidic electrolyte medium. The carboxylic groups of itaconic acid promote proton transfer, which, along with the highly reactive (002) dominant facets of WO₃, synergistically enhanced the HER activity. The (002) oriented WO₃ sample with the highest mass loading of itaconic acid (0.3 M) resulted in a tenfold increase in surface area, thereby enhancing the accessible active sites. The enhanced porosity and proton transfer properties of the itaconic acid on integration with WO₃ improved their potential as an HER electrocatalyst.