In Situ Growth of Interfacially Nanoengineered 2D-2D WS 2 /Ti 3 C 2 T x MXene for the Enhanced Performance of Hydrogen Evolution Reactions

In line with current research goals involving water splitting for hydrogen production, this work aims to develop a noble-metal-free electrocatalyst for a superior hydrogen evolution reaction (HER). A single-step interfacial activation of Ti C T MXene layers was employed by uniformly growing embedded WS two-dimensional (2D) nanopetal-like sheets through a facile solvothermal method. We exploited the interactions between WS nanopetals and Ti C T nanolayers to enhance HER performance. A much safer method was adopted to synthesize the base material, Ti C T MXene, by etching its MAX phase through mild in situ HF formation. Consequently, WS nanopetals were grown between the MXene layers and on edges in a one-step solvothermal method, resulting in a 2D-2D nanocomposite with enhanced interactions between WS and Ti C T MXene. The resulting 2D-2D nanocomposite was thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses before being utilized as working electrodes for HER application. Among various loadings of WS into MXene, the 5% WS -Ti C T MXene sample exhibited the best activity toward HER, with a low overpotential value of 66.0 mV at a current density of -10 mA cm in a 1 M KOH electrolyte and a remarkable Tafel slope of 46.7 mV·dec . The intercalation of 2D WS nanopetals enhances active sites for hydrogen adsorption, promotes charge transfer, and helps attain an electrochemical stability of 50 h, boosting HER reduction potential. Furthermore, theoretical calculations confirmed that 2D-2D interactions between 1T/2H-WS and Ti C T MXene realign the active centers for HER, thereby reducing the overpotential barrier.