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 3 C 2 T x MXene layers was employed by uniformly growing embedded WS 2 two-dimensional (2D) nanopetal-like sheets through a facile solvothermal method. We exploited the interactions between WS 2 nanopetals and Ti 3 C 2 T x nanolayers to enhance HER performance. A much safer method was adopted to synthesize the base material, Ti 3 C 2 T x MXene, by etching its MAX phase through mild in situ HF formation. Consequently, WS 2 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 2 and Ti 3 C 2 T x 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 2 into MXene, the 5% WS 2 -Ti 3 C 2 T x 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 -2 in a 1 M KOH electrolyte and a remarkable Tafel slope of 46.7 mV·dec -1 . The intercalation of 2D WS 2 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 2 and Ti 3 C 2 T x MXene realign the active centers for HER, thereby reducing the overpotential barrier.