In Situ Growth of Interfacially Nanoengineered 2D–2D WS2/Ti3C2Tx 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 Ti₃C₂T_x MXene layers was employed by uniformly growing embedded WS₂ two-dimensional (2D) nanopetal-like sheets through a facile solvothermal method. We exploited the interactions between WS₂ nanopetals and Ti₃C₂T_x nanolayers to enhance HER performance. A much safer method was adopted to synthesize the base material, Ti₃C₂T_x MXene, by etching its MAX phase through mild in situ HF formation. Consequently, WS₂ 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 WS₂ and Ti₃C₂T_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 WS₂ into MXene, the 5% WS₂–Ti₃C₂T_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 WS₂ 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-WS₂ and Ti₃C₂T_x MXene realign the active centers for HER, thereby reducing the overpotential barrier.