Ultrathin MXene nanosheets for electrocatalytic hydrogen evolution under alkaline condition

MXene (Ti₃C₂T_x) was prepared by etching MAX (Ti₃AlC₂) raw material and then ultrathin MXene nanosheets (MXene-NS, namely Ti₃C₂T_x-NS) was fabricated by using exfoliating method. The morphology, structure and elemental composition of the MXene-NS were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic hydrogen evolution reaction (HER) properties of MAX, MXene and MXene-NS were compared by electrochemical tests. The results revealed that compared with MAX and MXene, in 1 mol/L KOH, MXene-NS exhibited the lowest overpotential (190 mV@ −10 mA/cm²), the smallest Tafel slope (168 mV/dec), the smallest charge transfer resistance and the largest electrochemical active surface area. In addition, MXene-NS displayed a good potential response vs. current density. Furthermore, after long-term durability test, the polarization curve of MXene-NS was not notably decayed, which demonstrated the excellent stability for hydrogen evolution. All these results indicated that the exfoliation of MXene could effectively improve its electrocatalytic performance and the as-exfoliated MXene-NS was an excellent alternative for replacing the noble metal catalysts.