MXene Nanofibers as Highly Active Catalysts for Hydrogen Evolution Reaction

Nonprecious metal catalysts for hydrogen evolution reaction (HER) have recently received growing attention. Herein, we designed a highly active MXene nanofiber catalyst with a high specific surface area (SSA) via the hydrolyzation of bulk MAX ceramics, and a subsequent HF etching process. Compared with traditional MXene flakes, the MXene nanofibers delivered a much higher SSA and exposed more active sites in the cross section. As a result, the MXene nanofiber delivered an enhanced HER activity with a low overpotential of 169 mV at a current density of 10 mA cm^-2, a depressed Tafel slope of 97 mV dec^-1, and low electrochemical resistance. The improved SSA and exposed active sites are responsible for the enhanced activity. This work provides a novel synthesis method for MXene nanofibers, and MXene nanofibers are also promising for applications in batteries, supercapacitors, and catalytic fields.