Controllable Edge Exposure of MoS2 for Efficient Hydrogen Evolution with High Current Density

MoS2-based electrocatalysts are promising cost-effective replacements for Pt-based catalysts for hydrogen evolution by water splitting, yet achieving high current density at low overpotential remains a challenge. Herein, a binder-free electrode of MoS2/CNF (carbon nanofiber) is prepared by electrospinning and subsequent thermal treatment. The growth of MoS2 nanoplates contained within or protruding out from the CNF can be controlled by adding urea or ammonium bicarbonate to the electrospinning precursors, due to the cross-linking effects of urea and the increased porosity caused by pyrolysis of ammonium bicarbonate allowing growth through pores in the CNF. By virtue of the abundant exposed edges in this microstructure and strong bonding between the catalyst and the conductive carbon network, the composite material exhibits ultrahigh electrocatalytic hydrogen evolution activity in acidic solutions, with current densities of 500 and 1000 mA/cm2 at overpotentials of 380 and 450 mV, respectively, exceeding the performance of many reported MoS2-based catalysts and even commercial Pt/C catalysts. Thus, MoS2/CNF membranes show potential as efficient and flexible binder-free electrodes for electrocatalytic hydrogen production.