Vacancy defects caused by doping are beneficial to optimizing the regional electronic structure and increasing exposed active sites, and it is vital to improve the efficiency of hydrogen evolution reaction (HER). Herein, we constructed the Fe-doped molybdenum sulfide encapsulated with N-doped carbon (FeMoSN@ NC), which with ultrathin edge-curled layer structure. Fe-doping realized with Prussian blue nanocages as the precursors, which plays a crucial role in the formation of ultrathin layer assembled microspheres. Experimental tests and theoretical calculations show that the Fe-doping can not only expand the interlayer of MoS 2 (∼11 Å) to obtain ultrathin layers but also embed into the in-plane location of MoS 2 to form high-density doping and vacancy defects. The regulation of regional active sites caused by Fe-doping can enhance the intrinsic catalytic activity of catalyst, including more active sites for HER, appropriate Gibbs free energy of hydrogen adsorption (−0.11 eV of Fe1 Mo -V Mo,S ), and low resistance for carrier transfer (9 Ω). FeMoSN@NC as the HER electrocatalyst exhibits efficient activity with a Tafel slope of 67 mV dec −1 and an overpotential of 150 mV at the current density of −100 mA mg −1 . The above insights provide new transition metal doping strategy for efficient molybdenum sulfide electrocatalysts with optimized active sites and increased electrochemical active area.

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VS 2 nanomaterials with special morphology, exposed edges, defects have studied as an active and inexpensive electrocatalyst for hydrogen evolution reaction (HER). Here, we reported the fabrication of multilayer Waffle structured VS 2 featuring rich hole defects (VS 2 MLW). This structure shows excellent kinetic metrics for electrocatalytic HER, exhibiting a overpotential of 82 mV at the current density of −10 mA cm −2 , a Tafel slope of 61 mV dec −1 , and a long-term stability without any current fading. Its HER performance is much better than that of other V-based catalysts, and even comparable to that of commercial Pt/C. Through experimental and theoretical calculation, the outstanding electrocatalytic activity of the VS 2 MLW is attributed to its special morphology and electronic structure. The hole defects in this structure provide larger electrochemical active area and more active sites for HER, more importantly, hole defects change the electron structure of catalyst and reduce the free energy of hydrogen adsorption, the optimized free energy consequently leading to the improved inherent catalytic activity of VS 2 MLW. This work provides a new concept to design efficient HER catalyst by specific surface area and defect engineering.

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