Efficient utilization of sulfur atom in MoS₂-based electrocatalysts on the basal plane is highly desirable and expectable to optimize the electrocatalytic performance for hydrogen evolution reaction (HER). Herein, removing atoms on the basal plane of layered MoS₂ by Li-ion intercalation leading to extraordinarily enhanced electrocatalytic performance is newly reported, which provides a novel way to active the basal planes of layered transition metal sulfides towards hydrogen evolution. It is found that the desulfurization of layered MoS₂ can bring atomic vacancies on the basal plane, which is confirmed to be active sites towards hydrogen evolution experimentally and theoretically. The first-principle calculations reveal that the desulfurization induced atomic vacancies not only reduce the free energy of hydrogen adsorption (ΔG_H*), but also accelerate the electron transfer on the basal plane. Besides, the phase transformation from 2H to 1T during the electrochemical lithium-ion intercalation could reach higher electronic conductivity, thus further optimize the HER kinetics through phase engineering. For these reasons, the desulfurized MoS₂ displays improved HER activity with lowered overpotential of 200 mV to obtain 10 mA cm⁻², high stability, decreased Tafel slope of 65 mV dec⁻¹ and enhanced TOF of 0.093H₂ s⁻¹ at overpotential of 250 mV, which are much better than that of the pristine MoS₂ and other optimized MoS₂-based catalysts.

在基面上的基于MoS ₂的电催化剂中高效利用硫原子是非常理想的，并且有望优化氢析出反应（HER）的电催化性能。本文中，新报道了通过Li-离子嵌入去除层状MoS ₂的基面上的原子，从而导致电催化性能大大提高的现象，这为使层状过渡金属硫化物的基面朝着氢的活化提供了一种新途径。发现层状MoS ₂的脱硫可以在基面上带来原子空位，这在实验和理论上被证实是氢释放的活性位点。第一性原理计算表明，脱硫引起的原子空位不仅降低了氢吸附的自由能（ΔGH _*），而且还加速了基面​​上的电子转移。此外，电化学锂离子嵌入过程中从2H到1T的相变可以达到更高的电子电导率，从而通过相工程进一步优化了HER动力学。由于这些原因，脱硫的MoS ₂显示出更高的HER活性，降低了200 mV的过电势以获得10 mA cm ^-2，高稳定性，降低了65 mV dec ^-1的Tafel斜率在250 mV的超电势下，TOF为0.093H ₂ s ^-1，这比原始的MoS ₂和其他优化的基于MoS ₂的催化剂要好得多。