Engineering Sulfur Defects, Atomic Thickness, and Porous Structures into Cobalt Sulfide Nanosheets for Efficient Electrocatalytic Alkaline Hydrogen Evolution

The development of nonprecious metal-based electrocatalysts with high mass activity and efficient atom utilization for alkali hydrogen evolution reaction (HER) is of great importance for the preparation of hydrogen resource. The combination of ultrathin and porous structure, especially with the assistance of vacancy, is expected to be beneficial for achievement of high mass activity, but the development of a facile, robust, and generalized strategy to engineer ultrathin, porous, and vacancy-rich structure into nonlayer structured transition metal-based electrocatalysts is highly challenging. Here, we propose a plasma-induced dry exfoliation method to prepare nonlayer structured Co3S4 ultrathin porous nanosheets with abundant sulfur vacancies (Co3S4 PNSvac), which show an onset overpotential of only 18 mV and an extremely large mass activity of 1056.6 A g–1 at an overpotential of 200 mV. Experimental results and theoretical calculations confirm that the efficient alkaline HER performance could be attributed to the abundant active sites, good intrinsic activity, and accelerated electron/mass transfer. Additionally, the plasma-assisted conversion method can also be extended to fabricate CoSe2 and NiSe2 ultrathin porous nanosheets with selenium vacancies.