Confined growth of MoSe2 nanosheets in N-doped carbon shell with hierarchical porous structure for efficient hydrogen evolution

Abstract

Construction of reasonable composite architecture to enhance the robustness, alleviate the aggregation, and simultaneously improve the intrinsic poor conductivity is the key to realizing the synthesis of highly efficient noble-metal-free MoSe₂-based electrocatalysts for the hydrogen evolution reaction (HER). Herein, space-confined MoSe₂ nanosheets grown in an N-doped carbon shell with a hierarchical porous structure (defined as MoSe₂/NDC) were designed and fabricated, which acquire improved conductivity and more exposed active sites for hydrogen atom adsorption, exhibiting excellent HER activity both in alkaline and acidic media with a small overpotential of 155/142 mV at a current density of 10 mA cm⁻², and a Tafel slope of 68/62 mV dec⁻¹, respectively. More importantly, thanks to the protection of the outermost N-doped carbon layer, the MoSe₂/NDC shows excellent durability, with almost no attenuation observed in the time-dependent current density curve at an applied constant overpotential of 155/142 mV up to 24 hours in alkaline or acidic media. The following density functional theory (DFT) calculation results reveal that the excellent HER activity of MoSe₂/NDC composites originates from the substantially reduced |ΔG_H*| of the intermediate adsorbed hydrogen. The strategy of in situ space-confined-growth combined with the design of a composite hierarchical porous structure provides an efficient solution to fabricate high-performance MoSe₂-based pH-universal electrocatalysts for hydrogen production.