Hollow Sandwiched Structure of Ni-Modified MoS₂ Wrapped into Symmetrical N-Doped Carbon toward a Superior Hydrogen Evolution Electrocatalyst

Abstract

As a promising cost-effective electrocatalyst for hydrogen evolution reaction (HER), molybdenum disulfide (MoS 2 ) has been drawing more attention. However, the desired performances are restricted by the poor conductivity and inadequate active sites. To address these obstructions, herein, we design and fabricate an intelligent sandwiched nanostructure of hierarchical hollow nanospheres, which are assembled by Nimodified MoS 2 nanosheets encapsulated into N-doped carbon layers (NC@MoS 2 /Ni-NC HNSs). The hybrid catalyst exhibits significantly increased electrical conductivity and active area, thereby maximally exposing the rich active sites. Additionally, the sandwiched hierarchy is favorable for preventing the agglomeration of the nanosheets to ensure the excellent stability. Consequently, such NC@MoS 2 /Ni-NC HNSs show brilliant HER performance with a delightful onset overpotential of ∼16.8 mV and a low overpotential of 82.1 mV to achieve a current density of 10 mA cm −2 in alkaline solution, together with the prominent long-term stability and durability for over 35 h. Theoretical studies underline that metallic Ni doping can not only tune the electronic structures and optimize the appropriate free energy of H* adsorption (ΔG H* ), but also release inert basal plane to activated sites, leading to the boosted HER performance.

Interfacial Mo–N–C Bond Endowed Hydrogen Evolution Reaction on MoSe2@N-Doped Carbon Hollow Nanoflowers

“…The optimal structural models including NC, MoSe 2 , MoSe 2 @NC, and MoSe 2 @NC decorated with Mo–N–C bonds (named as B-MoSe 2 @NC) are shown in Figures a,b and S28. The Gibbs free energy for hydrogen adsorption (termed as Δ G H* , where * denotes the adsorption sites) is usually regarded as a major index for excellent HER activity. , The catalyst with a nearly zero |Δ G H* | implies favorable reaction kinetics and improved HER activity. As presented in Figure c, the |Δ G H* | value for MoSe 2 @NC is only 0.97 eV, outperforming that for bare MoSe 2 (1.33 eV) and NC (3.74 eV).…”

Recent advances in solution assisted synthesis of transition metal chalcogenides for photo-electrocatalytic hydrogen evolution

“…To obtain hollow MoS 2 cubes, MnS@MoS 2 was treated with 1.0 M HCl aqueous solution for 24 h at room temperature. Other kinds of templates, such as silica gel, 121,122 and Ni-foam, 123 have been utilized for the shape-controlled synthesis of MoS 2 .…”

Low-dimensional transition metal sulfide-based electrocatalysts for water electrolysis: overview and perspectives

“…6 The compounds of transition metal elements are popular electrocatalysts, which are regarded as the materials holding most promise for the future, including sulfides, phosphides, selenides, nitrides, borides, carbides, etc . 7,8 Among them, transition metal sulfides (TMS), such as MoS 2 , 9 WS 2 , 10 CoS 2 , 11 CuS, 12 FeS 2 , 13 NiS 2 , 14 etc. , are an intriguing family of materials with large application potential in a variety of scientific fields ranging from electronics to electrocatalysis due to their high catalytic activity.…”