Controllable Sandwiching of Reduced Graphene Oxide in Hierarchical Defect‐Rich MoS₂ Ultrathin Nanosheets with Expanded Interlayer Spacing for Electrocatalytic Hydrogen Evolution Reaction

Abstract

The successful designing of low‐cost and highly active electrocatalytic materials from earth‐abundant elements are favorable for the large scale production of hydrogen from water splitting. Herein, the controllable sandwiching of reduced graphene oxide (RGO) in hierarchical defect‐rich MoS2 ultrathin nanosheets (MoSGMoS) with vertical alignment and expanded interlayer spacing is synthesized by hydrothermal method. The MoSGMoS product exhibits outstanding electrocatalytic activity for hydrogen evolution reaction (HER) with an onset overpotential of 24.3 mV, low overpotentials of 72 mV at 10 mA cm−2 and 384 mV at 1300 mA cm−2, a small Tafel slope of 44.7 mV decade−1, large exchange current density of 0.67 mA cm−2, and high durability in H2SO4 solution. The HER performance of the MoSGMoS catalyst is much better than most of the reported MoS2‐based catalysts, especially in terms of onset overpotential and cathodic current density. The synergistic effect between defect‐rich MoS2 ultrathin nanosheets with hierarchical structure, vertical alignment and expanded interlayer spacing, and conductive RGO is responsible for the outstanding HER activity. This method may open a new way to grow hierarchical MoS2 nanosheets on carbonaceous materials for enhanced hydrogen production from water splitting.

Nickel@Nitrogen‐Doped Carbon@MoS2 Nanosheets: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

“…As shown in Figure f and also in Figure S3 (Supporting Information), the layer number of MoS 2 nanosheets is in the range of 2–14 layers; the interlayer spacing of the MoS 2 nanosheets is about 0.75–0.95 nm, which is much larger than that of bulk MoS 2 (0.62 nm) . Furthermore, the defects in MoS 2 nanosheets can be observed in the HRTEM images (Figure S3, Supporting Information), which can also contribute to the enhancement of HER performance . The dark‐field TEM image of Ni@NC@MoS 2 (Figure g) and the corresponding elemental mapping images of Mo, S, Ni, C, and N (Figure h–l) further confirm the composition and the core–shell structure of the product.…”

“…The weakened pyridinic N peak in XPS spectrum of Ni@NC@MoS 2 compared to pure Ni@NC suggests the presence of some interaction between the N atoms and MoS 2 (Figure S4f,g). Due to the intrinsic layered crystal structure of MoS 2 , MoS 2 nanosheets grew mostly vertically on Ni@NC substrate to form Ni@NC@MoS 2 hierarchical sub‐microspheres …”

“…has been reported with improved HER catalytic activities. Recently, we reported the controllable sandwiching of reduced graphene oxide in hierarchical defect‐rich MoS 2 ultrathin nanosheets with vertical alignment and expanded interlayer spacing . The obtained composite exhibits excellent electrocatalytic activity for HER.…”

MoS2 as a Co-Catalyst for Photocatalytic Hydrogen Production: A Mini Review

“…Hydrothermal and solvothermal methods are the most interesting for the preparation of MoS 2 nanosheets [ 67 , 68 ]. In these methods, the Mo source is commonly a molybdate, such as Na 2 MoO 4 or (NH 4 ) 6 Mo 7 O 24 , and the S source is thiourea and thioacetamide and L-cysteine [ 69 , 70 , 71 , 72 , 73 ]. The molybdate reacts with the S or S compound in a stainless steel autoclave.…”

Spectroscopic Analyses of Changes in Photocatalytic and Catalytic Activities of Mn- and Ni-Ion Doped and Base-Treated Reduced Graphene Oxide

“…However, efforts are being made to further improve the catalytic activity of rGO. In particular, it has been reported that rGO doped with TM ions shows improved catalytic activity because the dopant ions increase the number of defect structures present on rGO [28][29][30][31][32].…”