Hydrogen Evolution Reaction on Hybrid Catalysts of Vertical MoS₂ Nanosheets and Hydrogenated Graphene

Abstract

Two-dimensional (2D) molybdenum sulfide (MoS 2 ) is an attractive noble-metal-free electrocatalyst for hydrogen evolution (HER) in acids. Tremendous effort has been made to engineer MoS 2 catalysts with either more active sites or higher conductivity to enhance their HER activity. However, little attention has been paid to synergistically structural and electronic modulations of MoS 2 . Herein, 2D hydrogenated graphene (HG) is introduced into MoS 2 ultrathin nanosheets for the construction of a highly efficient and stable catalyst for HER. Owing to synergistic modulations of both structural and electronic benefits to MoS 2 nanosheets via HG support, such a catalyst has improved conductivity, more accessible catalytic active sites, and moderate hydrogen adsorption energy. On the optimized MoS 2 /HG hybrid catalyst, HER occurs with an overpotential of 124 mV at 10 mA cm −2 , a Tafel slope of 41 mV dec −1 , and a stable durability for 24 h continuous operation at 30 mA cm −2 without observable fading. The high performance of the optimized MoS 2 /HG hybrid catalyst for HER was interpreted with density functional theory calculations. The simulation results reveal that the introduction of HG modulates the electronic structure of MoS 2 to increase the number of active sites and simultaneously optimizes the hydrogen adsorption energy at S-edge atoms, eventually promoting HER activity. This study thus provides a strategy to design and develop high-performance HER electrocatalysts by employing different 2D materials.

Pore Surface Engineering of Covalent Triazine Frameworks@MoS2 Electrocatalyst for the Hydrogen Evolution Reaction

“…[40] Bifunctional hollow rGO spher-es@MoS 2 catalyste xhibited aT afel slope of 105 mV dec À1 . [42] In addition, the exchange current density was used to investigate the mechanism of the surface active sites on the catalyst. [41] AT afel slope of 43 mV dec À1 for CTFs@MoS 2 -5 indicates the mechanism of HER follows the Volmer-Heyrovsky model,i nw hich the rate-determining step is:H ads + H 3 O + + e À !H 2 + H 2 O.…”

Modulating Schottky Barrier of MoS2 to Enhance Hydrogen Evolution Reaction Activity by Incorporating with Vertical Graphene Nanosheets Derived from Organic Liquid Waste

“…Amongst, the earth‐abundant and cost‐effective electrocatalyst like Molybdenum disulfide (MoS 2 ), exhibits prominent potential to circumvent the limitations of the currently used Pt‐group electrocatalyst with the disadvantages of scarcity and high cost . Since the first discovery of the contribution of catalyst‐electrolyte interface to HER activity, optimizing the active edge sites of MoS 2 via doping and edging has witnessed great progress ,. Nevertheless, the practical catalytic performance of various nanostructure MoS 2 is still inferior compared to Pt, which is mainly challenged by its intrinsic obstacles including low utilization of active sites, unstable mechanical stability and poor charge‐transfer efficiency .…”

“…The Figure d demonstrates a curled rim structure of VGNS, consisting of 3∼20 layers of graphene with the interlayer spacing of about 0.35 nm, which is in accordance with previous results of SEM images and Raman spectrum. Figure e reveals the crystalline structure of VGNS/MoS 2 by the selected area electron diffraction (SEAD) pattern, including diffraction spots (assigned to polycrystalline MoS 2 ) and the diffraction rings (assigned to graphene sheets with good crystalline) ,. X‐ray photoelectron spectroscopy is used to quantitatively evaluate the interfacial nature between VNGS and MoS 2 in terms of chemical composition and atom valence states .…”

Molybdenum‐Based Carbon Hybrid Materials to Enhance the Hydrogen Evolution Reaction

“…They developed a microwave-assisted synthesis approach [58] using an onhydrolytic sol-gel methodt op repare MoS 2 /RGO catalysts rapidlyf or HER from butyl mercaptan and MoCl 5 on graphene oxide (GO). Han et al [60] developedM oS 2 /HG hybrid catalyst from (NH 4 ) 2 MoS 4 with 2D HG obtained using am odified electrochemical exfoliation method. Liao et al [57a] developed 3D mesoporousg raphene foam (MGF)f rom GO and silica nanospheres.T he active catalystn anocomposite from MoS 2 was synthesized through ah ydrothermal route on an MGF with nanometre-scale pores using (NH 4 ) 2 MoS 4 .T he 3D MGF,w hich provided high electrical conductivity,l arges urface area (819 m 2 g À1 ), electrical conductivity and an aggregation-free structure, was synthesized through reduction of GO and etching SiO 2 of nanospheresi naGO/SiO 2 mixture.…”