MoS2 For Hydrogen Evolution Reaction Research Articles

Construction of a p-p heterojunction Co3O4/MoS2 electrocatalyst for boosting hydrogen evolution reaction

Building p-p heterojunctions with Fermi level difference, due to the motion of energy levels, band bending, and internal electric field generation, can effectively improve the electronic structure of the interface, enrich the active sites of heterojunctions, and promote the adsorption of reaction intermediates, which is an effective approach to constructing high-performance electrocatalysts. In this study, a Co3O4/MoS2 p-p heterojunction catalyst with nano-particle/nano-flower structure was designed, inducing charge transfer from Co3O4 to MoS2, thereby increasing the negative charge of MoS2, improving *H adsorption through electrostatic interaction, enhancing electrocatalytic kinetics, and reducing reaction overpotential. The catalytic performance of MoS2 for hydrogen evolution reaction was effectively enhanced. In 1 M KOH solution, the current density was 10 mA cm−2, and the overpotential was 156 mV, with good stability after 40 h of operation. This work provides a new direction for the design of p-p heterojunction electrocatalysts and offers more choices for promoting the development of high-performance non-noble metal catalysts.

Electron induced construction of heterogeneous MoS2 for highly efficient hydrogen evolution reaction

MoS2 as one earth-abundant transition metals dichalcogenides has become a promising electrocatalyst for hydrogen evolution reaction (HER). The synthesis of heterojunction structure via phase transformation and doping engineering could integrate synergistic effects to improve the electrocatalytic activity. Herein, we propose to prepare the 1T/2H heterostructure of Ni-doped MoS2 nanosheets through the hydrothermal and doping methods. The extra electrons form donor Ni atoms can induce the phase transition of MoS2 (from 2H phase to 1T phase) via changing the configuration of the orbitals. Thus, the heterojunction of Ni-MoS2@CC-2 shows excellent catalytic activity with an overpotential of 112 mV at 10 mA cm−1 and a small Tafel slope of 87 mV dec−1. This work provides a new strategy for optimizing the catalytic activity of MoS2 for HER.

Electrocatalysts based on MoS2 and WS2 for hydrogen evolution reaction: An overview

AbstractRecently, hydrogen energy has been significantly investigated by numerous technologies. To date, noble platinum group metals have often been employed to fabricate working electrodes for hydrogen evolution reaction (HER). Therefore, the demand of highly active HER catalysts based on effective and lower‐cost materials is becoming more and more critical. Transition metal dichalcogenide (TMD) materials could be one of the most suitable materials for these requirements because they possess numerous unique mechanical, electronic, and chemical characteristics that are greatly beneficial for HER processes. Among many TMD materials, tungsten disulfide (WS2) and molybdenum disulfide (MoS2) are the most well‐known TMD materials which have been intensively studied for different applications, including HER, batteries, and supercapacitors. In this review, we tried to cover the HER mechanism of catalysts and their parameters. Besides that, the structures, properties, preparation, and HER performance of catalyst materials based on WS2 and MoS2 are comprehensively discussed. After that, the challenges and future trends of catalysts based on WS2 and MoS2 for HER are also considered.

Catalysts for the hydrogen evolution reaction in alkaline medium: Configuring a cooperative mechanism at the Ag-Ag2S-MoS2 interface

Designing electrocatalysts for HER in alkaline conditions to overcome the sluggish kinetics associated with the additional water dissociation step is a recognized challenge in promoting the hydrogen economy. To this end, delicately tuning the atomic-scale structure and surface composition of nanoparticles is a common strategy and, specifically, making use of hybrid structures, can produce synergistic effects that lead to highly active catalysts. Here, we present a core-shell catalyst of Ag@MoS2 that shows promising results towards the hydrogen evolution reaction (HER) in both 0.5 M H2SO4 and 0.5 M KOH. In this hybrid structure, the MoS2 shell is strained and defective, and charge transfer occurs between the conductive core and the shell, contributing to the electrocatalytic activity. The shelling process results in a large fraction of Ag2S in the cores, and adjusting the relative fractions of Ag, Ag2S, and MoS2 leads to improved catalytic activity and fast charge-transfer kinetics. We suggest that the enhancement of alkaline HER is associated with a cooperative effect of the interfaces, where the Ag(I) sites in Ag2S drive the water dissociation step, and the formed hydrogen subsequently recombines on the defective MoS2 shell. This study demonstrates the benefits of hybrid structures as functional nanomaterials and provides a scheme to activate MoS2 for HER in alkaline conditions.

Intercalation of coordination polymer to regulate interlayer of 2D layered MoS2 for hydrogen evolution reaction

Activity and stability are the kernels of MoS2-based catalysts for hydrogen evolution reactions (HER). Here an intercalation-exfoliation nanocomposite (N–MoS2/AOCF) was designed and successfully synthesized through a facile polymer-solution intercalation method, and the molecular chains of amidoximated polyacrylonitrile (AOCF) with coordinating ability was intercalated into the preintercalated molybdenum disulfide (N–MoS2) nanosheets. The structure characterization demonstrated that N–MoS2 dispersed randomly with a small size and curly lamellar structure. Besides, the interlayer spacing enlarged significantly in the AOCF matrix. Furthermore, N–MoS2 nanosheets are tightly combined with AOCF via the coordination bonds between –OH and –NH2 of AOCF; therefore, the diverse active sites and good stability of N–MoS2/AOCF were attributable to the intense bonding effect, inducing desirable HER performance in acidic medium. Notably, the obtained electrocatalyst exhibited a low overpotential (176 mV at a current density of 10 mA/cm2), a small Tafel slope (51.08 mV/dec), and a large electric double-layer capacitance (39.98 mF/cm2).

B- and N-doped carbon coupled with different morphologies of MoS2 for hydrogen evolution reaction

B- and N-doped carbon coupled with different morphologies of MoS2 for hydrogen evolution reaction

Monolayer 1T and 1T' MoSO as Promising Electrocatalyst for Hydrogen Evolution based on First Principle Calculations.

Molybdenum disulfide (MoS2 ) has been regarded as one of the most promising candidates for replacing Pt group noble metals as an efficient electrocatalyst to enhance the hydrogen evolution reaction (HER) in consideration of its relatively high earth abundance. Recent studies show that the catalytic efficiency of MoS2 for HER can be promoted by the presence of 1T-phase MoS2 . It is hard to precisely control the formation of 1T-MoS2 , however, due to its metastability relative to 2H-MoS2 . Elevating the stability of 1T phase allotrope is therefore of great importance and could be realized by replacing divalent S with monovalent elements or groups according to crystal field theory, which has been demonstrated through our first-principles density functional theory (DFT) calculation results. Differential Gibbs free energy analysis for hydrogen adsorption (ΔGH* ) suggest that 1T and 1T' MoSO (O doped MoS2 ) might be taken as potential candidate catalysts for HER process with better performance than 1T and 1T' MoS2 . We also propose a probable approach to synthesize 1T and 1T' MoSO under oxidation circumstance environment of graphene oxide.

Two-dimensional MOS2 for hydrogen evolution reaction catalysis: The electronic structure regulation

Molybdenum disulfide (MoS2) has been recognized as one of the most promising candidates to replace precious Pt for hydrogen evolution reaction (HER) catalysis, due to the natural abundance, low cost, tunable electronic properties, and excellent chemical stability. Although notable processes have been achieved in the past decades, their performance is still far less than that of Pt. Searching effective strategies to boosting their HER performance is still the primary goal. In this review, the recent process of the electronic regulation of MoS2 for HER is summarized, including band structure engineering, electronic state modulation, orbital orientation regulation, interface engineering. Last, the key challenges and opportunities in the development of MoS2-based materials for electrochemical HER are also discussed.

Defects Enhance the Electrocatalytic Hydrogen Evolution Properties of MoS2 -based Materials.

MoS2 have recently emerged as alternatives to noble metals as electrocatalysts for the hydrogen evolution reaction (HER) owing to their abundance and low cost. Considering the shortcomings of MoS2 , including insufficient active sites, inert basal plane, and poor conductivity, the electrocatalytic hydrogen evolution properties of MoS2 can be improved in three ways: activating the inert basal plane to improve intrinsic activity, increasing active edge sites, and improving the conductivity. Defects can adjust the surface electronic structure of the crystal to bring the hydrogen adsorption free energy closer to zero. Therefore, current research has mainly used S-vacancies to activate the inert basal surface of MoS2 ; used edge defects to increase the number of active sites; and used defective conductive carbon supports to improve the conductivity of MoS2 -based catalysts. This review introduces researches on improving the performance of MoS2 for HER by considering the purpose, characterization, and preparation of defects.

Wettability transition of Ni3B4-doped MoS2 for hydrogen evolution reaction by magnetron sputtering

The synthesis of non-noble electrocatalysts for hydrogen evolution reaction (HER) is a critical challenge for practical hydrogen production applications. Molybdenum sulfide materials have been proven to be an ideal catalyst for HER due to the edge activity was close to platinum. Herein, we report a novel and facile method for Ni3B4-doped MoS2 nanosheet directly deposited on Ni foam through co-sputtering. Benefiting from the transition of wettability from hydrophobic to hydrophilic and the existence of defects, the MoS2 + Ni3B4-10 W@NF exhibited outstanding electrocatalytic performance compare to pure-MoS2@NF in alkaline conditions. The results revel that the mixture of Ni3B4 degrees brings the wettability transition, which promote the contact between electrode and electrolyte, and the mixture of Ni3B4 degrees had an optimum condition. What’s more during the deposition process the bombardment and etching of ion induced defects, which expose more active sites.

CuS@defect-rich MoS2 core-shell structure for enhanced hydrogen evolution

The catalytic activity of MoS2 for hydrogen evolution reaction (HER) is closely-related to its active edge sites and electrical conductivity. In this work, a novel strategy to enhance HER by introducing defects into interface to take advantage of synergistic effect between them was reported. Specifically, in the first step, molybdenum disulfide (MoS2) with additional active edge sites was prepared through defect engineering, and then copper sulphide(CuS)@defect-rich MoS2 core-shell structure with better electron transport capability was constructed, thus achieving high-efficiency HER by synergistic effect. Benefiting from the additional active edge sites of the defect-rich MoS2 and the improved charge transport facilitated by the intimate interface, CuS@defect-rich MoS2 could afford a current density of 10 mA·cm−2 at a low overpotential of 135 mV and a Tafel slope of 50 mV·dec−1, as well as relatively long-term stability.

A feasible and environmentally friendly method to simultaneously synthesize MoS2 quantum dots and pore-rich monolayer MoS2 for hydrogen evolution reaction

MoS2 has been one of a widely researched hydrogen evolution reaction (HER) catalyst materials in recent years. However, the basal plane of MoS2 is considered to be inactive to hinder its further development. Herein, a new mass-scalable and facile intercalation method for the fabrication of multiple products, including pore-rich monolayer MoS2 (PR MoS2) and MoS2 quantum dots (MoS2 QDs), has been developed via the gas phase etching of bulk MoS2 in an acetone vapor atmosphere. The obtained monolayer MoS2 QDs with a narrow lateral size distribution (average size: 2.5 nm) present excitation-independent photoluminescence emission. Furthermore, the PR MoS2 shows a significantly enhanced HER electrocatalytic activity and good stability in 0.5 M H2SO4 solution with a small overpotential of 241 mV at a current density of 10 mA cm−2. These results demonstrate that the as-prepared PR MoS2 is very promising for the application in HER.

Building MoS2/S-doped g-C3N4 layered heterojunction electrocatalysts for efficient hydrogen evolution reaction

Developing the stable and efficient hydrogen evolution reaction (HER) electrocatalyst is greatly desirable for the production of hydrogen as a clean energy resource. Herein, we report a simple and effective approach to fabricate MoS2/S-doped g-C3N4 layered heterojunction electrocatalysts, which can adjust the electron structure, enhance the charge transfer rate and expose more active sites of MoS2 for HER. The optimized MoS2-C3N4-60 sample shows a small onset overpotential as low as 115 mV, a low overpotential of 173 mV to achieve current density of 10 mA/cm2, a low Tafel slope of 53 mV decade−1, and a high turnover frequency of 0.16 H2 s−1 per active site at η = 150 mV. This finding proposes a new strategy to fabricate 2D layered heterojunction for enhancing HER performance by rationally coupling two similar layered materials.

Rare-Earth Elements Modified 1T Phase Mos2 Synergy with Defects for Enhanced Hydrogen Evolution

Earth-abundant MoS2 has drawn continuous attentions in many fields, especially hydrogen evolution reaction (HER), which has been regarded as an effective technology for renewable energy. However, its activity is limited by edge sites, to the disadvantage of atomic economy. Herein, combination with theoretical calculation, we propose that rare-earth element (Ce, La, and Tb) synergy with defect can optimize bulk site of MoS2 for HER. Furthermore, self-supporting electrode was designed for integrating the optimized activity site, leading to an excellent HER performance. Compared to La, Tb, and pristine MoS2, the Ce-based MoS2 synergy with defect has a better activity with an overpotential of 165 mV to achieve 100 mA cm−2, close to the state-of-the-art noble metal Pt.

Exploitation of the Large-Area Basal Plane of MoS2 and Preparation of Bifunctional Catalysts through On-Surface Self-Assembly.

The development of nonprecious electrochemical catalysts for water splitting is a key step to achieve a sustainable energy supply for the future. Molybdenum disulfide (MoS2) has been extensively studied as a promising low‐cost catalyst for hydrogen evolution reaction (HER), whereas HER is only catalyzed at the edge for pristine MoS2, leaving a large area of basal plane useless. Herein, on‐surface self‐assembly is demonstrated to be an effective, facile, and damage‐free method to take full advantage of the large ratio surface of MoS2 for HER by using multiscale simulations. It is found that as supplement of edge sites of MoS2, on‐MoS2 M(abt)2 (M = Ni, Co; abt = 2‐aminobenzenethiolate) owns high HER activity, and the self‐assembled M(abt)2 monolayers on MoS2 can be obtained through a simple liquid‐deposition method. More importantly, on‐surface self‐assembly provides potential application for overall water splitting once the self‐assembled systems prove to be of both HER and oxygen evolution reaction activities, for example, on‐MoS2 Co(abt)2. This work opens up a new and promising avenue (on‐surface self‐assembly) toward the full exploitation of the basal plane of MoS2 for HER and the preparation of bifunctional catalysts for overall water splitting.

Mechanical bending induced catalytic activity enhancement of monolayer 1 T’-MoS2 for hydrogen evolution reaction

In this paper, mechanisms behind enhancement of catalytic activity of MoS2 mono-layer (three atomic layers) for hydrogen evolution reaction (HER) by mechanically applying bending strain were investigated using density functional theory. Results showed that with the increase of bending strains, the Gibbs free energy for hydrogen adsorption on the MoS2 mono-layer was decreased from 0.18 to −0.04 eV and to 0.13 eV for the bend strains applied along the zigzag and armchair directions, respectively. The mechanism for the enhanced catalytic activity comes from the changes of density of electronic states near the Fermi energy level, which are induced by the changes of the Mo-S and Mo-Mo bonds upon bending. This report provides a new design methodology to improve the catalytic activity of catalysts based on two-dimensional transition metal dichalcogenides through a simple mechanical bending.

Oriented Stacking along Vertical (002) Planes of MoS2: A Novel Assembling Style to Enhance Activity for Hydrogen Evolution

The layered structures of MoS2 tend to stack and aggregate and result in decreasing of rims and edges of MoS2 nanosheets, which greatly limited the improvement of activity of MoS2 as electrocatalysts for hydrogen evolution reaction (HER). Herein, owing to the inert nature of (002) basal plane of MoS2 for HER, we propose that oriented stacking along vertical (002) plane can form nanocolumn structure, which may expose an increased number of the active sites per mass and accelerate charge transfer rate for HER. The electrochemical measurements confirm that the nanocolumns of oriented stacking of MoS2 (O-MoS2) have much better HER activity than bulk MoS2 and randomly stacking of MoS2 with about 25 times enhancement of electrochemically active surface area (ECSA). Therefore, assembling style along vertical inert plane may be a novel way to enhance HER performances of layered transition metal sulfides.