Vanadium doped few-layer ultrathin MoS2 nanosheets on reduced graphene oxide for high-performance hydrogen evolution reaction (original) (raw)
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Chemistry of Materials, 2016
Herein, we report a unique thermal synthesis method to prepare a novel two-dimensional (2D) hybrid nanostructure consisted of ultrathin and tiny-sized molybdenum disulfide nanoplatelets homogenously inlaid in graphene sheets (MoS /G) with excellent electrocatalytic performance for HER. In this process, molybdenum oleate served as the source of both molybdenum and carbon, while crystalline sodium sulfate (Na 2 SO 4) served as both reaction template and sulfur source. The remarkable integration of MoS 2 and graphene in well-assembled 2D hybrid architecture provided large electrochemically active surface area and a huge number of active sites and also exhibited extraordinary collective properties for electron transport and H + trapping. The MoS 2 /G inlaid nanosheets deliver ultrahigh catalytic activity towards HER among the existing electrocatalysts with similar compositions, presenting a low onset overpotential approaching 30 mV, a current density of 10 mA/cm 2 at ~110 mV, and a Tafel slope as small as 67.4 mV/dec. Moreover, the strong bonding between MoS 2 nanoplatelets and graphene enabled outstanding long-term electrochemical stability and structural integrity, exhibiting almost 100% activity retention after 1,000 cycles and ~97% after 100,000 seconds of continuous testing (under static overpotential of-0.15 V). The synthetic strategy is simple, inexpensive and scalable for large-scale production, and also can be extended to diverse inlaid 2D nano-architectures with great potential for many other applications.
Nanoscale advances, 2020
In this work we designed a one-pot solvothermal synthesis of MoS 2(1Àx) Se 2x nanosheets directly grown on N-doped reduced graphene oxide (hereafter N-rGO). We optimized the synthesis conditions to control the Se : S ratio, with the aim of tailoring the optoelectronic properties of the resulting nanocomposites for their use as electro-and photoelectro-catalysts in the hydrogen evolution reaction (HER). The synthesis protocol made use of ammonium tetrathiomolybdate (ATM) as MoS 2 precursor and dimethyl diselenide (DMDSe) as selenizing agent. By optimizing growth conditions and post-annealing treatments, we produced either partially amorphous or highly crystalline chalcogen-defective electrocatalysts. All samples were tested for the HER in acidic environment, and the best performing among them, for the photoassisted HER. In low crystallinity samples, the introduction of Se is not beneficial for promoting the catalytic activity, and MoS 2 /N-rGO was the most active electrocatalyst. On the other hand, after the post-annealing treatment and the consequent crystallization of the materials, the best HER performance was obtained for the sample with x ¼ 0.38, which also showed the highest enhancement upon light irradiation.
ACS applied materials & interfaces, 2015
Molybdenum disulfide (MoS2) is a promising catalyst for hydrogen evolution reaction (HER) because of its unique nature to supply active sites in the reaction. However, the low density of active sites and their poor electrical conductivity have limited the performance of MoS2 in HER. In this work, we synthesized MoS2 nanosheets on three-dimensional (3D) conductive MoO2 via a two-step chemical vapor deposition (CVD) reaction. The 3D MoO2 structure can create structural disorders in MoS2 nanosheets (referred to as 3D MoS2/MoO2), which are responsible for providing the superior HER activity by exposing tremendous active sites of terminal disulfur of (in MoS2) as well as the backbone conductive oxide layer (of MoO2) to facilitate an interfacial charge transport for the proton reduction. In addition, the MoS2 nanosheets could protect the inner MoO2 core from the acidic electrolyte in the HER. The high activity of the as-synthesized 3D MoS2/MoO2 hybrid material in HER is attributed to the ...
Defect-Rich Heterogeneous MoS2/rGO/NiS Nanocomposite for Efficient pH-Universal Hydrogen Evolution
Nanomaterials, 2021
Molybdenum disulfide (MoS2) has been universally demonstrated to be an effective electrocatalytic catalyst for hydrogen evolution reaction (HER). However, the low conductivity, few active sites and poor stability of MoS2-based electrocatalysts hinder its hydrogen evolution performance in a wide pH range. The introduction of other metal phases and carbon materials can create rich interfaces and defects to enhance the activity and stability of the catalyst. Herein, a new defect-rich heterogeneous ternary nanocomposite consisted of MoS2, NiS and reduced graphene oxide (rGO) are synthesized using ultrathin αNi(OH)2 nanowires as the nickel source. The MoS2/rGO/NiS-5 of optimal formulation in 0.5 M H2SO4, 1.0 M KOH and 1.0 M PBS only requires 152, 169 and 209 mV of overpotential to achieve a current density of 10 mA cm−2 (denoted as η10), respectively. The excellent HER performance of the MoS2/rGO/NiS-5 electrocatalyst can be ascribed to the synergistic effect of abundant heterogeneous in...
ACS Applied Nano Materials, 2018
We report the hydrogen evolution reaction (HER) with molybdenum diselenide (MoSe 2) and its reduced graphene oxide (rGO) hybrids synthesized by a microwave process followed by annealing at 400°C. The content of GO was varied to understand its role in the electrocatalytic activities. Electrochemical performance of the as-synthesized and the annealed catalysts underscores (i) a requirement of catalytic activation of the as-synthesized samples, (ii) an apparent shift in the onset potential as a result of annealing, and (iii) striking changes in the Tafel slope as well as the overpotential. The results clearly reveal that partially crystalline plain MoSe 2 is more elctroactive in comparison to its annealed counterpart, whereas annealing is advantageous to MoSe 2 /rGO. Improved HER performances of the annealed MoSe 2 /rGO hydrids arise from the synergistic effect between active MoSe 2 and rGO of improved conductivity. The annealed hybrid of MoSe 2 with rGO designated as MoSe 2 / rGO100_400°C demonstrated an excellent HER activity with a small onset potential of −46 mV vs reversible hydrogen electrode, a smaller Tafel slope (61 mV/dec), and a reduced overpotential of 186 mV at −10 mA/cm 2. As a result of a convenient synthetic process and the suitable electrocatalytic performance, this study would be beneficial to designing and fabricating other nanomaterials with/without a conductive support for their versatile applications.
Materials Chemistry and Physics, 2020
Synthesis of Palladium nanoparticle mono dispersed on MoS 2 /N,S-rGO composite. � Dual doping of graphene oxide with Nitrogen and Sulfur provide higher surface area. � Good electronic interactions between the active material Pd and the support material. � Structural transformation in MoS 2 (2T MoS 2 to 1T MoS 2) and sulfur vacancy formation was observed after introduction of Pd NP. � The as-synthesized Pd-MoS 2 /N,S-rGO shows lower Tafel slope value of 38 mv. dec À 1 and overpotential of À 42 mv at 10 mA/cm 2 .
2018
We designed solution-processed, flexible hybrid graphene flake/2H-MoS2 quantum dot (QD) heterostructures, showing enhanced electrocatalytic activity for the hydrogen evolution reaction (HER) with respect to their native individual components. The 2H-MoS2 QDs are produced through a scalable, environmentally friendly, one-step solvothermal approach from two-dimensional (2D) 2H-MoS2 flakes obtained by liquid phase exfoliation (LPE) of their bulk counterpart in 2-Propanol. This QDs synthesis avoids the use of high boiling point and/or toxic solvents. Graphene flakes are produced by LPE of graphite in N-Methyl-2-pyrrolidone. The electrochemical properties of 2H-MoS2 QDs and their HER-favorable chemical and electronic coupling with graphene enable to reach a current density of 10 mA/cm^2 at an overpotential of 136 mV, surpassing the performances of graphene flake/2H-MoS2 (1T-MoS2) flake heterostructures. Our approach provides a shortcut, viable and cost-effective method for enhancing the ...
Hydrothermal synthesis of 2D MoS2 nanosheets for electrocatalytic hydrogen evolution reaction
Nanostructured molybdenum disulfide (MoS2) is a very promising catalyst for producing molecular hydrogen by electrochemical methods. Herein, we have designed and synthesized highly electocatalytically active 2D MoS2 nanosheets (NS) from molybdenum trioxide (MoO3) by a facile hydrothermal method and have compared their electrocatalytic activities for hydrogen evolution reaction (HER). The electrochemical characterization was performed using linear sweep voltammetry (LSV) in acidic medium. The MoS2 NS show a HER onset potential at about 80 mV vs. reversible hydrogen electrode (RHE) which is much lower than MoO3 (300 mV). The MoS2 NS and MoO3 show a current density of 25 mA cm2 and 0.3 mA cm2, respectively at an overpotential of 280 mV vs. RHE. The MoS2 NS showed an 83 times higher current density when compared to MoO3. The Tafel slopes of the MoS2 NS and MoO3 were about 90 mV per dec and 110 mV per dec respectively. This suggests that MoS2 NS are a better electrocatalyst when compared to MoO3 and follow the Volmer–Heyrovsky mechanism for HER.
Highly active and stable electrocatalysts of FeS2–reduced graphene oxide for hydrogen evolution
Journal of Materials Science, 2018
Electrocatalytic hydrogen evolution is the most cost-effective method for producing hydrogen as a large-scale clean energy source. Thus, catalysts of low-cost hydrogen evolution are developing at great speed. FeS 2-reduced graphene oxide (RGO) hybrid catalysts are synthesized with the use of abundant and inexpensive component worldwide. The catalyst has satisfactory electrocatalytic performance and excellent stability in 0.5 M H 2 SO 4 solution. The catalyst supported by RGO is the ideal electrocatalyst with satisfactory electrical conductivity with 61 mV dec-1 of the Tafel slope. What is more, the current density changes slightly in 36 h and the catalytic performance is relatively stable at 200 mV overpotential. Therefore, the catalyst supported by RGO has high potential for industrial production due to its simple composition and satisfactory electrocatalytic effect.