Synthesis and photocatalytic hydrogen activity of Mo1−xS2 nanosheets with controllable Mo vacancies
TL;DR: In this paper, a novel Mo1−xS2 (Mo1−S2/TiO2) with controllable Mo vacancies was successfully synthesized by simple NaBH4 treatment, which exhibits significantly enhanced hydrogen evolution reaction (HER) activity with lower overpotential and smaller Tafel slope in alkaline electrolyte.
About: This article is published in Journal of Alloys and Compounds.The article was published on 2021-09-25. It has received 15 citations till now. The article focuses on the topics: Tafel equation & Overpotential.
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TL;DR: In this article , a Frenkel-defected monolayer MoS2 catalyst was proposed, in which a fraction of Mo atoms in MoS 2 spontaneously leave their places in the lattice, creating vacancies and becoming interstitials by lodging in nearby locations.
Abstract: Defect engineering is an effective strategy to improve the activity of two-dimensional molybdenum disulfide base planes toward electrocatalytic hydrogen evolution reaction. Here, we report a Frenkel-defected monolayer MoS2 catalyst, in which a fraction of Mo atoms in MoS2 spontaneously leave their places in the lattice, creating vacancies and becoming interstitials by lodging in nearby locations. Unique charge distributions are introduced in the MoS2 surface planes, and those interstitial Mo atoms are more conducive to H adsorption, thus greatly promoting the HER activity of monolayer MoS2 base planes. At the current density of 10 mA cm-2, the optimal Frenkel-defected monolayer MoS2 exhibits a lower overpotential (164 mV) than either pristine monolayer MoS2 surface plane (358 mV) or Pt-single-atom doped MoS2 (211 mV). This work provides insights into the structure-property relationship of point-defected MoS2 and highlights the advantages of Frenkel defects in tuning the catalytic performance of MoS2 materials.
70 citations
TL;DR: In this paper, a facile hydrazine hydrate-assisted method is reported to synthesize sulfur-rich MoS2, which exhibits a low overpotential of 173mV at a current density of 10mV, a small Tafel slope of 56.6mV dec−1, and long-term stability in 0.5m H2SO4 solution.
12 citations
TL;DR: In this article , a novel Mo vacancy defective MoS2/CdS composites were obtained by a facile hydrothermal method and the photocatalytic performance of the prepared composites was evaluated from the perspective of decomposing water to produce H2.
8 citations
TL;DR: In this paper, Z-scheme MoS2/g-C3N4 heterojunction was fabricated to enhance removal of U(VI) from aqueous solution.
Abstract: Graphitic carbon nitride (g-C3N4) has been paid increasingly attentions in U(VI) removal due to the visible-light response, whereas the high recombination of photogenerated electron and holes limited the actual environmental application. Herein, Z-scheme MoS2/g-C3N4 heterojunction was fabricated to enhance removal of U(VI) from aqueous solution. The microscopic and spectroscopic characterizations showed that addition of MoS2 on surface of g-C3N4 increased separation efficiency of photogenerated charge, decreased the bandgap and improved the intensity of light adsorption. Approximate 82% of UO22+ was photo-reduced by MoS2/g-C3N4 after 1 h of light irradiation at pH 4.5. The high effective photocatalytic reduction of U(VI) on MoS2/g-C3N4 was attributed to ·O2− radials according to quenching experiments. XPS analysis showed that the adsorbed U(VI) was photo-reduced into U(IV). These findings are crucial for the design of C3N4-based composites with high efficient photocatalytic performance and exclusive selectivity into actual environmental cleanup.
6 citations
TL;DR: In this paper , a ternary photocatalysts with defect MoS2 and Ti3C2 acting synergistically on CdS are explored, and the experimental results showed that the Defect MoS 2/Ti 3C2/CdS photocatalyst had excellent photocatalysis hydrogen production performance of 14.1 mmol h−1g−1.
6 citations
References
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TL;DR: Structural characterization and electrochemical studies confirmed that the nanosheets of the metallic MoS2 polymorph exhibit facile electrode kinetics and low-loss electrical transport and possess a proliferated density of catalytic active sites, which make these metallic nanOSheets a highly competitive earth-abundant HER catalyst.
Abstract: Promising catalytic activity from molybdenum disulfide (MoS2) in the hydrogen evolution reaction (HER) is attributed to active sites located along the edges of its two-dimensional layered crystal structure, but its performance is currently limited by the density and reactivity of active sites, poor electrical transport, and inefficient electrical contact to the catalyst. Here we report dramatically enhanced HER catalysis (an electrocatalytic current density of 10 mA/cm2 at a low overpotential of −187 mV vs RHE and a Tafel slope of 43 mV/decade) from metallic nanosheets of 1T-MoS2 chemically exfoliated via lithium intercalation from semiconducting 2H-MoS2 nanostructures grown directly on graphite. Structural characterization and electrochemical studies confirmed that the nanosheets of the metallic MoS2 polymorph exhibit facile electrode kinetics and low-loss electrical transport and possess a proliferated density of catalytic active sites. These distinct and previously unexploited features of 1T-MoS2 make ...
2,899 citations
TL;DR: In this article, a solvent-evaporation-assisted intercalation method was introduced to fabricate the hybrid of alternating molybdenum disulfide (MoS2) sheets and reduced graphene oxide layers, in which the nanosize of the MoS2 nanosheets can be effectively controlled by leveraging the confinement effect within the two-dimensional graphene layers.
Abstract: Since the electrocatalytic activity of layered molybdenum disulfide (MoS2) for hydrogen evolution reaction (HER) closely depends on its exposed edges, the morphology and size of the material are critically important. Herein, we introduce a novel solvent-evaporation-assisted intercalation method to fabricate the hybrid of alternating MoS2 sheets and reduced graphene oxide layers, in which the nanosize of the MoS2 nanosheets can be effectively controlled by leveraging the confinement effect within the two-dimensional graphene layers. Significantly, the resulting MoS2/reduced graphene oxide (RGO) composite shows excellent catalytic activity for HER characterized by higher current densities and lower onset potentials than the conventional pre-exfoliated RGO supported MoS2 nanosheets. Further experiments on the effect of oxidation degree of graphene, the crystallinity of MoS2, and the exposed active site density on the HER performance of the MoS2/RGO composites show that there is an optimum condition for the c...
612 citations
TL;DR: In this article, a combined theoretical and experimental approach was proposed to improve the sluggish HER kinetics of MoS2 electrocatalysts through engineering the water dissociation sites by doping Ni atoms into MoS 2 nanosheets.
Abstract: Earth-abundant MoS2 is widely reported as a promising HER electrocatalyst in acidic solutions, but it exhibits extremely poor HER activities in alkaline media due to the slow water dissociation process. Here we present a combined theoretical and experimental approach to improve the sluggish HER kinetics of MoS2 electrocatalysts through engineering the water dissociation sites by doping Ni atoms into MoS2 nanosheets. The Ni sites thus introduced can effectively reduce the kinetic energy barrier of the initial water-dissociation step and facilitate the desorption of the −OH that are formed. As a result, the developed Ni-doped MoS2 nanosheets (Ni-MoS2) show an extremely low HER overpotential of ∼98 mV at 10 mA cm−2 in 1 M KOH aqueous solution, which is superior to those (>220 mV at 10 mA cm−2) of reported MoS2 electrocatalysts.
455 citations
TL;DR: In this paper, a novel oxygen vacancy-rich two-dimensional/two-dimensional (2D/2D) BiOCl-g-C3N4 ultrathin heterostructure nanosheet (CN-BC) was successfully prepared by a facile solvothermal method for degradation of non-dye organic contaminants.
Abstract: Photocatalytic degradation has been unearthed as a promising strategy for environmental remediation, and the calling is endless for more efficient photocatalytic system. In this study, a novel oxygen vacancy-rich two-dimensional/two-dimensional (2D/2D) BiOCl-g-C3N4 ultrathin heterostructure nanosheet (CN-BC) is successfully prepared by a facile solvothermal method for degradation of non-dye organic contaminants. HRTEM observes the formation of heterojunction, while ESR and XPS unveil the distinct oxygen vacancy concentrations. Density functional calculations reveal that the introduction of oxygen vacancies (OVs) brings a new defect level, resulting in the increased photoabsorption. Under visible light irradiation, the OVs-rich optimum ratio of CN-BC (50CN-50BC) Exhibits 95% removal efficiency of 4-chlorophenol within 2 h, which is about 12.5, 5.3 and 3.4 times as that of pure BiOCl, g-C3N4 and OVs-poor heterostructure, respectively. The photocatalytic mechanism of OVs-rich 50CN-50BC is also revealed, suggesting that the synergistic effect between 2D/2D heterojunction and oxygen vacancies greatly promotes visible-light photoabsorption and photoinduced carrier separation efficiency with a prolonged lifetime, which is confirmed by multiple optical and electrochemical analyses, including DRS, steady-state photoluminescence spectra, electrochemical impedance spectroscopy, photocurrent response and time-resolved fluorescence spectra. This study could bring new opportunities for the rational design of highly efficient photocatalysts by combining 2D/2D heterojunctions with oxygen vacancies in environmental remediation.
451 citations
379 citations