Pristine MoS2 Research Articles

Efficient photoelectrochemical water splitting and photocatalytic performance for graphene-bridged MoS2–Fe2O3 nanocomposite under visible light active: Insights into photocatalysis mechanism

In this work, we aim to design a new nanocomposite with an improved photocatalytic performance by the synergistic formation of a Z-scheme photocatalytic system with graphene-bridged molybdenum disulfide (MoS2) and iron oxide (Fe2O3). We fabricated graphene-bridged MoS2–Fe2O3 nanocomposites by a simple hydrothermal method for enhanced photoelectrochemical (PEC) performance and higher degradation of TC. This nanocomposite can increase carrier separation efficiency. Moreover, the photocatalysts exhibit excellent oxidation and reduction rates capabilities assessed by photocatalytic and photoelectrochemical experiments under visible light illumination. The photocatalyst showed 97% removal capability of tetracycline and photocurrent density is five times higher than of bare Fe2O3. The active specie of .O2− and ⋅OH radicals was detected by the ESR instruments during photocatalytic activity improvement that could confirm the constructed Z-scheme MoS2–Fe2O3-Graphene nanocomposite showed that two folds photocatalytic degradation greater than those of pristine MoS2 and Fe2O3. According to the results shows UV–Visible spectroscopy, photoluminescence spectroscopy, Electron impendence spectroscopy, and photocurrent response, the photo-response electrons of transfer from the conduction band of Fe2O3 could fast transport in the valence band of MoS2. The graphene bridge served as a charge-migrate channel between two materials, and the electrons in protonated MoS2 and Fe2O3 achieved a charge balance. This work provides a new strategy for further design of high-efficiency of MFG nanocomposite with graphene as the electronic mediator for environmental remediation.

Efficient recovery of gold from low concentration Au(S2O3)23– solution by fabricating Ag/MoS2 Ohmic contact

The surface decoration of precious metal particles is one of the most effective strategies for improving the photocatalytic activity of semiconductors. In this work, a MoS2-based Ohmic contact was fabricated by depositing Ag nanoparticles on the surface of MoS2 nanosheets (MoS2 NSs) to enhance the photoreduction of Au(Ⅰ) from a low concentration Au(S2O3)23– solution. After the fabrication of Ohmic contact, more efficient interface charge transfer can be achieved under the drive of built-in electric field. As a result, the photogenerated singlet excitons in MoS2 NSs are readily dissociated into free charges with the electrons drifting to Ag NPs, leading to a higher electron concentration on the surface of Ag/MoS2 NSs. The gold recovery of Ag/MoS2 NSs-4.15% reaches up to 96.67% for the low concentration Au(S2O3)23– solution, which is about 3.9 times higher than that of pristine MoS2 NSs (24.82%). The results of this work are encouraging for further development in the surface science of photocatalysis and demonstrate a pathway for efficient gold recovery via photoreduction.

A Novel MoS2/TiO2/Graphene Nanohybrid for Enhanced Photocatalytic Hydrogen Evolution under Visible Light Irradiation

Graphene is regarded as a potential co-photocatalyst for photocatalytic hydrogen (H2) evolution, but its great photocatalytic ability requires tuning the band gap structure or design morphology of composites. In this study, MoS2/TiO2/graphene (MTG) nanohybrids were fabricated at varied ratios of graphene and served as co-photocatalysts for H2 evolution. The results exhibited that the H2 evolution of MTG-10 obtained is much better than others. The amount of hydrogen evolution was high, which was found to be 4122 μmol g−1 of H2 in 5 h with photocatalytic systems, which is almost 7.5~13.4 times greater than that of previous pristine MoS2 (548 μmol g−1) and TiO2 (307 μmol g−1) samples, respectively. This is significantly attributed to the graphene as a bridge of MoS2/TiO2 and the incorporation of graphene, suggesting the synergistic effect of the rapid electron-transferring of photoinduced electrons and holes and the powerful electron-collecting of graphene, suppressing the charge recombination rate.

Escalating Catalytic Activity for Hydrogen Evolution Reaction on MoSe2@Graphene Functionalization.

Developing highly efficient and durable hydrogen evolution reaction (HER) electrocatalysts is crucial for addressing the energy and environmental challenges. Among the 2D-layered chalcogenides, MoSe2 possesses superior features for HER catalysis. The van der Waals attractions and high surface energy, however, stack the MoSe2 layers, resulting in a loss of edge active catalytic sites. In addition, MoSe2 suffers from low intrinsic conductivity and weak electrical contact with active sites. To overcome the issues, this work presents a novel approach, wherein the in situ incorporated diethylene glycol solvent into the interlayers of MoSe2 during synthesis when treated thermally in an inert atmosphere at 600 °C transformed into graphene (Gr). This widened the interlayer spacing of MoSe2, thereby exposing more HER active edge sites with high conductivity offered by the incorporated Gr. The resulting MoSe2-Gr composite exhibited a significantly enhanced HER catalytic activity compared to the pristine MoSe2 in an acidic medium and demonstrated a superior HER catalytic activity compared to the state-of-the-art Pt/C catalyst, particularly at a high current density beyond ca. 55 mA cm-2. Additionally, the MoSe2-Gr catalyst demonstrated long-term electrochemical stability during HER. This work, thus, presents a facile and novel approach for obtaining an efficient MoSe2 electrocatalyst applicable in green hydrogen production.

Enhanced photocatalytic H2 production of flower-like MoS2@Ag2S photocatalysts with matched band structures

The flower-like MoS2@Ag2S (MS@AS) photocatalyst was synthesized by the hydrothermal and ion exchange reactions. Results of SEM, TEM, elemental line scan profiles, and XPS analysis revealed that Ag2S nanoparticles were attached to flower-like MoS2. Raman spectra confirm that MoS2 (MS) and MoS2@Ag2S (MS@AS) photocatalysts are hybrid phases of 1 T-MoS2 and 2H-MoS2. Compared with pristine MoS2, the shifts of XPS Mo3d and S2s peaks of MS@AS photocatalyst indicate the interaction between MoS2 and Ag2S (or Ag). The band structure of the photocatalyst is proposed based on the UPS spectrum and Tauc plot of MoS2 and Ag2S. The H2 production efficiency of MoS2@Ag2S photocatalyst reaches 3516 μmol·g−1·h−1, better than that of MoS2. The MoS2@Ag2S photocatalyst exhibits a S-scheme band structure, which can facilitate electron-hole separation and improves photocatalytic H2 production activity.

Z-scheme driven of MoS2/Co3O4 nano-heterojunction for efficient photocatalysis hydrogen evolution and Rhodamine B degradation

In this work, we reported a promising process for the fabrication of MoS2/Co3O4 nano-heterojunction for greatly effective photocatalysis performance. Especially, the optimized nanocomposites display great hydrogen production capability, which is over 13.4-folds and 11.5-folds (MoS2/Co3O4 nano-heterojunction) greater than that of pristine MoS2 and pristine Co3O4 catalysts, respectively. The as-fabricated MoS2/Co3O4 nanocomposites exhibit excellent operation towards hydrogen production (3,825 μmol/g) and Rhodamine B（RhB) photodegradation (Kapp constant of 0.04 min−1), which are nearly one order of magnitude larger than the traditional pristine MoS2 and Co3O4 photocatalysts, respectively. The delivery pathway of photoinduced charges, the production route and the capacity of numerous reactive species (like.O2−, and.OH radical) are itemized and considered. This effort provides a new perspective for the construction and design of a more powerful nano-heterojunction photocatalyst with robust visible light absorption ability.

Patching sulfur vacancies: A versatile approach for achieving ultrasensitive gas sensors based on transition metal dichalcogenides

Transition metal dichalcogenides (TMDCs) garner significant attention for their potential to create high-performance gas sensors. Despite their favorable properties such as tunable bandgap, high carrier mobility, and large surface-to-volume ratio, the performance of TMDCs devices is compromised by sulfur vacancies, which reduce carrier mobility. To mitigate this issue, we propose a simple and universal approach for patching sulfur vacancies, wherein thiol groups are inserted to repair sulfur vacancies. The sulfur vacancy patching (SVP) approach is applied to fabricate a MoS2-based gas sensor using mechanical exfoliation and all-dry transfer methods, and the resulting 4-nitrothiophenol (4NTP) repaired molybdenum disulfide (4NTP-MoS2) is prepared via a sample solution process. Our results show that 4NTP-MoS2 exhibits higher response (increased by 200 %) to ppb-level NO2 with shorter response/recovery times (61/82 s) and better selectivity at 25 °C compared to pristine MoS2. Notably, the limit of detection (LOD) toward NO2 of 4NTP-MoS2 is 10 ppb. Kelvin probe force microscopy (KPFM) and density functional theory (DFT) reveal that the improved gas sensing performance is mainly attributed to the 4NTP-induced n-doping effect on MoS2 and the corresponding increment of surface absorption energy to NO2. Additionally, our 4NTP-induced SVP approach is universal for enhancing gas sensing properties of other TMDCs, such as MoSe2, WS2, and WSe2.

Reversible room temperature ammonia sensor based on the synthesized MoS2/PANI nanocomposites

Successful fabrication and optimization of molybdenum disulfide (MoS2)/polyaniline (PANI) nanocomposite-based room temperature ammonia sensors have been reported in this work. The hydrothermal technique was used to synthesize nanocomposites of MoS2 and PANI at different amounts of PANI. For this, the precursor values were changed by choosing three different values of 0.65 (MP1), 1.1 (MP2), and 2.2 (MP3) for the ammonium heptamolybdate/PANI weight ratio. Successful fabrication of nanocomposites was confirmed by Raman analysis and x-ray diffraction. According to FESEM images, MoS2/PANI nanocomposites have been composed of 1D-PANI nanofibers covered by 2D-MoS2 nanosheets and created a porous morphology that influenced their sensing characteristics significantly. The samples’ ability to detect ammonia at room temperature was examined by fabricating sensor devices using the synthesized MoS2, PANI, and nanocomposites. The fabricated sensor using MP2 showed much better gas-sensing properties than other samples. This sensor showed about 4.6 and 1.6 times higher response than pristine PANI and MoS2 sensors for 10 ppm of ammonia, respectively, with better selectivity toward ammonia than other gas species. This research shows that compositing PANI with MoS2 significantly improves the gas detection performance of MoS2.

Spectro-Microscopic Perceptions into Oxidation Behavior of Large-Scale Molybdenum Disulfide and its Photoelectrical Correlation.

Despite the encouraging properties and research of 2D MoS2 , an ongoing issue associated with the oxidative instability remains elusive for practical optoelectronic applications. Thus, in-depth understanding of the oxidation behavior of large-scale and homogeneous 2D MoS2 is imperative. Here the structural and chemical transformations of large-area MoS2 multilayers by air-annealing with altered temperature and time via combinatorial spectro-microscopic analyses (Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy) are surveyed. The results gave indications pertaining to temperature- and time-dependent oxidation effects: i) heat-driven elimination of redundant residues, ii) internal strain stimulated by the formation of MoO bonds, iii) deterioration of the MoS2 crystallinity, iv) layer thinning, and v) morphological transformation from 2D MoS2 layers to particles. Photoelectrical characterization of the air-annealed MoS2 is implemented to capture the link between the oxidation behavior of MoS2 multilayers and their photoelectrical properties. The photocurrent based on MoS2 air-annealed at 200°C is assessed to be 4.92µA, which is 1.73 times higher than that of pristine MoS2 (2.84µA). The diminution in the photocurrent of the photodetector based on MoS2 air-annealed above 300°C in terms of the structural, chemical, and electrical conversions induced by the oxidation process is further discussed.

Vinyl-Flanked Diketopyrrolopyrrole Polymer/MoS2 Hybrid for Donor–Acceptor Semiconductor Photodetection

Polymers containing the 1,4-diketo-pyrrolo[3,4-c]pyrrole (diketopyrrolopyrrole, DPP) unit are highly desirable for optoelectronic devices. However, the requirements for the substituents flanking the DPP unit at the 3,6-positions are limited to aryl groups due to the lack of synthetic methods to prepare other substituted DPP. This paper describes the synthesis, characterization, and application of the first vinyl-flanked DPP polymers: DPP-vinyl-thiophene-vinyl (PDPPVTV) and DPP-vinyl-thiophene-thiophene (PDPPVTT). The position of the vinyl group is varied to determine its effect on the physical and optoelectrical properties of the polymers. The semicrystalline polymers record moderate molecular weights (Mn ∼ 25–30 kDa), good solubility in chloroform, and high thermal stabilities (Td onset ∼ 400 °C). Both polymers have broad absorption bands in the solid state (abs λmax ∼ 800 nm) that extend into the near-infrared (NIR) region (900–1000 nm). PDPPVTT has two orders of magnitude higher hole mobility than PDPPVTV (0.25 vs 0.0018 cm2 V–1 s–1) and is used as a coating material in a MoS2 FET device. The PDPPVTT/2D MoS2 hybrid device shows higher photoresponsivity in the NIR region (103 A/W at 800 nm and 102 A/W at 1050 nm) than the pristine MoS2 photodetector (102 A/W at 800 nm and 0 A/W at 1050 nm).

Boosting photocatalytic dehydrogenation and simultaneous selective oxidation of benzyl alcohol to benzaldehyde over flower-like MoS2 modified Zn0.5Cd0.5S solid solution

A series of MoS2/Zn0.5Cd0.5S with varying concentrations of flower-like MoS2 is prepared based on a simple and practical method with highly efficient photocatalytic dehydrogenation and simultaneous selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). A comparative study between the composites and their two components (pristine MoS2 and Zn0.5Cd0.5S) is carried out for various structural, optical, electrical, and photocatalytic characterization. The studies reveal that the size of Zn0.5Cd0.5S nanoparticles is in the order of 3∼5 nm and is distributed uniformly over the surface of the flower-like 350 nm sized MoS2. The optical research conducted using UV–vis diffuse reflectance spectroscopy reflecting an excellent photoresponse by the MoS2/Zn0.5Cd0.5S. The photoelectrochemical tests showed that the adding of proper ratio of flower-like MoS2 (6%) results in an efficient separation and migration of photogenerated carriers for pristine Zn0.5Cd0.5S nanoparticles. The photocatalytic dehydrogenation rate of BA for the 6%-MoS2/Zn0.5Cd0.5S is the highest at 3.03 mmol g−1 h−1, meanwhile the yield of BAD and the selective conversion of BA to BAD are 49.3% and 100%, respectively. The essential stages of the photocatalytic dehydrogenation of BA are ·C caused by the photo-generated holes, according to the EPR spectra of the PBN-carbon centered radical (PBN–C). Besides, the mechanism for improved photocatalytic dehydrogenation and synergistic selective oxidation of BA to BAD with flower-like MoS2 modified Zn0.5Cd0.5S nanoparticles was systematically studied through gas chromatography-mass spectrometry analysis and first principle density functional theory calculations. The highly efficient dehydrogenation and synergistic selective oxidation of BA to BAD for MoS2/Zn0.5Cd0.5S are mainly attributed to the introduction of MoS2 nanoflowers that can provide abundant active sites, and formed MoS2/Zn0.5Cd0.5S heterostructures could further promote the separation of photogenerated electron-hole pairs. Moreover, the valance band position of the 6%-MoS2/Zn0.5Cd0.5S is more positive, so the hole at the VB position has the stronger ability to oxidize BA. This study provides a feasible method for efficiently photocatalytic dehydrogenation synergism selective oxidation of organic substrates into valuable products.

Nanoarchitectonic Ni-doped edge dislocation defect-rich MoS2 boosting catalytic activity in electrochemical hydrogen production

The world is moving towards a more sustainable future, and hydrogen is emerging as a key player in this transition. Hydrogen production through the use of electrocatalysts is becoming increasingly popular as a sustainable and efficient method. Herein, we report the monodisperse nickel (Ni) nanoparticles incorporated molybdenum disulfide (MoS2) (Ni/MoS2) electrocatalyst synthesized via a hydrothermal method, followed by an annealing process. It is found that the edge dislocations which are topological defects that occur when a crystal lattice has an extra plane of atoms. These defects can drastically affect the chemical properties and electronic structure of materials, which can improve their electrocatalytic performance. However, defect-rich electrocatalysts for hydrogen evolution reaction (HER) is becoming more popular nowadays. It is not yet clear how the active sites of the edge dislocations of MoS2 affect the catalytic properties of hydrogen evolution. The most promising electrocatalyst without precious metals is considered to be metallic MoS2 (1T phase), which exhibits Pt-like HER performance in alkaline media. One of the expected functions of MoS2 is to act as a conductive support with relatively large surface area for more catalytically active and highly dispersed Ni species. The 1T-MoS2 exhibits remarkable catalytic properties for HER due to the abundance of active sites connected by edge dislocations. Compared with pristine MoS2, the edge dislocation defect-rich Ni/MoS2 shows the outstanding HER activity, delivering a current density of 10 mA cm−2 at an overpotential of only 89 mV with a lower Tafel slope of 59 mV dec−1. Additionally, chronopotential analysis is performed at a constant current density of 10 mA cm−2 for 30 h with minimal loss in overpotential, which demonstrates an extremely potential and stable HER catalyst.

Fast response and high-performance UV-C to NIR broadband photodetector based on MoS2/a-Ga2O3 heterostructures and impact of band-alignment and charge carrier dynamics

Recently, 2D materials have gained tremendous research interest due to their unique properties in electronics and optoelectronics. However, single 2D material-based photodetectors suffer from limitations such as narrow spectral sensitivity and slow response time due to bandgap restriction and difficulty in charge extraction. A heterojunction, which separates photo-excited electron-hole pairs and tunes absorption edge through appropriate selection of semiconductors with complementary bandgaps, is an effective strategy for broad spectral energy-conserving photodetection. This study presents a scalable 2D/3D heterostructure of MoS2/Ga2O3 with outstanding UV-C to NIR broad spectral photoresponse. The MoS2/Ga2O3 photodetector demonstrated a 315-fold increase in responsivity and EQE compared to pristine MoS2 photodetector. The device showed highest responsivity and EQE of 171 AW−1 and 2.4 × 104 % respectively under 900 nm illumination at 5 V bias. The device also exhibits high detectivity (4.6 × 1013 Jones) and fast response time of 97 µs. Moreover, the device is highly stable and shows no performance degradation over time. The device behavior was investigated through energy band diagrams and charge carrier dynamics using photoelectron spectroscopy and Kelvin probe force microscopy to gain intrinsic physical insights. The demonstration of MoS2/Ga2O3 as a high-performance broadband photodetector offers exciting opportunities for efficient optoelectronics and imaging applications.

Niobium incorporation in 2D MoSe2 for lung cancer biomarkers detection: The first-principle study of sensitivity improvement

To investigate the biomarker detection capability of the 2D MoSe2 monolayer as the lung cancer detection sensor, the interaction between the biomarker molecules and the surface of the sensor has been studied by first-principles calculations in three scenarios namely i) pristine MoSe2, ii) Nb-doped MoSe2, iii) Nb-decorated MoSe2 monolayers. In this study, it is proposed that Nb-decorated MoSe2 is a promising biosensor for detecting the two most prominent lung cancer biomarkers in the breath namely 2-butanone (C4H8O) and 1-propanol (C3H8O). The adsorption energy, charge transfer, and the equivalent sensitivity for C3H8O adsorption on Nb-decorated MoSe2 were calculated as −1.907 eV, 0.026e, and 0.14, respectively. Remarkable sensing performance for C4H8O adsorption was observed with an adsorption energy of −1.727 eV, carrying −0.303e from Nb-decorated MoSe2 nanosheet, and enhanced equivalent sensitivity up to 1.24, indicating a much stronger binding between the C4H8O biomarker and Nb-decorated MoSe2.

Metal-organic frameworks derived porous MoS2/CdS heterostructure for efficient photocatalytic performance towards hydrogen evolution and organic pollutants

Photocatalytic technology is a unique method of treating energy crisis and environmental concern. Herein, Metal-organic frameworks (MOFs) were employed to prepare a series of visible light responsive MoS2/CdS heterojunction photocatalysts by facile low-temperature hydrothermal sulfurization. The structural analysis revealed that the prepared MoS2/CdS heterojunction exhibited highly porous structure and the intimate interface was formed between the MoS2 and CdS. For these structure features, the charge separation and transfer were significantly improved, and the MoS2/CdS heterojunction presented efficient photocatalytic activity towards hydrogen evolution and degradation of rhodamine B (RhB) and tetracycline hydrochloride (TC). The highest H2 evolution rate (3318 μmol h−1 g−1) was found at the 5 wt%-MoS2/CdS, which were 10 times and 6 times of pristine MoS2 and CdS, respectively. In particular, the 5 wt%-MoS2/CdS can also remove 95% RhB and 90% TC within 40 min. Moreover, the MoS2/CdS heterojunction showed good photocatalytic stability for hydrogen evolution and degradation of RhB and TC. Furthermore, the radical trapping experiment revealed that the photogenerated · O2− played critical role in RhB degradation and the hole (h+) and · O2− were essential for TC degradation. The work will provide a guidance for rational design and facile preparation of photocatalyst for the visible light-driven hydrogen evolution and elimination of organic pollutants.

Controllable Epitaxial-like Growth of Bi2S3/MoS2 Hybrid Aerogel Nanostructures for Sensitive NO2 Detection at Room Temperature

Constructing heterogeneous interfaces on a nanoscale that can prominently improve the gas-sensing properties has been comprehensively reported. However, the effect of parallel heterostructures formed by unique synthetic means on nitrogen dioxide room-temperature sensing properties still needs to be clarified, which hinders the development of heterostructured hybrid materials in the field of gas sensing. In this study, large-sized MoS2 was parallel-wrapped on the surface of nanoscale Bi2S3 rods, and then, the Bi2S3/MoS2 nanocomposite aerogels were formed by freeze drying and calcination. The NO2 sensing performance of the hybrids and possible surface processes at room temperature have been investigated and deduced. The as-prepared nanocomposite aerogels (Bi2S3/MoS2-2) exhibited a larger specific surface area, a mass of active defect sites, and a higher charge density, thus possessing 15- and 20-times higher response than that of pristine MoS2 nanosheets and Bi2S3 nanorods, respectively. This study provides an efficient way to synthesize large-area parallel heterostructures between two bis-sulfides (Bi2S3 and MoS2), leading to excellent NO2 gas sensing performance.

Electronic and Magnetic Properties of Transition Metal‐Doped MoS2 Monolayer: First‐Principles Calculations

Density functional theory in the framework of generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof to investigate the effects of some selected transition metal (TM) and rare‐earth metal (RE) dopants on the electronic and magnetic properties of a 2D molybdenum disulfide (MoS2) monolayer is reported. The results demonstrate that it is energetically stable to incorporate Ni and Cu in MoS2 structure under Mo‐rich conditions. The pristine MoS2 monolayer has a calculated direct bandgap of 1.70 eV and experiences significant reduction in the gap due to the defects. There is observed induced magnetic behavior due to the tight binding effect originating from the localized dopants and the nearest‐neighbor Mo atoms, with magnetic moments ranging between 0.82 and 3.00 μB. Some of the dopants result in spin polarization which is useful for engineering spin filter devices on magnetic MoS2 nanostructures.

Hydrothermal synthesis of pristine and cobalt doped MoS2 nanosheets for comparative study and application in humidity sensing

In present work, MoS2 nanosheets were produced through a hydrothermal technique using urea surfactant for humidity sensing applications. Also, Cobalt doping was done to study the effects on crystallography, morphology, optical properties and humidity sensing properties of MoS2. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to study crystal structure and morphological analysis. Functional groups were examine through FTIR spectra and Optical properties was observed using UV–Visible. XRD data confirms the hexagonal phase of MoS2 and from SEM images flower-like spheres to wrapped nanosheet structures were observed. Optical band gap was estimated for all samples using UV–Visible data. The comparative analysis of pristine and cobalt-doped MoS2 was discussed here. Also, the humidity sensing behaviour of both pristine and cobalt-doped MoS2 was studied in this paper.

Europium Molybdate/Molybdenum Disulfide Nanostructures with Efficient Electrocatalytic Activity for the Hydrogen Evolution Reaction

The design of hybrid nanostructures of molybdenum disulfide (MoS2) has been extensively explored as potent electrocatalysts for hydrogen generation reactions. Here, we report the in situ synthesis of a nanocomposite containing europium molybdate [Eu2(MoO4)3] and molybdenum disulfide (MoS2) for an enhanced electrochemical hydrogen evolution reaction (HER). The characteristic X-ray diffraction (XRD) peaks of both 2H–MoS2 and α-Eu2(MoO4)3 confirm the formation of the nanocomposite. The nanoflower (NF) architecture of MoS2 coupled with flakes of europium molybdate is observed in the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, which lead to an enhanced surface area of the nanocomposite. Raman and X-ray photoelectron spectroscopy (XPS) studies reveal a variation in the layer thickness of MoS2 and a significant interfacial electronic interaction between Eu2(MoO4)3 and MoS2. As evident from the small onset potential of −0.05 V vs reversible hydrogen electrode (RHE) and a lower overpotential value of 186 mV (at a current density of 10 mA/cm2), the nanocomposite outperforms pristine MoS2 nanoflowers in terms of electrocatalytic HER. The charge-transfer resistance of the nanocomposite (80.02 Ω) is significantly low compared to pristine MoS2 (158.37 Ω), thus confirming the enhanced interfacial charge transfer. The Tafel slope value of the nanocomposite (189 mV/dec) is notably less than that of pristine MoS2 (313 mV/dec), indicating the enhanced HER activity of the nanocomposite. The fabrication of lanthanide-containing MoS2 nanocomposites appears to be promising for an efficient electrocatalytic activity for the hydrogen evolution reaction.

Hot Electron Dynamics in MoS2/Pt Van Der Waals Electrode Interface for Self‐Powered Hot Electron Photodetection

AbstractHot electron photodetection provides a powerful platform for photosensing beyond the bandgap of a semiconductor. High‐performing hot electron photodetection has been reported in 2D transition metal dichalcogenide material‐based devices without the support of plasmonic metal nanostructures but with planar metal electrodes. However, the mechanism driving hot electron dynamics in 2D transition metal dichalcogenide devices has not been explored. Here, we uncover the hot electron transfer in MoS2 and Pt van der Waals (vdW) metal electrodes by transient reflection spectroscopy, revealing a sub‐picosecond transfer time of hot electron and a decelerated recombination process in MoS2 at the below bandgap photoexcitation compared to the pristine MoS2. With an independent photocurrent mapping, the ultralong diffusion is revealed in MoS2/vdW metal electrode and a self‐powered near‐infrared (NIR) photodetector is demonstrated with a high responsivity of 6 mA W−1 and detectivity of 9 × 109 Jones at a wavelength of 1062 nm by integrating Pt and Ag asymmetric vdW electrodes into MoS2. The results will pave the way for the next generation of hot‐electron‐based self‐powered optoelectronic devices.