MoS2 Interlayer Research Articles

Mechanistic Study on Enhanced Electrocatalytic Nitrogen Reduction Reaction by Mo Single Clusters Supported on MoS2.

The electrocatalytic N2 reduction reaction (eNRR) at ambient conditions is an appealing method for NH3 synthesis. It has attracted broad research interest in eNRR catalysts. In this work, by a theoretical study based on density functional calculations, we attributed the higher eNRR activity of defective MoS2 than pure MoS2 to the exposed Mo atom with unsaturated coordination sites in the interlayer of defective MoS2. The finding inspired us to explore the eNRR performance of Mo single atom/clusters with one/more active Mo sites supported on MoS2 [Mon@MoS2 (n = 1∼11)] and the corresponding catalytic mechanism. All considered Mon@MoS2 irrespective of N2 or H adsorption selectivity can achieve higher eNRR activity with lower overpotential and lower NH3 desorption free energy than defective MoS2. The competitive hydrogen evolution reaction can be well suppressed on Mon@MoS2 when n = 2∼10. In particular, Mo9@MoS2 with N2 adsorption selectivity exhibits excellent eNRR activity (η = 0.19 V) and high eNRR selectivity, and it can efficiently desorb the produced NH3 with a low desorption free energy (0.50 eV) to achieve a high ammonia yield with the aid of the produced ammonia molecule in the first eNRR process, which is coadsorbed on the Mo9 single cluster during the later eNRR process. The high eNRR activity of Mon@MoS2 can be attributed to its inherent properties of excellent electrical conductivity, electron accessibility, and multiple exposed Mo active sites available for N-containing species coadsorption. The results demonstrate the significance of H preadsorption, the additional N2 adsorption, and the adsorbed product ammonia in the prior eNRR process in enhancing the overall eNRR performance of different-size single-cluster catalysts. Our work provides a guidance for future study of single-cluster catalysts.

Enhancing the Permselectivity of Thin-Film Composite Membranes Interlayered with MoS2 Nanosheets via Precise Thickness Control.

The demand for highly permeable and selective thin-film composite (TFC) nanofiltration membranes, which are essential for seawater and brackish water softening and resource recovery, is growing rapidly. However, improving and tuning membrane permeability and selectivity simultaneously remain highly challenging owing to the lack of thickness control in polyamide films. In this study, we fabricated a high-performance interlayered TFC membrane through classical interfacial polymerization on a MoS2-coated polyethersulfone substrate. Due to the enhanced confinement effect on the interface degassing and the improved adsorption of the amine monomer by the MoS2 interlayer, the MoS2-interlayered TFC membrane exhibited enhanced roughness and crosslinking. Compared to the control TFC membrane, MoS2-interlayered TFC membranes have a thinner polyamide layer, with thickness ranging from 60 to 85 nm, which can be tuned by altering the MoS2 interlayer thickness. A multilayer permeation model was developed to delineate and analyze the transport resistance and permeability of the MoS2 interlayer and polyamide film through the regression of experimental data. The optimized MoS2-interlayered TFC membrane (0.3-inter) had a 96.8% Na2SO4 rejection combined with an excellent permeability of 15.9 L m-2 h-1 bar-1 (LMH/bar), approximately 2.4 times that of the control membrane (6.6 LMH/bar). This research provides a feasible strategy for the rational design of tunable, high-performance NF membranes for environmental applications.

Highly efficient removal and sequestration of Cr(VI) in confined MoS2 interlayer Nanochannels: Performance and mechanism

Environmental contamination by Cr(VI) is of particular concern because of its severe toxicity and high mobility. In this study, we employed two-dimensional MoS2 nanosheets in the removal of Cr(VI), with an emphasis on revealing the removal mechanisms, and how the compositional and structural uniqueness of 2D MoS2 nanomaterials intrinsically impact the Cr removal efficiency. Through batch experiments with dispersed nanosheets, we found that MoS2 nanosheets exhibited a high Cr(VI) removal capacity at ∼1100 mg/g via a phase-dependent mechanism. Particularly, the 1T polymorph in the MoS2 nanosheets removed Cr(VI) through a redox-reaction mechanism, which was different from the adsorptive removal of Cr(VI) by MoS2 reported previously, highlighting the compositional effects on the removal mechanism and performance. More importantly, the reduced product Cr(III) was concurrently removed via precipitation and adsorption onto the MoS2 nanosheets, which could avoid the additional pH-elevation step that is typically needed in the conventional treatment. The unique 2D flake-like structure of MoS2 nanosheets enabled the formation of aligned and ion-accessible nanochannels, where Cr(VI) species were accommodated, reduced and sequestered. The irreversible shrinking of the nanochannels under drying modified the interior of the layer-stacked structure into confined compartments preventing the release and re-oxidation of the immobilized Cr(III). The compiled results highlight the effects of MoS2 composition and structure on the Cr removal efficiency and mechanism, which has substantial implications on future studies tailoring these unique features of 2D nanomaterials for various remediation scenarios.

Tuning the polymer thermal conductivity through structural modification induced by MoS2 bilayers.

The present work refers to a physical and structural study of nanoconfined polymers in polymer-MoS2 nanocomposites as a function of MoS2-MoS2 interlayer distance. We applied reverse nonequilibrium molecular dynamics (RNEMD) simulations to investigate the thermal conductivity (λ) of polyamide oligomers confined by MoS2 bilayers. The results of this study indicate that thermal conductivity of polymer can be considerably enhanced when polymer chains are confined by MoS2 sheets, this behavior is more pronounced by charged surfaces. The presence of MoS2 surfaces leads to elongation as well as preferential alignment of polymer chains parallel to the MoS2 surfaces, which in turn results in higher order and denser packing of polymer content and hence larger thermal conductivity in comparison to the bulk polymer. Additionally, the analysis of the number of hydrogen bonds (HBs) in confined polymer chains suggests that a combined effect of the mentioned structural modification and enlarged values of HBs may cooperatively contribute to high polymer thermal conductivity, facilitating phonon transport. The results reported here suggest a significant way to design confined polymer-MoS2 composites for significantly improving thermal conductivity for a wide variety of applications.

High-efficiency adsorption of elemental mercury from flue gas by K-intercalated 1T&2H MoS2

Alkali metal K is widely present in the earth's crust (the seventh abundant element), which can improve the activity and stability of the adsorbent. This study explored a simple calcination method, using the intercalation of K ions, successfully partially transformed commercial molybdenum disulfide (2H-MoS2) into 1T-MoS2, and used it for the adsorption of Hg0 in the flue gas. The experimental results showed that when the K ratio was 2:1(MK-3), the removal rate of Hg0 can reach 90.5 in a wide temperature range. Compared with 2H-MoS2, the mercury removal efficiency of MK-3 was increased by about 40%. After long-term and cycles experiments, the mercury removal efficiency of the MK-3 remained largely unchanged. In the simulated flue gas experiment, HCl could promote the mercury removal efficiency of sample MK-3, SO2 had no obvious effect on the mercury removal efficiency of sample MK-3, while SO2 and low concentration NO have no obvious effect on the mercury removal efficiency of the sample. It was found that during the intercalation of K ions, the interlayer spacing of MK-3 increased, and holes and cracks appeared on the base surface, which made it possible for Hg0 to enter the MoS2 interlayer and adsorb, thereby expanded the adsorption space of Hg0. DFT simulations showed that 1T-MoS2 significantly improves the surface activity of the adsorbent, thereby enhancing the stability of the sample to adsorb Hg0. Therefore, K intercalated in MoS2 can provide a promising method to capture Hg0 in coal-fired flue gas.

Self-assembled MoS2/C nanoflowers with expanded interlayer spacing as a high-performance anode for sodium ion batteries

Two-dimensional (2D) MoS2 nanomaterials have been extensively studied due to their special structure and high theoretical capacity, but it is still a huge challenge to improve its cycle stability and achieve superior fast charge and discharge performance. Herein, a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS2 nanoflower (MoS2/C NF) with expanded interlayer spacing via embedding a carbon layer into the interlayer. The carbon layer in the MoS2 interlayer can speed the transfer of electrons, while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process. Therefore, MoS2/C NF electrode exhibits exceptional rate performance (318.2 and 302.3 mA·h·g−1 at 5.0 and 10.0 A·g−1, respectively) and extraordinary cycle durability (98.8% retention after 300 cycles at a current density of 1.0 A·g−1). This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.

Designing Efficient MoS2/g‐C3N4 Hybrid Photocatalysts by Regulating the Interlayer Spacing of MoS2

Abstractg‐C3N4 as an appealing photocatalyst has received much attention due to its abundance, nontoxicity, and unique photoelectric properties. However, bare g‐C3N4 usually suffers from restricted light absorbance and serious carriers recombination. The key issue of boosting the photocatalytic performance of the g‐C3N4 lies in constructing hybrids for better optical and electrical effects. Here, the MoS2 with different interlayer spacing is integrated with g‐C3N4 via calcination and hydrothermal methods to form the high‐performance MoS2/g‐C3N4 hybrid photocatalyst. Optimized energy‐band alignment with g‐C3N4 is realized through regulating the interlayer spacing of MoS2, achieving improved carriers separation efficiency. In addition, the broadband absorption and rich active sites are also achieved here. As a result, the rationally designed MoS2/g‐C3N4 composite (the MoS2 interlayer spacing: 1.02 nm) exhibits the dominant photocatalytic performance (hydrogen production rate: 1281 μmol/h/g). This work opens a new road to realize a proper energy‐band alignment with g‐C3N4 for high performance photocatalytic activity.

Structural Properties and Electrical Characteristics of p-n Junctions Based on Kesterite Cu2ZnSnS4 Layers for Thin-Film Solar Cells

In the present study, we provide useful data related to one of the most promising materials in thin-film solar cell technologies: Cu2ZnSnS4 (CZTS) kesterite structures. Sol-gel spin coating and chemical bath deposition methods were used to fabricate and further investigate Mo/CZTS/CdS/ZnO/AZO heterostructures. In order to examine the crystal structure of the samples, Raman scattering measurements using two excitation wavelengths (514.5 nm and 785 nm) were performed. Three Raman bands related to CZTS were found, as well as one that had its origin in CdS. By using laser ablation and performing Raman spectroscopy on these modified samples, it was shown that during the manufacturing process a MoS2 interlayer was formed between the CZTS and Mo layers. Our method proved that the CZTS layer in a multilayer device structure fabricated by solution-based methods can be decomposed, and thus a detailed analysis of the layer can be performed. Subsequently, current-voltage curves were investigated in terms of the essential electrical properties of glass/Mo/p-CZTS/n-CdS/ZnO/AZO junctions and occurring current transport mechanisms. Finally, AFM data were acquired to study the surface topography of the studied samples. The images showed that these surfaces had a uniform grain structure.

Effect of MoS2 interlayer on performances of copper-barium-tin-sulfur thin film solar cells via theoretical simulation

Cu2BaSn(S,Se)4 (CBTSSe) solar cells are emerging photovoltaic devices due to their high theoretical efficiencies of ~31%, environment-friendly and earth-abundant composition, low density of non-recombination defects, and so on. However, the record efficiency of CBTSSe solar cell is only 5.2%, showing the importance of studying their performance via numerical analysis to further enhance their practical efficiencies. In this paper, the effect of absorber and buffer layers on performances of Cu2BaSnS4 (CBTS) solar cells are firstly systematically studied via the SCAPS-1D software to provide a platform for the study of the effect of MoS2 interlayer on the performances of CBTS solar cells. The highest PCE of CBTS solar cell with a 30 nm CdS buffer layer is 11.87%. The PCE of CBTS solar cell with a 0.8 μm CBTS absorb layer is 12.51%, indicating that the CBTS solar cell is a potential low-cost solar cell due to its large optical absorption coefficient (α > 104 cm−1). The efficiency of CBTS solar cell is improved to 16.47% when the carrier concentration of CBTS is 1016 cm−3. The relationship between the performance of solar cell and the band gap, thickness, donor concentration, acceptor concentration of MoS2 interlayer is systematically investigated on the basis of the optimized efficiency. It is found that MoS2 interlayer plays an important role in the performance of CBTS solar cell. The p-type MoS2 has a beneficial effect on the efficiency improvement while the n-type MoS2 has a negative effect on the efficiency enhancement. The highest PCE of CBTS solar cell is as high as 18.28% when the thickness and the acceptor concentration of MoS2 are 4 nm and 1019 cm−3, respectively. Our simulation result provides a promising research direction to further improve the actual efficiency of the CBTS solar cell.

Tuning the kinetics of zinc ion in MoS2 by polyaniline intercalation

Aqueous rechargeable zinc ion batteries (ARZIBs) are one of the promising electrochemical energy storage devices to overcome the worldwide energy challenge. However, the development of a suitable cathode with high energy/power densities and long cycle-life for ARZIBs is still a challenge. Here, a molybdenum disulfide/polyaniline (MoS2/PANI) hybrid with an inter-overlapped heterostructure is firstly explored as a superior cathode of ARZIBs. Its zinc intercalation chemistry is studied by combining means of ex-situ X-ray diffraction, ex-situ Raman, electrochemical analysis and density functional theory calculations. The results suggest an appropriate amount of PANI intercalation into MoS2 interlayer boosts the Zn2+ transport by expanding the interlayer spacing of MoS2 host and partially shielding the electrostatic interactions between Zn2+ and MoS2 host. Also, it enhances the charge transfer efficiency via reducing the bandgap between the conduction bands and valence bands of MoS2. As a result, the MoS2/PANI hybrid delivers a high reversible capacity of 106.5 mAh g − 1 at a current density of 1.0 A g−1 and retains 86% capacity after 1000 cycles.

Sandwich-Like Heterostructures of MoS2 /Graphene with Enlarged Interlayer Spacing and Enhanced Hydrophilicity as High-Performance Cathodes for Aqueous Zinc-Ion Batteries.

Layered materials have great potential as cathodes for aqueous zinc-ion batteries (AZIBs) because of their facile 2D Zn2+ transport channels; however, either low capacity or poor cycling stability limits their practical applications. Herein, two classical layered materials are innovatively combined by intercalating graphene into MoS2 gallery, which results in significantly enlarged MoS2 interlayers (from 0.62 to 1.16nm) and enhanced hydrophilicity. The sandwich-structured MoS2 /graphene nanosheets self-assemble into a flower-like architecture that facilitates Zn-ion diffusion, promotes electrolyte infiltration, and ensures high structural stability. Therefore, this novel MoS2 /graphene nanocomposite exhibits exceptional high-rate capability (285.4mA h g-1 at 0.05 A g-1 with 141.6mA h g-1 at 5 A g-1 ) and long-term cycling stability (88.2% capacity retention after 1800 cycles). The superior Zn2+ migration kinetics and desirable pseudocapacitive behaviors are confirmed by electrochemical measurements and density functional theory computations. The energy storage mechanism regarding the highly reversible phase transition between 2H- and 1T-MoS2 upon Zn-ion insertion/extraction is elucidated through ex situ investigations. As a proof of concept, a flexible quasi-solid-state zinc-ion battery employing the MoS2 /graphene cathode demonstrates great stability under different bending conditions. This study paves a new direction for the design and on-going development of 2D materials as high-performance cathodes for AZIBs.

Self-Assembled MoS2/ssDNA Nanostructures for the Capacitive Aptasensing of Acetamiprid Insecticide

The aim of this work is to detect acetamiprid using electrochemical capacitance spectroscopy, which is widely used as a pesticide in agriculture and is harmful to humans. We have designed aptasensing platform based on the adsorption of a DNA aptamer on lipoic acid-modified MoS2 nano-sheets. The biosensor takes advantage of the high affinity of single-stranded DNA sequences to MoS2 nano-sheets. The stability of DNA on MoS2 nano-sheets is assured by covalent attachment to lipoic acid that forms self-assembled layer on MoS2 surface. The biosensor exhibits excellent capacitance performances owing to its large effective surface area making it interesting material for capacitive transduction system. The impedance-derived capacitance varies with the increasing concentrations of acetamiprid that can be attributed to the aptamer desorption from the MoS2 nanosheets facilitating ion diffusion into MoS2 interlayers. The developed device showed high analytical performances for acetamiprid detection on electrochemical impedance spectroscopy EIS- derived capacitance variation and high selectivity toward the target in presence of other pesticides. Real sample analysis of food stuff such as tomatoes is demonstrated which open the way to their use for monitoring of food contaminants by tailoring the aptamer.

Melamine Foam Derived 2H/1T MoS2 as Flexible Interlayer with Efficient Polysulfides Trapping and Fast Li+ Diffusion to Stabilize Li-S Batteries.

Lithium-sulfur (Li-S) batteries featuring high-energy densities are identified as a hopeful energy storage system but are strongly impeded by shuttle effect and sluggish redox chemistry of sulfur cathodes. Herein, annealed melamine foam loaded 2H/1T MoS2 (CF@2H/1T MoS2) is prepared as a multifunctional interlayer to inhibit the shuttle effect, improve redox kinetics, and reduce the charge-discharge polarization of Li-S batteries. The CF@2H/1T MoS2 becomes fragmented structures after assembling the cell, which not only benefits to adsorb and catalyze LiPSs but also to significantly buffer the volume expansion due to a large number of gaps between fragmented structures. Meanwhile, the batteries based on CF@2H/1T MoS2 interlayer delivers high areal capacity of 5.1 mAh cm-2 under high sulfur mass loading of 7.6 mg cm-2 at 0.2 C. Importantly, the experiments of in situ Raman spectra demonstrate that the CF@2H/1T MoS2 can obviously inhibit the shuttle effect by effectively adsorbing and catalyzing LiPSs. This novel design idea and low-cost melamine foam raw material open up a new way for the application of high-energy density Li-S batteries.

Tuning interlayer spacing of MoS2 for enhanced hydrogen evolution reaction

The MoS2 structure engineering including hybrid structure construction and material self-optimization (edge sites improvement and phase transition), is a potential solution to boost photocatalytic hydrogen evolution reaction (HER) performance. Among the influence factors to MoS2 structure, the interlayer distance, which is a significant and non-ignorable parameter, plays a momentous role in tuning the photoelectric property and photocatalytic activity of MoS2. Here, we prepare MoS2 with different interlayer distances, and explore the corresponding optical and electrical properties. As the MoS2 interlayer spacing expands, the MoS2-1.12 (interlayer spacing 1.12 nm) is equipped with optimal light absorption ability, broadened energy band structure, high carrier mobility, and good electron transfer performance, compared to the MoS2-0.87 (interlayer spacing 0.87 nm) and MoS2-0.62 (interlayer spacing 0.62 nm). Consequently, the sample MoS2-1.12 possesses better HER performance (hydrogen production rate 311.28 μmol/g/h) than the MoS2-0.87 and MoS2-0.62. In addition, the MoS2 @Au core-shell structure with optimal interlayer distance is designed to further enhance the HER ability, and the H2 production rate of the MoS2-1.12@Au (773.4 μmol/g/h) is 2.48 times than that of the MoS2-1.12. The remarkable enhancement originates from the additional plasmonic Au nanoparticles. These results are significant for developing promising MoS2-based photocatalysts in the field of photocatalytic HER.

Modulation of MoS2 interlayer dynamics by in situ N-doped carbon intercalation for high-rate sodium-ion half/full batteries.

In comparison with lithium-ion batteries, sodium-ion batteries (SIBs) have been proposed as an alternative for large-scale energy storage. However, finding an anode material that can overcome the sluggish electrochemical reaction kinetics and fast capacity fading caused by large volume expansion during cycling is problematic. In this study, the intercalation technique for nitrogen-doped carbon layers is implemented for the molybdenum disulfide (MoS2/NC) structure to improve the rate and cycling stability of SIBs by increasing the diffusion rate of sodium ions and mitigating excessive volume structural expansion. The as-synthesized MoS2/NC anode has a high discharge specific capacity of 546 mA h g-1 at 1 A g-1 after 160 cycles, as well as a high rate and stable cycle performance of 406 mA h g-1 at 10 A g-1 after 1000 cycles. Upon coupling with a high-voltage Na3V2(PO4)2O2F cathode, the sodium-ion full battery displays high specific energies of 78.57 W h kg-1 and 49.70 W h kg-1 at specific powers of 193.76 W kg-1 and 3756.80 W kg-1, respectively, with commercialization potential demonstrated.

Electrochemical lithium storage performance of three-dimensional foam-like biocarbon/MoS2 composites

Abstract Molybdenum disulfide (MoS2) was loaded on biocarbon using waste camellia dregs (CDs) as the carbon source, which was further coated with dopamine hydrochloride to construct biocarbon/MoS2 electrode composites. The electrochemical lithium storage performance of the composites with different MoS2 contents was investigated. SEM results demonstrated that the composite had a three-dimensional foam-like structure with MoS2 as the interlayer. XRD and HRTEM tests revealed that MoS2 interlayer spacing in the composite was expanded. XPS analysis showed that new Mo—N bonds were formed in the active material. The electrochemical tests showed that the composite with a MoS2 content of 63% had a high initial specific capacity of 1434 mA·h/g at a current density of 100 mA/g. After a long cycle at a high current, it also showed good cycling stability and the capacity retention was nearly 100%. In addition, it had good lithium ion deintercalation ability in the electrochemical kinetics test.

Enhanced Spin Seebeck Thermopower in Pt/Holey MoS2/Y3Fe5O12 Hybrid Structure.

We first observed the spin-to-charge conversion due to both the inverse Rashba-Edelstein effect (IREE) and inverse spin-Hall effect in a holey multilayer molybdenum disulfide (MoS2) intermediate layer in a Pt/YIG structure via LSSE measurements under nonequilibrium magnetization. We found an enhancement of approximately 238%, 307%, and 290% in the longitudinal spin Seebeck effect (LSSE) voltage, spin-to-charge current, and thermoelectric (TE) power factor, respectively, compared with the monolayer MoS2 interlayer in a Pt/YIG structure. Such an enhancement in the LSSE performance of Pt/holey MoS2/YIG can be explained by the improvement of spin accumulation in the Pt layer by induced spin fluctuation as well as increased additional spin-to-charge conversion due to in-plane IREE. Our findings represent a significant achievement in the understanding of spin transport in atomically thin MoS2 interlayers and pave the way toward large-area TE energy-harvesting devices in two-dimensional transition metal dichalcogenide materials.

Multifunctional Cathodic Interlayer with Polysulfide Immobilization Mechanism for High‐Performance Li‐S Batteries

AbstractA highly efficient multifunctional polyvinylidene fluoride//carbon‐molybdenum disulfide (PVDF//C‐MoS2) interlayer is developed by direct deposition on sulfur cathode through facile slide coating method for Li−S batteries. The as‐developed PVDF//C–MoS2 interlayer exhibits the polysulfide adsorption and trapping capabilities, which reduces the shuttling effects and also slows down the self‐discharge in Li−S batteries. The first composite layer (C‐MoS2) on the cathode maximizes the level of lithium polysulfide adsorption owing to the strong dipolar interaction of Mo−S on the polarized surface of polysulfide species. Moreover, the PVDF layer physically traps/capture the remaining polysulfide species with its interconnected microstructure for the reutilization as active material in the cathode. The Li−S batteries based on interlayers deliver the discharge capacity of 1086 mAh g−1 at 1 C with 3.0 mg cm−2 sulfur loading and show capacity decay of 0.04 % per cycle after 1500 cycles. In contrast, the Li−S batteries without interlayer merely maintain the discharge capacities of 423 mAh g−1 at 1 C with 3.0 mg cm−2 sulfur loading and show severe capacity decay (0.12 %) after 505 cycles. The Li−S batteries also depict the remarkable cyclic performances with as‐developed interlayer for high sulfur loading cathodes and efficiently slowdowns the self‐discharge even after resting for a long time.

Spin-Valve Effect in Fe3GeTe2/MoS2/Fe3GeTe2 van der Waals Heterostructures.

The van der Waals (vdW) materials offer an opportunity to build all-two-dimensional (all-2D) spintronic devices with high-quality interfaces regardless of the lattice mismatch. Here, we report on an all-2D vertical spin valve that combines a typical layered semiconductor MoS2 with vdW ferromagnetic metal Fe3GeTe2 (FGT) flakes. The linear current-voltage curves illustrate that Ohmic contacts are formed in FGT/MoS2 interfaces, while the temperature dependence of the junction resistance further demonstrates that the MoS2 interlayer acts as a conducting layer instead of a tunneling layer. In addition, the magnitude of the magnetoresistance (MR) of 3.1% at 10 K is observed, which is around 8 times larger than that of the reported spin valves based on MoS2 sandwiched by conventional ferromagnetic electrodes. The MR decreasing monotonically with increasing temperature follows the Bloch's law. As the bias current decreases exponentially, the MR increases linearly up to a maximum value of 4.1%. Our results reveal the potential opportunities of vdW heterostructures for developing novel spintronic devices.

Performance enhancement of graphene/porous Si solar cells by employing layer-controlled MoS2

Porous Si (PSi) is attractive due to its high light absorption originating from the large surface to volume ratio and additional benefits such as surface passivation and texturization effects, thereby possibly improving Si-based solar cells. Here, we first employ (trifluoromethanesulfonyl)-amide (TFSA)-doped graphene (TFSA-GR) transparent conductive electrode and MoS2 interlayer in GR/PSi solar cells. The photovoltaic parameters of the cell strongly depend on the doping concentration (nD) of the TFSA- GR and the number of layers (Ln) of the MoS2. In particular, the MoS2 interlayer well adjusts the band alignment between the TFSA-GR and PSi, thereby facilitating the separation/collection of carriers, resulting in the enhancement of the photovoltaic parameters. TiOx passivation is also used for reducing the recombination loss at the back surface. The TFSA-GR/MoS2/PSi/Si/TiOx solar cells show maximum power conversion efficiency (PCE) of 13.18% at nD = 20 mM and Ln = 4. While the PCE is monitored under 20–22 °C and 40% humidity for 30 days, it shows only a 15% loss, excellent long-term stability.