Superior Transport Properties Research Articles

Seed-Assisted Hydrothermal Synthesis of Monodispersed Au@C Core–Shell Nanostructures for Enhancing Thermal Diffusivity of Water-Based Nanofluids

Au@C core–shell nanostructures (Au@C-NS) were synthesized through a low-temperature seed-assisted hydrothermal approach using glucose as carbon source. The material characterization and chemical analysis confirm that the synthesis method allows to obtain uniform core–shell nanostructures constituted by a crystalline metal core and an amorphous carbon shell. Depending on the synthesis conditions, their average size ranges from 146 nm to 342 nm with relative standard deviation as low as 7 %. It is proposed that the characteristic monodispersity results due to a high nucleation rate of the carbon phase at the liquid–solid interface. The obtained monodisperse Au@C-NS were used to prepare water-based nanofluids with superior heat transport properties. The thermal lens analysis shows that the thermal diffusivity of Au@C nanofluids is 9.5 % and 31.3 % higher than their Au nanofluids counterparts and pure water, respectively, at particle concentration of 285 × 1011 ml−1. Phonon-related interactions at the metal cores and carbon shells interfaces are proposed as the heat transport mechanism behind the thermal diffusivity enhancement of the Au@C water-based nanofluids.

Jamming Giant Molecules at Interface in Organic Photovoltaics to Improve Performance and Stability.

A novel approach for depositing the giant molecule acceptor (GMA) at the donor-acceptor interface to enhance the efficiency and stability of organic photovoltaic (OPV) devices through a designed interface-enhanced layer-by-layer device fabrication protocol is proposed. The giant molecule acceptor DQx-Ph is mixed with the polymer donor in the bottom layer to form a polymer donor fibril phase and a mixed phase, followed by subsequent deposition of the main acceptor L8-BO. The L8-BO solution swells the bottom layer and alters the localized morphology of the mixing phase, introducing L8-BO fibrillar crystallization and pushing DQx-Ph giant molecules outwards to the fibril interfaces. Through this approach, the localized morphology and optoelectronic property of the bulk heterojunction are optimized. This configuration maintains the superior transport properties of L8-BO while integrating the high open-circuit voltage characteristics of DQx-Ph. Additionally, exciton dissociation and charge generation are simultaneously enhanced, with suppressed energy losses. A power conversion efficiency of 19.9% with improved operational stability is achieved, underscoring the importance of GMA interface jamming in advancing OPV technology. This study provides new insights into the development of ancillary OPV materials to overcome the critical limitations in OPV, revealing innovative approaches for photovoltaic technologies.

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky‐cation‐based 2D structures often exhibit poor charge transport and are prone to formation of charge‐extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16‐cm2 single cell and 21.0% in a 24.8‐cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA‐based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1‐Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules.

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky-cation-based 2D structures often exhibit poor charge transport and are prone to formation of charge-extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16-cm2 single cell and 21.0% in a 24.8-cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA-based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1-Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Anionic and cationic co-doping to enhance the oxygen transport property of Bi0.5Sr0.5FeO3-δ as a high-performance air electrode for reversible solid oxide cells

Reversible solid oxide cells (RSOCs) have attracted considerable interest due to their efficient energy conversion. However, the low catalytic activity of air electrodes limits the application of RSOCs. Bi0.5Sr0.5Fe0.9Ta0.1O3-δ developed in our previous work exhibits a comparatively desirable performance and is expected to be further optimized. Herein, a novel strategy of anionic F and cationic Ta co-doped Bi0.5Sr0.5Fe0.9Ta0.1O3-δ-xFx (x = 0, 0.05, 0.10, 0.15, denoted as, BSFTF0, BSFTF5, BSFTF10, BSFTF15) materials are obtained to enhance the oxygen transport property of Bi0.5Sr0.5FeO3-δ for RSOCs. The polarization resistance (Rp) of BSFTF10 (0.017 Ω cm2) decreases by 66 % compared with that of BSFTF0 (0.051 Ω cm2) at 800 °C. In fuel cell mode, the single cell with BSTF10 reaches the maximum power density of 908 mW cm−2, which is approximately 72 % higher than the only Ta-doped BSFTF0 (527 mW cm−2) at 800 °C. In electrolysis mode, the single cell with BSFTF10 exhibits a high electrolysis current density of 1679 mA cm−2, indicating an approximately 90 % increase compared to that of BSFTF0 at 800 °C and 1.5 V with 70 % CO2-30 % CO feed gas. The bulk chemical diffusion (Dchem) of BSFTF10 is up to 5.12 × 10−4 cm2 s−1, which is 4.3 times higher than that of BSFTF0. The superior oxygen transport property of BSFTF10 is attributed to the high electronegativity of F− (4.0) and low electronegativity of Ta5+(1.8), which may weaken the chemical bonding between B-site ions and O2−, generating more oxygen vacancies and accelerating the rate of oxygen transfer. The results indicate that F and Ta co-doping is an effective strategy to develop a highly catalytically active air electrode for RSOCs featuring oxygen transport properties.

Determination of electron‐hole pair creation energy in Cd0.9Zn0.1Te0.98Se0.02 quaternary semiconductor for room‐temperature gamma‐ray detection

AbstractWe report the first‐time measurement of the electron‐hole pair (ehp) creation energy (Wehp) in novel Cd0.9Zn0.1Te0.98Se0.02 (CZTS) quaternary semiconductor. CZTS in single crystalline form is poised to be the future of large‐volume room‐temperature gamma‐ray detectors due to its excellent compositional homogeneity with highly reduced defects, high‐Z (atomic number) constituents, wide bandgap (1.6 eV), and superior charge transport properties. Despite a great deal of study of the material and device properties since its inception, the Wehp in CZTS has not been measured experimentally. Accurate determination of Wehp is essential for calibration of the spectrometer and other theoretical calculations. In this study we have used an absolute calibration approach, which is based on an iterative approach that yields the Wehp as the best‐fit parameter. Using a 241Am alpha emitting radioisotope and a planar CZTS detector, the Wehp in CZTS was calculated to be 4.47 eV. The obtained value has been validated by accurately predicting the peak energy for gamma rays emitted by a 137Cs source and read by a CZTS detector with different dimensions. The dependences of the calculated Wehp value on the detector dimensions, type of interaction, and effect of charge trapping are also discussed.

Impact of Structural Alterations from Chemical Doping on the Electrical Transport Properties of Conjugated Polymers.

Conjugated polymers (CPs) are widely used as conductive materials in various applications, with their conductive properties adjustable through chemical doping. While doping enhances the thermoelectric properties of CPs due to improved main-chain transport, overdoping can distort the polymer structure, increasing energy disorder and impeding intrinsic electrical transport. This study explored how different dopants affect the structural integrity and electrical transport properties of CPs. We found that dopants vary in their impact on CP structure, consequently altering their electrical transport capabilities. Specifically, ferric chloride (FeCl3)-doped indacenodithiophene-co-benzothiadiazole (IDTBT) shows superior electrical transport properties to triethyloxonium hexachloroantimonate (OA)-doped IDTBT due to enhanced backbone planarity and rigidity, which facilitate carrier transport and lower energetic disorder. These results highlight the critical role of dopant selection in optimizing CPs for advanced applications, suggesting that strategic dopant choices can significantly refine the charge transport characteristics of CPs, paving the way for their industrialization.

Nanoscale Graded Nitrogen-Doping of TiO2 via Pulsed Laser Deposition for Enhancing Charge Transfer in Perovskite Solar Cells.

An electron transport layer (ETL) for highly efficient perovskite solar cells (PSCs) should exhibit superior electrical transport properties and have its band levels aligned with interfacing layers to ensure efficient extraction of photo-generated carriers. Nitrogen-doped TiO2 (TiO2:N) is considered a promising ETL because it offers higher electrical conductivity compared to conventional ETLs made from spray-pyrolyzed TiO2. However, the application of highly doped TiO2:N in PSCs is often limited by the misalignment of energy band levels with adjacent layers and reduced optical transparency. In this study, a novel approach is introduced to enhance the charge transport characteristics and accurately align the electronic band alignment of TiO2:N layer through nanoscale doping level grading, achieved through the pulsed laser deposition (PLD) technique. The TiO2:N ETL with a graded doping profile can combine characteristics of both highly doped and lightly doped phases on each side. Furthermore, a nanoscale doping gradation, employing an ultrathin sub-layer structure with graded doping levels, creates a smoothly cascading band-level alignment that bridges the adjacent layers, enhancing the transport of photo-generated carriers. Consequently, this method leads to a substantial increase in the power conversion efficiency (PCE), exceeding 22%, which represents a relative improvement of 11% compared to traditional spray-pyrolyzed TiO2-based PSCs.

Mechanical Tuning of Fluorescence Lifetime and Bandgap in an Elastically Flexible Molecular Semiconductor Crystal.

Despite having superior transport properties, lack of mechanical flexibility is a major drawback of crystalline molecular semiconductors as compared to their polymer analogues. Here single crystals of an organic semiconductor are reported that are not only flexible but exhibit systematic tuning of bandgaps, fluorescence lifetime, and emission wavelengths upon elastically bending. Spatially resolved fluorescence lifetime imaging and confocal fluorescence microscopy reveals systematic trends in the lifetime decay across the bent crystal region along with shifts in the emission wavelength. From the outer arc to the inner arc of the bent crystal, a significant decrease in the lifetime of ≈1.9ns is observed, with a gradual bathochromic shift of ≈10nm in the emission wavelength. For the crystal having a bandgap of 2.73eV, the directional stress arising from bending leads to molecular reorientation effects and variations in the extent of intermolecular interactions- which are correlated to the lowering of bandgap and the evolution of the projected density of states. The systematic changes in the interactions quantified using electron density topological analysis in the compressed inner arc and elongated outer arc region are correlated to the non-radiative decay processes, thus rationalizing the tuning of fluorescence lifetime.

(Keynote) Light Driven H2 Generation in Pt-Tipped CdS Nanorods: Dependence on the Pt Size and CdS Rod Length

Colloidal quantum confined semiconductor-metal nano-heterostructures are a promising class of photocatalysts for solar energy conversion. In these photocatalysts, the semiconductor domain serves as the light absorber and the metal as the catalyst. Such photocatalysts combine the superior light absorption and charge transport properties of the semiconductor with the superior catalytic activity and selectivity of the metal. Furthermore, both domains can be independently tuned to enhance the photocatalytic performance of the heterostructure. Among various semiconductor/metal heterostructures, metal-tipped colloidal semiconductor nanorods have attracted extensive interest because they have been reported to have high quantum efficiencies of light driven H2 generation and their morphology can be systematically tuned. The overall light driven H2 generation process involves multiple elementary charge separation and recombination steps in the semiconductor and across the semiconductor/metal interface as well as proton-coupled electron transfer reactions at the catalytic center. The change of the semiconductor or metal domains can often have effects on multiple competing processes involved in the overall reaction. As a result of these complexities, the mechanisms for the morphological dependence of the observed H2 generation efficiencies are not fully understood, hindering the rational design of these photocatalysts. In this talk, we use Pt tipped CdS nanorods (CdS-Pt) as a model system to examine the effect of Pt size and CdS rod length on their light driven H2 generation efficiency. We show that increasing the Pt particle size increases the overall H2 generation quantum efficiency through both increasing the rate of electron transfer from the CdS to Pt and enhancing the efficiency of water/proton reduction; H2 generation efficiency increases at longer CdS rod length by suppression of charge recombination across the Pt/CdS interface. Furthermore, because of rapid trapping of valence band holes, multi-exciton states in CdS nanorods can be long lived, enabling efficient multi-electron transfer to the Pt. Our work demonstrates that through systematic in situ study of elementary processes involved in the overall H2 generation, it is possible to rationally design and improve semiconductor-metal hybrid photocatalysts.

Tellurium doped sulfurized polyacrylonitrile nanoflower for high-energy-density, long-lifespan sodium-sulfur batteries

Sodium-sulfur (Na−S) batteries are promising energy storage devices for large-scale applications due to their high-energy-density and abundant material reserve. However, the practical implementation of room temperature (RT) Na−S batteries faces challenges, including low-energy-density and limited lifespan, particularly attributed to the properties of sulfurized polyacrylonitrile (SPAN). In this study, we address these challenges by introducing tellurium doping into SPAN nanoflowers, enhancing their performance for Na−S batteries. The resulting material exhibits high sulfur loading as well as superior electron and ion transport properties, leading to enhanced redox kinetics and improved battery performance. The tellurium-doped SPAN nanoflower electrode delivers an exceptional composite capacity of 700 mAh g−1 at 0.1 C and demonstrates stable cycling over 2400 cycles with minimal capacity fade (0.01 % average fading rate). Even under challenging conditions (24.0 mg cm−2, E/S=5 mg μLS−1, N/P=2.1), the Na−S battery achieves a high areal capacity of 16.1 mAh cm−2, resulting in an impressive energy density of 340.9 Wh kg–1 based on cathode and anode. This work presents a promising approach to designing high-energy-density, long-lifespan RT Na−S batteries, with potential applications for other metal-sulfur battery systems.

New piperidinium surfactants with carbamate fragments as effective adjuvants in insecticide compositions based on imidacloprid.

Surfactants, particularly non-ionic ones, are widely used as adjuvants in pesticide formulations due to their ability to maintain pesticide effectiveness without changing solution properties, such as pH. While non-ionic surfactants are generally low-toxic, stable, and excellent dispersants with high solubilization capabilities, they may be less effective than cationic surfactants, which offer superior surface activity, transport properties, and antimicrobial action. This study investigates the efficacy of new piperidinium surfactants with carbamate fragments as adjuvants in insecticide formulations containing imidacloprid. The efficacy of these formulations is being assessed against greenhouse whitefly, a pest known to harm cultivated and ornamental flowering plants. The aggregation behavior of piperidinium surfactants containing carbamate fragments was investigated, and their wetting effect was evaluated. Synthesized surfactants have lower CMC values compared to their methylpiperidinium analogue. The effect of piperidinium surfactants on the insecticide concentration on the surface and inside tomato leaves was assessed using spectrophotometric methods. It was found that the introduction of piperidinium surfactants with carbamate fragment at a concentration of 0.1% wt. allows for decrease in lethal concentration of imidacloprid up to 10 times, thereby testifying the marked increase in the effectiveness of imidacloprid against the greenhouse whitefly insect pest (Trialeurodes vaporariorum). It was shown that the main factors responsible for the enhanced efficacy of the insecticide were the ability of the surfactant to increase the concentration of imidacloprid on the leaf surfaces and improve their penetration into the plant. The presented work employed a comprehensive approach, which significantly increases the generalizability of the results obtained and provides the ability to predict the effect and target selection of adjuvants. © 2024 Society of Chemical Industry.

CuInS2/Red Phosphorus Nanosheet Interleaved Heterostructures with Improved Interfacial Charge Transfer for Photoelectrochemical Aptasensing.

Accelerating the migration of interfacial carriers in heterojunctions is crucial for achieving highly sensitive photoelectrochemical (PEC) sensing. In this study, we developed three-dimensional (3D)/two-dimensional (2D) CuInS2/red phosphorus nanosheet (CuInS2/RP NS) n-n heterojunction functional materials with enhanced interfacial charge transfer capabilities for PEC sensing. The 3D CuInS2 serves as a conductive layer, providing excellent electronic conductivity and superior electron absorption and transport properties. In contrast, the ultrathin RP NS acts as a transport layer that enhances carrier mobility. The 3D/2D heterojunction ensures a large interface contact surface, shortening the carrier transport distance. A well-aligned band position generates a substantial built-in electric field, providing a significant driving force for efficient carrier separation and migration, thereby improving response sensitivity. A PEC aptamer sensor was constructed based on the synthesized heterostructure for ciprofloxacin detection. The detection limit of the CuInS2/RP NS aptamer sensor for ciprofloxacin is 2.03 × 10-15 mg·mL-1, with a linear range from 1.0 × 10-14 to 1.0 × 10-5 mg·mL-1. This work presents a strategy for enhancing the photoelectric response by modulating the interface structure of heterojunctions, thereby opening new prospects for the application of highly sensitive PEC sensors in antibiotic detection.

Decorating the Node of a Zirconium-Based Metal-Organic Framework to Tune Adsorption Behavior and Surface Permeation.

Surface barriers are commonly observed in nanoporous materials. Although researchers have explored methods to repair defects or create flawless crystals to mitigate surface barriers, these approaches may not always be practical or readily achievable in targeted metal-organic frameworks (MOFs). In our study, we propose an alternative approach focusing on the introduction of diverse ligands onto a MOF-808 node to finely adjust its adsorption and mass transport characteristics. Significantly, our findings indicate that while adsorption curves can be inferred based on the MOF's chemical composition and the probing molecule, surface permeabilities exhibit variations dependent on the specific probe utilized and the incorporated ligand. Our investigation, considering van der Waals forces exclusively between the adsorbate (e.g., n-hexane, propane, and benzene) and the adsorbent, revealed that augmenting these interactions can indeed improve surface permeation to a certain extent. Conversely, strong adsorption resulting from hydrogen bonding interactions, particularly with water in modified MOFs, led to compromised permeation within the MOF crystals. These outcomes provide valuable insights for the porous materials community and offer guidance in the development of adsorbents with enhanced affinity and superior mass transport properties for gases and vapors.

DFT+U investigation of electronic, optical, and thermoelectric properties of YAuX (X=Si or Ge or Sn) half-Heusler alloys

Half-heusler alloys are fascinating thermoelectric materials because they have superior mechanical and transport properties. In this study, we used dft+u calculations and the Boltztrap equation to examine the electronic, optical, and thermoelectric properties of YAuSi, YAuGe, and YAuSn half-heusler alloys. The DFT+U approach predicted band gaps of 1.2767 eV, 0.611 eV, and 1.5741 eV for YAuGe, YAUSn, and YAuSi, respectively. We also observed that all materials under consideration have a broad absorption spectrum ranging from 1 eV to 12 eV, with notable peaks in the visible and UV ranges. The obtained opto-electronic properties position the three alloys as promising candidates for photovoltaic applications. Finally, thermoelectric property calculations revealed that the figure of merit values for YAuSi, YAuGe, and YAuSn HH alloys were 0.730, 0.726, and 0.736 at 800 K, respectively suggesting the materials are also suitable candidates for application in the field of thermoelectricity

Polymer electrolyte fuel cell operating with nickel foam-based gas diffusion layers: A numerical investigation

Due to their outstanding structural, transport and electrical characteristics, nickel foams serve as excellent candidate materials for gas diffusion layers (GDLs) in polymer electrolyte fuel cells (PEFCs). In this work, a new three-dimensional PEFC model was developed to explore the local and global fuel cell performance with nickel foam-based GDLs. The fuel cell operating with nickel foam GDLs was shown to have, due to its superior mass and charge transport properties, higher oxygen and water concentration and current density compared to that operating with the conventional carbon fibre-based GDLs. The results show that the pumping power should be taken into account when optimising the dimensions of the flow channels and as such the net power density must be the criterion for optimisation. The optimal dimensions of the flow channels for the fuel cell operating with nickel foam based GDLs were found to be 0.25 mm for the channel height and 1 mm for the channel width; the maximum net power density with these dimensions was around 0.95 W/cm2 which is two times higher than that operating with carbon fibre based GDLs. All the results have been presented and critically discussed.

Multifunctional properties of carbon nanotube yarn/aerogel laminate composites

This work explores the multifunctional performance of scalable carbon nanotube (CNT) yarn laminate composites. Tensile, thermal, electrical, and electromagnetic interference (EMI) shielding properties are compared to state-of-the-art unidirectional IM7/5250-4 carbon fiber composite (CFRP). CNT laminates achieved a specific tensile modulus of 249.7 ± 22.3 GPa/(g/cm3), which is over double the specific modulus of the CFRP, while maintaining a specific tensile strength of 1.88 ± 0.17 GPa/(g/cm3) which is comparable to the CFRP. CNT yarn laminates demonstrated superior thermal transport properties, with in-plane thermal conductivity of 75.78 ± 14.3 W/mK, over 13 times higher than the CFRP. CNT yarn laminates were also superior in electrical conductivity, achieving a longitudinal conductivity of 5359 ± 417 S/cm and transverse conductivity of 36.87 ± 2.55 S/cm. This translated to superior EMI shielding properties, achieving over 100 dB in the X-band, which is nearly double that of the CFRP. Incorporating CNT aerogel interwoven between CNT yarns reduced the large property variance observed in the measurements, demonstrating a multifunctional material with tensile, thermal, electrical, and EMI properties superior to the CFRP, while potentially mitigating the scalability challenges inherent to CNT nanomaterials.

Interface Engineering of Substrate-Integrated Single-Crystal Perovskite Wafers for Sensitive X-Ray Detection.

Metal halide perovskite single crystals are emerging candidates for X-ray detection, however, it is challenging for growth of thickness-controlled single-crystal wafer on commercial backplanes, limiting their practical imaging application. Herein, integration of micrometer-thick methylammonium lead triiodide (MAPbI3) single-crystal wafer on indium tin oxide (ITO) substrates by methylamine (MA)-induced interface recrystallization is reported. Through selection of hole transport material with rich functional group, intimate interface contact with low trap density can be achieved, leading to superior carrier transport properties and homogeneous photoresponse. The as-fabricated X-ray detectors exhibit high sensitivity of 1.4×104 µC Gyair -1 cm-2 and low detection limit of 177 nGyair s-1, which are comparable to previous reports based on free-standing MAPbI3 bulk crystals. This work provides a feasible strategy for constructing substrate-integrated single-crystal perovskite wafers with controlled thickness, which may promote practical imaging application of perovskite X-ray detectors.

The design and preparation of NDI modified MOFs for high efficiency removal of MB and Cr(VI)

The naphthalene tetracarboxdiimide (NDI) modified NH2-UiO-66(Zr) and NH2-MIL-101(Cr) (NDI/UZr and NDI/MCr for short) metal organic frameworks (MOFs) materials with strong covalent bond OC–N–CO were designed and prepared by solvothermal method. The comprehensive physical and chemical properties of the materials were characterized, and the adsorption and photocatalytic properties of the materials were evaluated by using methylene blue (MB) and Cr(VI) in single and mixture system. When the initial concentration of MB was 50 mg·L−1, the photocatalytic degradation rate constant of NDI/MCr(2:1) was 10.3 and 13.8 times higher than that of NH2-MIL-101(Cr) and NDI/UZr(2:1), respectively. Additionally, NDI/MCr(2:1) exhibited 1.6 times higher reaction rate constant than that of NDI/UZr(2:1) for the removal of 10 mg∙L−1 Cr(VI). The enhanced adsorption and photocatalytic ability over NDI/MOFs were attributed to the MOFs larger specific surface area and wider spectral response, and NDI showed high electron affinity, superior charge carrier transport properties. Free radical and electron capture experiments indicated that h+, •O2−, and e− were the main active species in the NDI/MOFs system. Among them h+ and •O2− played an essential role in the removal of MB, while e− and •O2− contributed to the photocatalytic reduction of Cr(VI). The mechanism of the photocatalytic process was discussed in detail.

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS2/MoS2 Heterojunctions.

Two-dimensional transition metal dichalcogenides (2D TMDCs) are considered promising alternatives to Si as channel materials because of the possibility of retaining their superior electronic transport properties even at atomic body thicknesses. However, the realization of high-performance 2D TMDC field-effect transistors remains a challenge owing to Fermi-level pinning (FLP) caused by gap states and the inherent high Schottky barrier height (SBH) within the metal contact and channel layer. This study demonstrates that high-quality van der Waals (vdW) heterojunction-based contacts can be formed by depositing semimetallic TiS2 onto monolayer (ML) MoS2. After confirming the successful formation of a TiS2/ML MoS2 heterojunction, the contact properties of vdW semimetal TiS2 were thoroughly investigated. With clean interfaces of the TiS2/ML MoS2 heterojunctions, atomic-layer-deposited TiS2 can induce gap-state saturation and suppress FLP. Consequently, compared with conventional evaporated metal electrodes, the TiS2/ML MoS2 heterojunctions exhibit a lower SBH of 8.54 meV and better contact properties. This, in turn, substantially improves the overall performance of the device, including its on-current, subthreshold swing, and threshold voltage. Furthermore, we believe that our proposed strategy for vdW-based contact formation will contribute to the development of 2D materials used in next-generation electronics.