Heterostructure Composites Research Articles

Investigation of Ceria based Heterostructure Composite Mixed Matrix Membrane with Polybenzimidazole for Polymer Electrolyte Fuel Cell Application at High Temperature

In recent years Ceria based heterostructure composites are considered as one of the highest performing solid state ionic conductors, therefore we wanted to leverage the benefits of using these materials for high temperature Proton Exchange Membrane Fuel Cells (PEMFCs). In this study a Polybenzimidazole (PBI)/Ceria carbonate CHC (Ceria based heterostructure composite) membrane was prepared by drop casting method and tested as an electrolyte for a high temperature H2/Air PEMFC application in anhydrous condition. Inorganic composite of ceria and alkali metal carbonates (Li2CO3, Na2CO3) was prepared by solid state route to obtain Ceria carbonate CHC. X-Ray diffraction (XRD) study confirmed the formation of the heterostructure and their successful incorporation into the PBI membranes. Homogeneity of fillers inside the membrane was further verified by Energy Dispersive X-Ray Analysis (EDAX) and Scanning Electron Microscopy (SEM). 5wt% of inorganic powder induced inside the PBI fillers reduced the phosphoric acid uptake of composite membrane (∼17% less) compared to pristine PBI membrane, which ultimately resulted into a lower swelling and dimensional change of the composite membrane. Thermal robustness of the phosphoric acid doped composite and pristine PBI membranes was investigated by thermogravimetric analysis (TGA) which showed that the prepared membranes were gone under a less than 10% reduction in weight up till 200ºC, ensuring their validity of application in high temp PEM fuel cells. The added inorganic functionalities resulted in a slight increase in the proton conductivity of PA doped composite PBI membranes i.e., 42.3 mS cm-1 at 180 ºC while for pristine PBI membrane it is 36 mS cm-1 at same temperature. A single cell with composite PBI membranes outperformed a pristine PBI membrane resulted into a ∼120% higher peak power density i.e., 320.88 mW cm-2. The composite membrane also displayed the excellent durability and showed a less than 10-4 mV/h degradation in cell potential till 180 ºC.

Improved polarization loss and impedance matching induced by carbon paper-based magnetic heterostructured composites for lightweight and strong microwave absorption

Improved polarization loss and impedance matching induced by carbon paper-based magnetic heterostructured composites for lightweight and strong microwave absorption

Ag-Mediated Growth of Au/Ag-Cu Ternary Heterostructures for Selective Electrochemical CO2 Reduction.

Copper (Cu)-based nanocatalysts play crucial roles in the electrochemical CO2 reduction reaction (ECO2RR) for sustainable energy resources. Particularly, Cu-based nanostructures incorporating Au and Ag are promising, offering enhanced activity, selectivity, and stability. However, precise control over the structure and composition of heterostructures remains challenging, hindering the development of highly efficient catalysts. Herein, we present a silver (Ag) transition-layer-mediated approach to synthesize ternary heterostructures with two specific morphologies, namely, Au/Ag-Cu-side and Au/Ag-Cu-tip, which exhibit different Ag-Cu interface epitaxial patterns. The two heterostructures achieve high C2 product selectivity in ECO2RR. Especially, the Au/Ag-Cu-side structure achieves 50.3% C2 selectivity with 35.5% ethanol, while the tip structure shows higher ethylene selectivity. Our study reveals the impact of the Ag layer in directing deposition sites on heterostructure growth and further facilitating the design of multicomponent Cu-based catalysts with enhanced structural integrity and ECO2RR performance.

Layered bismuthene forming the interfacial pathway for rapid charge transfer in CuNb13O33/g-C3N5 photocatalyst for enhancing ciprofloxacin degradation

The objective of the present research was to examine the usefulness of the photocatalytic degradation process in removing the ciprofloxacin drug from wastewater, which is difficult to remove from waterbodies. To tackle this difficulty, a ternary copper niobium oxide/carbon nitride/layered bismuthene heterostructure (CuNb13O33/g-C3N5-L-Bi) composite was developed by an intuitive solvothermal process. layered bismuthene (L-Bi) was prepared using a unique ball milling approach. According to the results of the characterization, adding L-Bi and g-C3N5 with a low band gap to the original band structure of CuNb13O33 makes it more efficient. After 120 min of irradiation, the modified CuNb13O33/g-C3N5-L-Bi sample significantly improved ciprofloxacin degradation, resulting in a degradation rate of 98 %. In addition, the impact of the catalyst that has been created on the removal of ciprofloxacin at various pH, catalyst dosages, and scavengers was also examined, demonstrating the catalyst’s suitability for purifying natural water environments. A detailed study of the steps used to break down ciprofloxacin has shown that many active species are involved, with a focus on the important roles played by reactive oxidative species (ROS). Thus, this study introduces a novel combination of layered bismuthene photocatalysts for environmentally friendly degradation of antibiotics.

Phosphorus doping heterostructure La(OH)3@CuO @NF as an advanced electrocatalyst for the oxygen evolution reaction

Due to the prevailing energy shortages, the pursuit of new alternative energy sources is becoming increasingly urgent. Hydrogen production through water electrolysis has emerged as a crucial method. However, the sluggish four-electron reaction in the oxygen evolution reaction (OER) remains the primary rate-limiting step. In this study, we synthesized a heterostructure La(OH)3@CuO-P material on the nickel foam (NF) substrate. The experimental results demonstrate that after phosphating treatment, the heterostructure La(OH)3@CuO-P exhibits exceptional catalytic performance with only 215 mV overpotential, a Tafel slope value of 79.36 mV/dec, and a bilayer capacitance of 39.02 mF/cm2 at a current density of 10 mA/cm2 for OER in a 1 M KOH solution. These values are significantly superior compared to those obtained using heterostructure La(OH)3@CuO alone which showed an overpotential value of 365 mV at a current density of 10 mA/cm2. Moreover, during cyclic voltammetry testing for up to 500 cycles, La(OH)3@CuO-P also demonstrates relatively stable performance. Analyses suggest that composite heterostructure effectively addresses issues such as insufficient conductivity of La(OH)3 and monomer aggregation tendency for CuO while maintaining excellent properties for each component. By incorporating P atoms as dopants, the interaction between La, Cu, and P atoms not only facilitates fine-tuning of the electronic structure and optimization of the adsorption free energy (-OH), but also promotes an increase in catalytic active sites through sample size reduction, thereby further augmenting the performance of the OER.

Enhanced dopamine detection using Ti3C2Tx/rGO/Pt ternary composite synthesized via microwave-assisted hydrothermal method

A novel electrochemical sensing platform for dopamine (DA) detection was developed by fabricating the ternary composite of Ti3C2Tx MXene (M) and reduced graphene oxide (rGO) with platinum nanoparticles (Pt NPs) through microwave-assisted hydrothermal heating. The exceptional electrical conductivity and rich surface chemistry of MXene provide abundant active catalytic sites for electrochemical reactions, while the large surface area of rGO facilitates ion and electron pathways. The integration of rGO in the MXene sheet, forming MXene-rGO (M_rGO) heterostructure composite, imparts long-term stability to the 2D heterostructure while providing additional electron pathways and significantly enhancing conductivity. Pt NPs synergistically increased the electrocatalytic activity of the electrochemical sensor's performance. Ternary nanocomposites were fabricated with different weight percentages (wt.%) of Pt NPs, ranging from 5 to 20. Characterizations of the samples (rGO, M, M_rGO, and 5–20 wt% Pt@M_rGO) were conducted through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy (RAMAN), and X-ray spectroscopy (XPS). Electrochemical evaluations of the samples were investigated in 0.1 M phosphate buffer solution (PBS) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) analyses. The analysis revealed that the ternary composite with 5 wt% of Pt NPs (5% Pt@M_rGO) exhibited a uniform well-distribution of Pt NPs and the highest oxidation peak for DA oxidation in CV studies. The presence of metal nanoparticles, aided by the synergistic effects between the MXene and rGO, resulted in an excellent DA sensor with a 0.147 μM detection limit from 1 to 14 μM linearity range. The sensor demonstrated outstanding selectivity, reproducibility (RSD values of 8.10%), repeatability (RSD value of 2.46%) and, excellent stability over 14 days. In human urine samples, the sensor exhibited excellent DA recovery (88.62–110.65%). This study significantly advances the development of electrochemical sensors for DA detection by introducing a rapid, facile and, efficient method for fabricating ternary composites. The fabricated sensor exhibited high sensitivity, excellent selectivity, and robust electrochemical performance, offering valuable insights into human and behavioral health advancements.

Graphene-Templated Achiral Hybrid Perovskite for Circularly Polarized Light Sensing.

This study points out the importance of the templating effect in hybrid organic-inorganic perovskite semiconductors grown on graphene. By combining two achiral materials, we report the formation of a chiral composite heterostructure with electronic band splitting. The effect is observed through circularly polarized light emission and detection in a graphene/α-CH(NH2)2PbI3 perovskite composite, at ambient temperature and without a magnetic field. We exploit the spin-charge conversion by introducing an unbalanced spin population through polarized light that gives rise to a spin photoconductive effect rationalized by Rashba-type coupling. The prepared composite heterostructure exhibits a circularly polarized photoluminescence anisotropy gCPL of ∼0.35 at ∼2.54 × 103 W cm-2 confocal power density of 532 nm excitation. A carefully engineered interface between the graphene and the perovskite thin film enhances the Rashba field and generates the built-in electric field responsible for photocurrent, yielding a photoresponsivity of ∼105 A W-1 under ∼0.08 μW cm-2 fluence of visible light photons. The maximum photocurrent anisotropy factor gph is ∼0.51 under ∼0.16 μW cm-2 irradiance. The work sheds light on the photophysical properties of graphene/perovskite composite heterostructures, finding them to be a promising candidate for developing miniaturized spin-photonic devices.

Ingeniously construction of industrial carbon fiber/nickel-iron layered double hydroxide heterostructure composite for high-efficient microwave absorption in aircraft

To enhance the survivability of military aircraft in electromagnetic warfare, carbon fiber/nickel-iron layered double hydroxide (CF/NiFe-LDH) composites with heterogeneous structure were constructed starting from the raw industrial carbon fiber (CF) by electrostatic self-assembly. By reasonably adjusting the mass ratio of CF and NiFe-LDH, the voids formed by LDH arrays stacked on the fiber surface are utilized to promote reflection and scattering of electromagnetic wave (EMW), optimizing impedance matching, as well as synergize dielectric-magnetic dual loss mechanism. Moreover, interfacial polarization effect induced by the abundant heterogeneous interfaces significantly enhance the ability of EMW dissipation. The optimized CF/NiFe-LDH heterostructure composite exhibits the minimum reflection loss (RLmin) value of −52.48 dB at mere 1.77 mm thickness and an expansive maximum effective bandwidth (EABmax) of 7.29 GHz at 2.14 mm. In addition, the computer simulation technology (CST) revealed that the radar scattering cross section (RCS) reduction of composites reaches up to 26.92 dBm2 at an incidence angle of 90°, demonstrating their excellent radar attenuation capability. Tremendously, the heterogeneous composites achieve an SRL1 value of 524.8, which is appreciably better than most of the EMW absorbing materials. The wondrous characteristics including lightweight, ultra-thin, high-efficient microwave absorbing ability of CF/NiFe-LDH heterostructure composites display potential application in fighter aircraft.

Ultrafast microwave synthesis of MoSSe@ graphene composites via dual anion design for long-cyclable Li-S batteries

Lithium-sulfur batteries (LSBs) have been increasingly recognized as a promising candidate for the next-generation energy-storage systems. This is primarily because LSBs demonstrate an unparalleled theoretical capacity and energy density far exceeding conventional lithium-ion batteries. However, the sluggish redox kinetics and formidable dissolution of polysulfides lead to poor sulfur utilization, serious polarization issues, and cyclic instability. Herein, sulfiphilic few-layer MoSSe nanoflake decorated on graphene (MoSSe@graphene), a two-dimensional and catalytically active hetero-structure composite, was prepared through a facile microwave method, which was used as a conceptually new sulfur host and served as an interfacial kinetic accelerator for LSBs. Specifically, this sulfiphilic MoSSe nanoflake not only strongly interacts with soluble polysulfides but also dynamically promotes polysulfide redox reactions. In addition, the 2D graphene nanosheets can provide an extra physical barrier to mitigate the diffusion of lithium polysulfides and enable much more uniform sulfur distribution, thus dramatically inhibiting polysulfides shuttling meanwhile accelerating sulfur conversion reactions. As a result, the cells with MoSSe@graphene nanohybrid achieved a superior rate performance (1091 mAh/g at 1C) and an ultralow decaying rate of 0.040 % per cycle after 1000 cycles at 1C.

Electrical Sensing of Molecular Spin State Switching in a Spin Crossover Complex Using an Organic Field‐Effect Transistor

AbstractAn organic semiconductor – spin crossover polymer composite heterostructure is fabricated, and it is integrated into an organic field‐effect transistor (OFET) with the aim to achieve electrical sensing of molecular spin state switching events. The OFETs display ≈50–70% increase in drain‐source current intensity when going from the low spin (LS) to the high spin (HS) state. This phenomenon is reversible without apparent fatigue and the application of a gate voltage significantly enhances the sensing sensitivity. Capacitance measurements and finite element calculations allow identifying mechanical stress, induced by the spin state switching, at the origin of the transistor response. These results open up appealing perspectives for the integration of spin crossover molecules into technological applications, such as soft robotics .

An electrochemical sensor based on porous heterojunction hollow NiCo-LDH/Ti3C2Tx MXenes composites for the detection of quercetin in natural plants.

Cubic hollow-structured NiCo-LDH was synthesized using a solvothermal method. Subsequently, clay-like Ti3C2Tx MXenes were electrostatically self-assembled with NiCo layered double hydroxides (NiCo-LDH) to form composites featuring three-dimensional porous heterostructures. The composites were characterized using SEM, TEM, XRD, XPS, and FT-IR spectroscopy. Ti3C2Tx MXenes exhibit excellent electrical conductivity and hydrophilicity, providing abundant binding sites for NiCo-LDH, thereby promoting an increase in ion diffusion channels. The formation of three-dimensional porous heterostructural composites enhances charge transport, significantly improving sensor sensitivity and response speed. Consequently, the sensor demonstrates excellent electrochemical detection capabilityfor quercetin (Qu), with a detection range of 0.1-20 µM and a detection limit of 23 nM. Additionally, it has been applied to the detection of Qu in natural plants such as onion, golden cypress, and chrysanthemum. The recovery ranged from 97.6 to 102.28%.

2D Se-Rich ZnSe/CoSe2@C Heterostructured Composite as Ultrastable Anodes for Alkaline-Ion Batteries.

2D transitional metal selenide heterostructures are promising electrode materials for potassium-ion batteries (PIBs) owing to the large surface area, high mechanical strength, and short diffusion pathways. However, the cycling performance remains a significant challenge, particularly concerning the electrochemical conversion reaction. Herein, 2D Se-rich ZnSe/CoSe2@C heterostructured composite is fabricated via a convenient hydrothermal approach followed by selenization process, and then applied as high-performance anodes for PIBs. For example, the capacity delivered by the heterostructured composite is mainly contributed to the synergistic effect of conversion and alloy/de-alloy processes aroused by K+, where K+ may highly insert or de-insert into Se-rich ZnSe/CoSe2@C. The obtained electrode delivers an outstanding reversible charge capacity of 214mA h g-1 at 1 A g-1 after 4000 cycles for PIBs, and achieves 262 mAh g-1 when coupled with a PTCDA cathode in the full cell. The electrochemical conversion mechanism of the optimized electrode during cycling is investigated through in situ XRD, Raman, and ex situ HRTEM. In addition, the heterostructured composite as anodes also displays excellent electrochemical performances for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs). This work opens up a new window for investigating novel electrode materials with excellent capacity and long durability.

Enhanced photoelectrochemical sensor for dopamine detection based on MOFs-derived ZnO and TpPa-1 heterostructure composite

This study used ZIF-8 metal–organic framework as a precursor to create a N-doped ZnO. Subsequently, covalent organic framework named TpPa-1 (Tp, 1,3,5-triformylphloroglucinol; Pa-1, p-phenylenediamine) with a ZnO heterostructure composite (ZnO/TpPa-1) was created through an in-situ synthesis approach. Due to its superior band structure and outstanding photocatalytic performance, the ZnO/TpPa-1 composite is a good candidate for the development of a new type of photoelectrochemical (PEC) sensor for the detection of dopamine (DA). According to experimental data, ZnO/TpPa-1/ITO had a photocurrent that was roughly 1.5 times higher than TpPa-1/ITO and 4.5 times higher than ZnO/ITO. The primary reason for this improvement was the synergistic effects brought about by effective light usage and charge transfer at the interface between the TpPa-1 π-conjugated backbone and ZnO porous structure. The determination ranges for DA demonstrated two linear ranges, 0.005–0.25 μmol/L and 0.25–1.00 μmol/L, and the detection limit was as low as 1.3 nmol/L. Moreover, the PEC sensor exhibited good stability, selectivity, repeatability, and suitability for real-world samples. This work provides important new understandings for covalent organic framework (COF)-based heterostructure design, which can be used to improve PEC sensor performance.

Novel 2D heterostructure composites of V2C MXene/TiO2 and graphene/TiO2 for platinum replacement in dye-sensitized solar cells

This study evaluates the potential of V2C MXene/TiO2 and Graphene/TiO2 composites as alternatives to platinum for counter-electrodes in dye-sensitized solar cells (DSSCs). V2C MXene was synthesized by selectively etching the aluminum layer from V2AlC MAX phase powder, resulting in multilayered V2C MXene. The layered morphologies of MXene and graphene were confirmed via Scanning Electron Microscopy (SEM), while their crystalline structures were validated using X-ray diffraction (XRD) analysis. SEM analysis confirmed the delaminated layered structure of graphene and the distinct layers of V2C MXene. XRD findings showed that MXene has significantly greater interlayer spacing than graphene, offering more catalytic sites for charge injection. Electrocatalysts were prepared by incorporating TiO2 paste with MXene and graphene, with TiO2 serving as a binder. These composites were then employed as counter-electrode materials in dye-sensitized solar cells. The MXene-based counter electrode achieved a photoconversion efficiency of 1.625 %, surpassing graphene-based (1.149 %) and Pt-based (1.567 %) counterparts under standard illumination. The efficiency of cells was meticulously characterized over an extended period. The results indicated that the efficiency of these cells remained stable over time. This stability suggests that MXene/TiO2 and Graphene/TiO2 based catalysts are robust and do not degrade with time.

Cyanide Linkage Isomerization Induced by Cobalt Oxidation-State Changes at a Co-Fe Prussian-Blue Analogue/ZnO Interface.

Understanding the interfacial composition in heterostructures is crucial for tailoring heterogenous electrochemical and photoelectrochemical processes. This work aims to elucidate the structure of a series of Co-Fe Prussian blue analogue modified ZnO (PBA/ZnO) electrodes with interface-sensitive vibrational sum frequency generation (VSFG) spectroscopy. Our measurements revealed, for the first time, a cyanide linkage isomerism at the PBA/ZnO interface, when the composite is fabricated at elevated temperatures. In situ VSFG spectro-electrochemistry measurements correlate the CoII➝CoIII oxidation with the flip of the bridging CN ligand from Co-NC-Fe coordination mode to a Co-CN-Fe one. Photoluminescence measurements and X-ray photoelectron spectroscopy reveal that this unprecedented linkage isomerism originates from surface defects, which act as oxidation sites for the PBA. The presence of such surface defects is correlated with the fabrication temperature for PBA/ZnO. Thus, this contribution identifies the interplay between the surface states of the ZnO substrates and the chemical composition of PBA at the ZnO surface, suggesting an easily accessible approach to control the chemical composition of the interface.

MoS2/SnS heterostructure composite for high-performance lithium-ion battery anodes

Layered metal sulfides are potential anode materials for lithium-ion batteries (LIBs) because their unique structure makes them suitable for Li+ de-intercalation. As a typical 2D layered material, MoS2 is a potential anode material for LIBs due to the weak van der Waals forces between the layers, which facilitates the de-intercalation of Li+ and supports multiple Li+. However, when MoS2 is used as anodes for LIBs material, rapid capacity decay hinders the application. Coupling two different materials to form a heterogeneous structure is an effective way to solve the above problems. In this work, one-pot hydrothermal method is proposed to construct MoS2/SnS heterostructure composites. The electrochemical properties are significantly enhanced, which could be attributed to the presence of heterogeneous structures, leading to increase the electrode charge transfer rate and interfacial reaction kinetics. The results show that the discharge capacity of the MoS2/SnS-1.5 electrode is about 1492.1 mAh/g at 500 mA/g. Furthermore, assembled MoS2@SnS-1.5||LiCoO2 full cell displays a high discharge capacity of 226.1 mAh/g after 50 cycles at 500 mA/g. This facile method provides the application value of layered metal sulfides as LIBs anode materials.

LiFe0.3Mn0.7PO4-on-MXene heterostructures as highly reversible cathode materials for Lithium-ion batteries

Two-dimensional (2D) heterostructure materials, incorporating the collective strengths and synergetic properties of individual building blocks, have attracted great interest as a novel paradigm in electrode materials science. The family of 2D transition metal carbides and nitrides (e.g., MXenes) has become an appealing platform for fabricating functional materials with strong application performance. Herein, a 2D LiFe0.3Mn0.7PO4 (LFMP)–on-MXene heterostructure composite is prepared through an electrostatic self-assembly procedure. The functional groups on the surface of MXenes possess highly electronegative properties that facilitate the incorporation of LFMPs into MXenes to construct heterostructure composites. The special heterostructure of nanosized-LiFe0.3Mn0.7PO4 and MXene provides rapid Li+ and electron transport in the cathodes. This LiFe0.3Mn0.7PO4-3.0 wt% MXene composite can exhibit an excellent rate capability of 98.3 mAh g−1 at 50C and a very stable cycling performance with a capacity retention of 94.3 % at 5C after 1000 cycles. Furthermore, NaFe0.3Mn0.7PO4-3.0 wt% MXene with stable cyclability can be obtained by an electrochemical conversion method with LiFe0.3Mn0.7PO4-3.0 wt% MXene. Ex-situ XRD suggests that LiFe0.3Mn0.7PO4-on-MXene achieves a highly reversible structural evolution with a solid solution phase transformation (LFMP→LixFe0.3Mn0.7PO4 (LxFMP), LxFMP→LFMP) and a two-phase reaction (LxFMP←→Fe0.3Mn0.7PO4 (FMP)). This work provides a new direction for the use of MXenes to fabricate 2D heterostructures for lithium-ion batteries.

In-situ interconnected 1D/2D/3D architectures of CNT/MoS2/Fe3O4 membranes for increasing degradation efficiency of penetrative electro-Fenton under low energy consumption

The electro-Fenton oxidation process for the degradation of organic pollutants in recalcitrant wastewater has garnered significant attention and research efforts in the field of advanced water treatment. This is primarily due to its highly effective degradation capabilities and the advantages it offers, including the avoidance of unsafe transportation and storage of hydrogen peroxide (H2O2). However, challenges such as relatively high energy consumption, complex operational requirements, and limited operational stability continue to pose significant economic constraints on the widespread application of electro-Fenton technology in water purification. In this study, we employed a secondary hydrothermal method to construct a multi-layered CNT/MoS2/Fe3O4 composite heterostructure in situ. Leveraging the synergistic effects of the introduced variable valence elements, Fe and Mo, and the interconnected multi-layered membrane structure, the CNT/MoS2/Fe3O4 electro-Fenton membrane holds promise in a permeable filtration system. Under the conditions of a current density of 1.50 mA/cm² and an electrolyte concentration of 0.50 mol/L, the CNT/MoS2/Fe3O4 composite membrane exhibited a degradation efficiency of over 90.00 % for 100.00 mg/L RhB within 10 minutes, and the degradation rate approached nearly 99.00 % at 60 minutes. Furthermore, the degradation efficiency for various recalcitrant organic dye wastewaters, including phenol, methyl orange, and methylene blue, could be maintained at levels ranging from 80.00 % to 97.00 %. Particularly, under optimized operating conditions, the specific energy consumption (EC) for the CNT/MoS2/Fe3O4 membrane process was measured at 0.60±0.01 kWh/m³, showcasing exceptionally low energy consumption characteristics. In conclusion, it is expected to contribute to the reduction of the overall consumption of heterogeneous electro-Fenton oxidation systems and enhance their operational efficiency. This innovative approach represents a significant advancement in the field, offering the potential to address the economic limitations associated with electro-Fenton technology in water quality purification.

Rational Fabrication of MoS2/g‐C3N4 Heterostructures for Efficient Photocatalytic Degradation of Rhodamine B

AbstractMolybdenum disulfide (MoS2) and graphitic carbon nitride (g‐C3N4) heterojunctions were prepared through the hydrothermal method and the calcination method (namely, MoS2/g‐C3N4‐1 and MoS2/g‐C3N4‐2) for the photocatalytic degradation of Rhodamine B. X‐ray diffraction and scanning electron microscopy confirmed the formation of a heterostructure composite between MoS2 and g‐C3N4. The bandgap of MoS2 and g‐C3N4 was studied with ultraviolet–visible diffuse reflection spectroscopy and electrochemical Mott‐Schottky tests. MoS2/g‐C3N4‐1 exhibits remarkable efficiency in degrading Rhodamine B, achieving 91.2 % degradation in 1 h, which is 1.06 times higher than MoS2/g‐C3N4‐2. Additionally, the MoS2/g‐C3N4‐1 heterojunction demonstrates good reusability, maintaining a degradation efficiency of 71.2 % after 5 cycles. The reason lies in that the MoS2/g‐C3N4‐1 possesses a larger specific surface area (33.078 m2g−1) than MoS2/g‐C3N4‐2 (28.621 m2g−1). Free radical quenching experiments indicate that ⋅O2− serves as the primary active species for photocatalytic degradation. The findings indicate that incorporating g‐C3N4 into MoS2 improves its photocatalytic capability due to aligned energy bands, promoting charge transfer, and reducing electron‐hole recombination.

Calcination process of porous metal–organic frameworks derived from nickel sulfide composites for supercapacitor and computer vision for investigating the porosity-electrochemical correlation

The utilization of metal–organic framework nanostructured electrode materials in supercapacitors and sensor applications is achieved by various chemical methods. In this study, we create NiS and NiS@MOF-BDC by employing nickel precursors and benzene dicarboxylic acid (BDC) as chelating organic linkers through a thermal reduction procedure at a temperature of 400 °C to produce the composite. The composite heterostructure enhanced the conductivity, porous characteristics, and diverse potential morphological qualities. The production of composite electrodes demonstrates a specific capacity of 260F/g (104C/g) when subjected to a current density of 1A/g. Additionally, these electrodes exhibit exceptional cyclic stability, enduring 5000 cycles, when used with a 2 M KOH electrolyte. Moreover, the synthesized composite HR-TEM images were analyzed using computer vision and AI techniques for estimating the porosity and investigating the enhanced electrochemical correlation.