Formulation of Hierarchical Nanowire-Structured CoNiO2 and MoS2/CoNiO2 Hybrid Composite Electrodes for Supercapacitor Applications.

Hierarchical porous nanowire-like MoS2/CoNiO2 nanohybrids were synthesized via the hydrothermal process. CoNiO2 nanowires were selected due to the edge site, high surface/volume ratio, and superior electrochemical characteristics as the porous backbone for decoration of layered MoS2 nanoflakes to construct innovative structure hierarchical three-dimensional (3D) porous NWs MoS2/CoNiO2 hybrids with excellent charge accumulation and efficient ion transport capabilities. Physicochemical analyses were conducted on the developed hybrid composite, revealing conclusive evidence that the CoNiO2 nanowires have been securely anchored onto the surface of the MoS2 nanoflake array. The electrochemical results strongly proved the benefit of the hierarchical 3D porous MoS2/CoNiO2 hybrid structure for the charge storage kinetics. The synergistic characteristics arising from the MoS2/CoNiO2 composite yielded a notably high specific capacitance of 1340 F/g at a current density of 0.5 A/g. Furthermore, the material exhibited sustained cycling stability, retaining 95.6% of its initial capacitance after 10 000 long cycles. The asymmetric device comprising porous MoS2/CoNiO2//activated carbon encompassed outstanding energy density (93.02 Wh/kg at 0.85 kW/kg) and cycling stability (94.1% capacitance retention after 10 000 cycles). Additionally, the successful illumination of light-emitting diodes underscores the significant potential of the synthesized MoS2/CoNiO2 (2D/1D) hybrid for practical high-energy storage applications.

Theoretical Justification of Structural, Magnetoelectronic and Optical Properties in QFeO3 (Q = Bi, P, Sb): A First-Principles Study.

One of the primary objectives of scientific research is to create state-of-the-art multiferroic (MF) materials that exhibit interconnected properties, such as piezoelectricity, magnetoelectricity, and magnetostriction, and remain functional under normal ambient temperature conditions. In this study, we employed first-principles calculations to investigate how changing pnictogen elements affect the structural, electronic, magnetic, and optical characteristics of QFeO3 (Q = Bi, P, SB). Electronic band structures reveal that BiFeO3 is a semiconductor compound; however, PFeO3 and SbFeO3 are metallic. The studied compounds are promising for spintronics, as they exhibit excellent magnetic properties. The calculated magnetic moments decreased as we replaced Bi with SB and P in BiFeO3. A red shift in the values of ε2(ω) was evident from the presented spectra as we substituted Bi with Sb and P in BiFeO3. QFeO3 (Q = Bi, P, SB) showed the maximum absorption of incident photons in the visible region. The results obtained from calculating the optical parameters suggest that these materials have a strong potential to be used in photovoltaic applications.

Density Functional Theory Approximations and Experimental Investigations on Co1-xMoxTe2 Alloy Electrocatalysts Tuning the Overall Water Splitting Reactions.

Understanding the relationship between electronic structure, surface characteristic, and reaction process of a catalyst helps to architect proficient electrodes for sustainable energy development. The highly active and stable catalysts made of earth-abundant materials provide a great endeavor toward green hydrogen production. Herein, we assembled the Co1-xMoxTe (x = 0-1) nanoarray structures into a bifunctional electrocatalyst to achieve high-performance hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics under alkaline conditions. The designed Co0.75Mo0.25Te and Co0.50Mo0.50 electrocatalysts require minimum overpotential and Tafel slope for high-efficacy HER and OER, respectively. Furthermore, we constructed a Co0.50Mo0.50Te2∥Co0.50Mo0.50Te2 device for overall water splitting with an overpotential of 1.39 V to achieve a current density of 10 mA cm-2, which is superior to noble electrocatalyst performance, with stable reaction throughout the 50 h continuous process. Density functional theory approximations and Gibbs free energy calculations validate the enhanced water splitting reaction catalyzed by the Co0.50Mo0.50Te2 nanoarrays. The partial replacement of Co atoms with Mo atoms in the Co0.50Mo0.50Te2 structure substantially enhances the water electrolysis kinetics through the synergistic effects between the combined metal atoms and the bonded chalcogen.

Tuning of electron transport layers using MXene/metal-oxide nanocomposites for perovskite solar cells and X-ray detectors.

This work elaborates on the decoration of metal oxides (ZnO and Fe3O4) between MXene sheets for use as the supporting geometry of PCBM electron transport layers (ETLs) in perovskite solar cells and X-ray detectors. The metal oxide supports for carrying the plentiful charge carriers and the hydrophobic nature of MXenes provide an easy charge transfer path through their flakes and a smooth surface for the ETL. The developed interface engineering based on the MXene/ZnO and MXene/Fe3O4 hybrid ETL results in improved power conversion efficiencies (PCEs) of 13.31% and 13.79%, respectively. The observed PCE is improved to 25.80% and 30.34% by blending the MXene/ZnO and MXene/Fe3O4 nanoparticles with the PCBM layer, respectively. Various factors, such as surface modification, swift interfacial interaction, roughness decrement, and charge transport improvement, are strongly influenced to improve the device performance. Moreover, X-ray detectors with the MXene/Fe3O4-modulated PCBM ETL achieve a CCD-DCD, sensitivity, mobility, and trap density of 15.46 µA cm-2, 4.63 mA per Gy per cm2, 5.21 × 10-4 cm2 V-1 s-1, and 1.47 × 1015 cm2 V-1 s-1, respectively. Metal oxide-decorated MXene sheets incorporating the PCBM ETL are a significant route for improving the photoactive species generation, long-term stability, and high mobility of perovskite-based devices.

Design of XS2 (X = W or Mo)-Decorated VS2 Hybrid Nano-Architectures with Abundant Active Edge Sites for High-Rate Asymmetric Supercapacitors and Hydrogen Evolution Reactions.

Two-dimensional layered transition metal dichalcogenides have emerged as promising materials for supercapacitors and hydrogen evolution reaction (HER) applications. Herein, the molybdenum sulfide (MoS2 )@vanadium sulfide (VS2 ) and tungsten sulfide (WS2 )@VS2  hybrid nano-architectures prepared via a facile one-step hydrothermal approach is reported. Hierarchical hybrids lead to rich exposed active edge sites, tuned porous nanopetals-decorated morphologies, and high intrinsic activity owing to the strong interfacial interaction between the two materials. Fabricated supercapacitors using MoS2 @VS2  and WS2 @VS2  electrodes exhibit high specific capacitances of 513 and 615 F g- 1 , respectively, at an applied current of 2.5 A g- 1  by the three-electrode configuration. The asymmetric device fabricated using WS2 @VS2  electrode exhibits a high specific capacitance of 222 F g- 1  at an applied current of 2.5 A g- 1  with the specific energy of 52 Wh kg- 1  at a specific power of 1 kW kg- 1 . For HER, the WS2 @VS2  catalyst shows noble characteristics with an overpotential of 56 mV to yield 10 mA cm- 2 , a Tafel slope of 39 mV dec-1 , and an exchange current density of 1.73 mA cm- 2 . In addition, density functional theory calculations are used to evaluate the durable heterostructure formation and adsorption of hydrogen atom on the various accessible sites of MoS2 @VS2  and WS2 @VS2  heterostructures.

A First-Principles Investigation on the Structural, Optoelectronic, and Thermoelectric Properties of Pyrochlore Oxides (La2Tm2O7 (Tm = Hf, Zr)) for Energy Applications.

A first-principles calculation based on DFT investigations on the structural, optoelectronic, and thermoelectric characteristics of the newly designed pyrochlore oxides La2Tm2O7 (Tm = Hf, Zr) is presented in this study. The main quest of the researchers working in the field of renewable energy is to manufacture suitable materials for commercial applications such as thermoelectric and optoelectronic devices. From the calculated structural properties, it is evident that La2Hf2O7 is more stable compared to La2Zr2O7. La2Hf2O7 and La2Zr2O7 are direct bandgap materials having energy bandgaps of 4.45 and 4.40 eV, respectively. No evidence regarding magnetic moment is obtained from the spectra of TDOS, as a similar overall profile for both spin channels can be noted. In the spectra of ε2(ω), it is evident that these materials absorb maximum photons in the UV region and are potential candidates for photovoltaic device applications. La2Tm2O7 (Tm = Hf, Zr) are also promising candidates for thermoelectric device applications, as these p-type materials possess ZT values of approximately 1, which is the primary criterion for efficient thermoelectric materials.

NaCl-Assisted Temperature-Dependent Controllable Growth of Large-Area MoS2 Crystals Using Confined-Space CVD.

Due to its semiconducting nature, controlled growth of large-area chemical vapor deposition (CVD)-grown two-dimensional (2D) molybdenum disulfide (MoS2) has a lot of potential applications in photodetectors, sensors, and optoelectronics. Yet the controllable, large-area, and cost-effective growth of highly crystalline MoS2 remains a challenge. Confined-space CVD is a very promising method for the growth of highly crystalline MoS2 in a controlled manner. Herein, we report the large-scale growth of MoS2 with different morphologies using NaCl as a seeding promoter for confined-space CVD. Changes in the morphologies of MoS2 are reported by variation in the amount of seeding promoter, precursor ratio, and the growth temperature. Furthermore, the properties of the grown MoS2 are analyzed using optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The electrical properties of the CVD-grown MoS2 show promising performance from fabricated field-effect transistors. This work provides new insight into the growth of large-area MoS2 and opens the way for its various optoelectronic and electronic applications.

Development of Binder-Free Three-Dimensional Honeycomb-like Porous Ternary Layered Double Hydroxide-Embedded MXene Sheets for Bi-Functional Overall Water Splitting Reactions.

In this study, a honeycomb-like porous-structured nickel-iron-cobalt layered double hydroxide/Ti3C2Tx (NiFeCo-LDH@MXene) composite was successfully fabricated on a three-dimensional nickel foam using a simple hydrothermal approach. Owing to their distinguishable characteristics, the fabricated honeycomb porous-structured NiFeCo-LDH@MXene composites exhibited outstanding bifunctional electrocatalytic activity for pair hydrogen and oxygen evolution reactions in alkaline medium. The developed NiFeCo-LDH@MXene electrocatalyst required low overpotentials of 130 and 34 mV to attain a current density of 10 mA cm-2 for OER and HER, respectively. Furthermore, an assembled NiFeCo-LDH@MXene‖NiFeCo-LDH@MXene device exhibited a cell voltage of 1.41 V for overall water splitting with a robust firmness for over 24 h to reach 10 mA cm-2 current density, signifying outstanding performance for water splitting reactions. These results demonstrated the promising potential of the designed 3D porous NiFeCo-LDH@MXene sheets as outstanding candidates to replace future green energy conversion devices.

Self-biased wavelength selective photodetection in an n-IGZO/p-GeSe heterostructure by polarity flipping.

Transparent semiconductor oxides with two-dimensional (2D) heterostructures have been extensively studied as new materials for thin-film transistors and photosensors due to their remarkable photovoltaic characteristics, making them useful for newly developed optoelectronics. Here we demonstrate the fabrication and characterization of an ITO/n-IGZO/p-GeSe transparent selective wavelength photodetector. The wavelength-dependent photovoltaic behavior of the n-IGZO/p-GeSe heterostructure under UV-Visible laser light shifts the I-V curves down with positive Voc and negative Isc values of about 0.12 V and -49 nA and 0.09 V and -17 nA, respectively. Interestingly, when an NIR laser irradiated the device, the I-V curves shifted up with negative Voc and positive Isc values of about -0.11 V and 45 nA, respectively. This behavior is attributed to the free carrier concentration induced by photogenerated carriers across the device at different points that varied with the wavelength-dependent photon absorption. Consequently, the direction of the electric field polarity across the junction can be flipped. This study demonstrates a zero-bias near-infrared (NIR) photodetector with a high photoresponsivity of 538.9 mA W-1, a fast rise time of 25.2 ms, and a decay time of 25.08 ms. Furthermore, we observed a detectivity (D) of 8.4 × 109 Jones, a normalized photocurrent to dark current ratio (NPDR) of 2.8 × 1010 W-1, and a noise equivalent power (NEP) of 2.2 × 10-14 W Hz-1/2. Our strategy opens alternative possibilities for scalable, low-cost, multifunctional transparent near-infrared photosensors with selective wavelength photodetection.

Fabrication of High-Performance Solar Cells and X-ray Detectors Using MoX2@CNT Nanocomposite-Tuned Perovskite Layers.

The interface design of inorganic and organic halide perovskite-based devices plays an important role to attain high performance. The modification of transport layers (ETL and HTL) or the perovskite layer is given the crucial inspiration to realize superior power conversion efficiencies (PCEs). The highly conducting 2D materials of CNT, graphene/GO, and transition-metal dichalcogenides (TMDs) are suitable substitutes to tune the electronic structure/work function of perovskite devices. Herein, the nanocomposites composed of molybdenum dichalcogenides (MoX2 = MoS2, MoSe2, and MoTe2) stretched CNT was embedded with HTL or perovskite layer to improve the resulted characteristics of perovskite devices of solar cells and X-ray detectors. A superior solar cell efficiency of 12.57% was realized for the MoTe2@CNT nanocomposites using a modified active layer-composed device. Additionally, X-ray detectors with MoTe2@CNT-modulated active layers achieved 13.32 µA/cm2, 3.99 mA/Gy·cm2, 4.81 × 10-4 cm2/V·s, and 2.13 × 1015 cm2/V·s of CCD-DCD, sensitivity, mobility, and trap density, respectively. Density functional theory approximation was used to realize the improved electronics properties, optical properties, and energy band structures in the MoX2@CNT-doped perovskites evidently. Thus, the current research paves the way for the improvement of highly efficient semiconductor devices based on perovskite-based structures with the use of 2D nanocomposites.

MoO3@MoS2 Core-Shell Structured Hybrid Anode Materials for Lithium-Ion Batteries.

We explore a phase engineering strategy to improve the electrochemical performance of transition metal sulfides (TMSs) in anode materials for lithium-ion batteries (LIBs). A one-pot hydrothermal approach has been employed to synthesize MoS2 nanostructures. MoS2 and MoO3 phases can be readily controlled by straightforward calcination in the (200-300) °C temperature range. An optimized temperature of 250 °C yields a phase-engineered MoO3@MoS2 hybrid, while 200 and 300 °C produce single MoS2 and MoO3 phases. When tested in LIBs anode, the optimized MoO3@MoS2 hybrid outperforms the pristine MoS2 and MoO3 counterparts. With above 99% Coulombic efficiency (CE), the hybrid anode retains its capacity of 564 mAh g-1 after 100 cycles, and maintains a capacity of 278 mAh g-1 at 700 mA g-1 current density. These favorable characteristics are attributed to the formation of MoO3 passivation surface layer on MoS2 and reactive interfaces between the two phases, which facilitate the Li-ion insertion/extraction, successively improving MoO3@MoS2 anode performance.

Bimetallic Cu/Fe MOF-Based Nanosheet Film via Binder-Free Drop-Casting Route: A Highly Efficient Urea-Electrolysis Catalyst.

Developing efficient electrocatalysts for urea oxidation reaction (UOR) can be a promising alternative strategy to substitute the sluggish oxygen evolution reaction (OER), thereby producing hydrogen at a lower cell-voltage. Herein, we synthesized a binder-free thin film of ultrathin sheets of bimetallic Cu-Fe-based metal-organic frameworks (Cu/Fe-MOFs) on a nickel foam via a drop-casting route. In addition to the scalable route, the drop-casted film-electrode demonstrates the lower UOR potentials of 1.59, 1.58, 1.54, 1.51, 1.43 and 1.37 V vs. RHE to achieve the current densities of 2500, 2000, 1000, 500, 100 and 10 mA cm-2, respectively. These UOR potentials are relatively lower than that acquired by the pristine Fe-MOF-based film-electrode synthesized via a similar route. For example, at 1.59 V vs. RHE, the Cu/Fe-MOF electrode exhibits a remarkably ultra-high anodic current density of 2500 mA cm-2, while the pristine Fe-MOF electrode exhibits only 949.10 mA cm-2. It is worth noting that the Cu/Fe-MOF electrode at this potential exhibits an OER current density of only 725 mA cm-2, which is far inconsequential as compared to the UOR current densities, implying the profound impact of the bimetallic cores of the MOFs on catalyzing UOR. In addition, the Cu/Fe-MOF electrode also exhibits a long-term electrochemical robustness during UOR.

A Facile Design of Solution-Phase Based VS2 Multifunctional Electrode for Green Energy Harvesting and Storage.

This work reports the fabrication of vanadium sulfide (VS2) microflower via one-step solvo-/hydro-thermal process. The impact of ethylene glycol on the VS2 morphology and crystal structure as well as the ensuing influences on electrocatalytic hydrogen evolution reaction (HER) and supercapacitor performance are explored and compared with those of the VS2 obtained from the standard pure-aqueous and pure-ethylene glycol solvents. The optimized VS2 obtained from the ethylene glycol and water mixed solvents exhibits a highly ordered unique assembly of petals resulting a highly open microflower structure. The electrode based on the optimized VS2 and exhibits a promising HER electrocatalysis in 0.5 M H2SO4 and 1 M KOH electrolytes, attaining a low overpotential of 161 and 197 mV, respectively, at 10 mA.cm-2 with a small Tafel slope 83 and 139 mVdec-1. In addition, the optimized VS2 based electrode exhibits an excellent electrochemical durability over 13 h. Furthermore, the superior VS2 electrode based symmetric supercapacitor delivers a specific capacitance of 139 Fg-1 at a discharging current density of 0.7 Ag-1 and exhibits an enhanced energy density of 15.63 Whkg-1 at a power density 0.304 kWkg-1. Notably, the device exhibits the capacity retention of 86.8% after 7000 charge/discharge cycles, demonstrating a high stability of the VS2 electrode.

Impact of Molybdenum Dichalcogenides on the Active and Hole-Transport Layers for Perovskite Solar Cells, X-Ray Detectors, and Photodetectors.

The interface architectures of inorganic-organic halide perovskite-based devices play key roles in achieving high performances with these devices. Indeed, the perovskite layer is essential for synergistic interactions with the other practical modules of these devices, such as the hole-/electron-transfer layers. In this work, a heterostructure geometry comprising transition-metal dichalcogenides (TMDs) of molybdenum dichalcogenides (MoX2  = MoS2 , MoSe2 , and MoTe2 ) and perovskite- or hole-transfer layers is prepared to achieve improved device characteristics of perovskite solar cells (PSCs), X-ray detectors, and photodetectors. A superior efficiency of 11.36% is realized for the active layer with MoTe2 in the PSC device. Moreover, X-ray detectors using modulated MoTe2 nanostructures in the active layers achieve 296 nA cm-2 , 3.12 mA (Gy cm2 )-1 and 3.32 × 10-4 cm2 V-1 s-1 of collected current density, sensitivity, and mobility, respectively. The fabricated photodetector produces a high photoresponsivity of 956 mA W-1 for a visible light source, with an excellent external quantum efficiency of 160% for the perovskite layer containing MoSe2 nanostructures. Density functional theory calculations are made for pure and MoX2 doped perovskites' geometrical, density of states and optical properties variations evidently. Thus, the present study paves the way for using perovskite-based devices modified by TMDs to develop highly efficient semiconductor devices.

Unveiling the Redox Electrochemistry of MOF-Derived fcc-NiCo@GC Polyhedron as an Advanced Electrode Material for Boosting Specific Energy of the Supercapattery.

Metal organic frameworks (MOFs), which constitute a new class of porous organic-inorganic hybrid materials, have gained considerable attention in the fields of electrochemical energy storage and conversion devices owing to their open topological structures, large surface areas, tunable morphologies, and extreme redox activity. A synthesis protocol that comprises coprecipitation followed by controlled calcination processes to design a battery-type electrode is used. This electrode consists of three-dimensional (3D), ant cave-like polyhedrons of nickel-cobalt alloy on graphitic carbon (GC; NiCo@GC) nanostructures; trimesic acid is used as a potential MOF-linker. The developed NiCo@GC sample exhibits mesoporous characteristics with the maximum surface area of 94.08 m2 g-1 at 77 K. In addition, the redox activity at different sweep rates reveals the battery-type charge storage behavior of the NiCo@GC electrode; its three-electrode assembly provides 444 C g-1 specific capacity at 2 A g-1 with long-term capacity retention. The constructed supercapattery (SC) devices (i.e., AC//NiCo@GC) achieved capacity, specific energy, and specific power are 74.3 mAh g-1 , 39.5 Wh kg-1 , and 665 W kg-1 , respectively. Owing to its reasonable electrochemical characteristics, the prepared NiCo@GC material is a promising candidate for supercapattery electrodes for portable electronic devices.

Deep-Ultraviolet (DUV)-Induced Doping in Single Channel Graphene for Pn-Junction.

The electronic properties of single-layer, CVD-grown graphene were modulated by deep ultraviolet (DUV) light irradiation in different radiation environments. The graphene field-effect transistors (GFETs), exposed to DUV in air and pure O2, exhibited p-type doping behavior, whereas those exposed in vacuum and pure N2 gas showed n-type doping. The degree of doping increased with DUV exposure time. However, n-type doping by DUV in vacuum reached saturation after 60 min of DUV irradiation. The p-type doping by DUV in air was observed to be quite stable over a long period in a laboratory environment and at higher temperatures, with little change in charge carrier mobility. The p-doping in pure O2 showed ~15% de-doping over 4 months. The n-type doping in pure N2 exhibited a high doping effect but was highly unstable over time in a laboratory environment, with very marked de-doping towards a pristine condition. A lateral pn-junction of graphene was successfully implemented by controlling the radiation environment of the DUV. First, graphene was doped to n-type by DUV in vacuum. Then the n-type graphene was converted to p-type by exposure again to DUV in air. The n-type region of the pn-junction was protected from DUV by a thick double-coated PMMA layer. The photocurrent response as a function of Vg was investigated to study possible applications in optoelectronics.

Hierarchical Mo2C@CNT Hybrid Structure Formation for the Improved Lithium-Ion Battery Storage Performance.

2-D transition metal carbides (TMCs)-based anode materials offer competitive performance in lithium-ion batteries (LIBs) owing to its excellent conductivity; cheaper, flexible uses; and superior mechanical stability. However, the electrochemical energy storage of TMCs is still the major obstacle due to their modest capacity and the trends of restacking/aggregation. In this report, the Mo2C nanosheets were attached on conductive CNT network to form a hierarchical 2D hybrid structure, which not only alleviated the aggregation of the Mo2C nanoparticle and facilitated the rapid transference of ion/electron, but also adapted effectually to the hefty volume expansion of Mo2C nanosheets and prevented restacking/collapse of Mo2C structure. Benefitting from the layered Mo2@CNT hybrid structure, the charge/discharge profile produced a 200 mAh g-1 discharge-specific capacity (second cycle) and 132 mAh g-1 reversible-discharge discharge-specific capacity (after 100 cycles) at 50 mA g-1 current density, with high-speed competency and superior cycle stability. The improved storage kinetics for Mo2@CNT hybrid structure are credited to the creation of numerous active catalytic facets and association reaction between the CNT and Mo2C, promoting the efficient electron transfer and enhancing the cycling stability.

Self-standing SnS nanosheet array: a bifunctional binder-free thin film catalyst for electrochemical hydrogen generation and wastewater treatment.

Hydrogen generation during wastewater treatment has remained a long-standing challenge for the environment preservation welfare. In the present work, we have fabricated a promising bifunctional thin film-based catalyst for hydrogen generation with concurrent wastewater treatment. The prepared catalyst film is a vertically oriented thin SnS (tin monosulfide) nanosheet array on a Ni-foam (SnS/NF) obtained via a solution process, demonstrating a promising electrocatalytic activity towards the generation of green H2 fuel at the cathodic side and the decomposition of urea waste at the anodic side. Notably, while assembling two identical electrodes as cathode and anode together with a reference electrode (i.e., SnS/NF∥SnS/NF vs. RHE assembly) in 1 M KOH aqueous electrolyte containing 0.33 M urea, the electrolyzer electrolyzed urea at a lower cell potential of 1.37 and 1.43 V (vs. RHE) to deliver a current density of 10 mA cm-2 and 50 mA cm-2, respectively, for the decomposition of urea at the anodic SnS/NF electrode and green hydrogen fuel generation at the cathodic SnS/NF electrode. This activity on electrocatalytic urea decomposition lies within the best performance to those of the previously reported sulfide-based and other catalytic materials. The promising catalytic activities of the SnS catalyst film are attributed to its combined effect of self-standing nanosheet array morphology and high crystallinity, which provides abundant active sites and a facile charge transfer path between the nanosheet arrays and the electrolyte. Thus, the present work offers a green avenue to the waste-urea treatment in water and sustainable hydrogen energy production.

Catalytic decontamination of organic/inorganic pollutants in water and green H2 generation using nanoporous SnS2 micro-flower structured film.

Recycling water and generation of H2 simultaneously as a green technology can be a key attraction in establishing environmental sustainability. Towards this endeavor, nanoporous SnS2 film electrodes deposited by a solution process on nickel foam demonstrate a promising electrocatalytic activity towards generation of H2 gas at cathode while the anodic reaction leads to the decomposition of urea-waste at the rate of 10 mA cm-2 in 1 M KOH with a lower cell-potential of 1.38 V vs RHE. The SnS2 electrode also demonstrates an excellent catalytic activity towards hydrogen evolution reaction in a wide pH range (0-14). In addition, the SnS2 film deposited on an FTO-substrate shows 97.56% photocatalytic-degradation of methylene-blue dye within 180 min under irradiation of visible light with a good recyclability of the photocatalyst, suggesting its high potentiality for the practical application. The demonstrated good electro- and photo-catalytic activities can be ascribed to the nanoporous structure of SnS2 film in a flower like 3D-fashion, offering availability of abundant active catalytic sites. Our results demonstrate the application of SnS2 nanoporous film as catalyst can be a significant greenery path for the removal of harmful inorganic/organic hazardous wastes from waste-water with simultaneous generation of green H2 fuel.

Process Steps for High Quality Si-Based Epitaxial Growth at Low Temperature via RPCVD.

The key process steps for growing high-quality Si-based epitaxial films via reduced pressure chemical vapor deposition (RPCVD) are investigated herein. The quality of the epitaxial films is largely affected by the following steps in the epitaxy process: ex-situ cleaning, in-situ bake, and loading conditions such as the temperature and gaseous environment. With respect to ex-situ cleaning, dry cleaning is found to be more effective than wet cleaning in 1:200 dilute hydrofluoric acid (DHF), while wet cleaning in 1:30 DHF is the least effective. However, the best results of all are obtained via a combination of wet and dry cleaning. With respect to in-situ hydrogen bake in the presence of H2 gas, the level of impurities is gradually decreased as the temperature increases from 700 °C to a maximum of 850 °C, at which no peaks of O and F are observed. Further, the addition of a hydrogen chloride (HCl) bake step after the H2 bake results in effective in-situ bake even at temperatures as low as 700 °C. In addition, the effects of temperature and environment (vacuum or gas) at the time of loading the wafers into the process chamber are compared. Better quality epitaxial films are obtained when the samples are loaded into the process chamber at low temperature in a gaseous environment. These results indicate that the epitaxial conditions must be carefully tuned and controlled in order to achieve high-quality epitaxial growth.