Effective Hydrothermal Method Research Articles

Voltammetric and electro-kinetic assessment of prucalopride at MnO2-rGO fabricated pencil graphite electrode

Development and design of rGO-based nanocomposite-modified carbon-based electrodes are necessary to enhance the selectivity and desired selectivity of the voltammetric sensors. In this work, a manganese dioxide-reduced graphene oxide (MnO2-rGO) fabricated pencil graphite electrode is described for the detection of prucalopride (PRU), which is used to treat chronic idiopathic constipation. A simple cost effective hydrothermal method was used to synthesize the needle-shaped MnO2. The MnO2-rGO nanocomposite was characterized using XRD, SEM, and FTIR spectroscopy to examine its microstructure and morphology. The results revealed that MnO2 needles are distributed on the flakes of the rGO, thereby enhancing the electro-catalytic activity of MnO2-rGO/PGE. The electrochemical performance of the developed MnO2-rGO/PGE was examined using CV, chronocoulometry, SWSV, and DPSV methods. The diffusion-controlled oxidation of the PRU at the MnO2-rGO/PGE produces an irreversible peak in all the voltammograms which were used to calculate several electro-kinetic parameters like electron transfer coefficient (α = 0.598), diffusion coefficient (Do = 1.62 × 10−5 cm2s−1), surface coverage (Γo = 1.55 × 10−9 molcm−2), and effective surface area. Furthermore, advanced SWSV and DPSV methods are proposed for the accurate, selective, and sensitive detection of the PRU in pharmaceutical samples. The reported values of detection limit (LOD) for the proposed SWSV and DPSV methods are 20.39 μM and 14.53 μM, respectively, which make them eco-friendly and affordable alternative tools for the quantification of the PRU in pharmaceutical samples.

Flexible Ni-Foam-Based Electrode with Novel MoS2/NiO Nanocomposite for Superior Supercapacitor Applications

Abstract In the present work a simple and effective hydrothermal method has been used to synthesize a nanocomposite of nickel oxide and molybdenum disulphide. Structural and optical characterizations of the as-synthesised MoS2/NiO nanocomposite nanoparticles were carried out using X-ray diffraction (XRD) and UV-visible spectroscopy techniques. The major peaks of MoS2 and NiO were detected in XRD, confirming the formation of composite. The reduced band gap 2.84 eV of MoS2/NiO nanocomposite as compared to pure NiO with 3.1 eV bandgap indicates a blue shift. Surface morphology of MoS2/NiO nanocomposite was measured using field-emission scanning electron microscopy, showing sheet-like structure with fine particle over laid on them. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to determine the processes of charge transfer in between electrodes, diffusion of molecules and ions within the electrolyte solution , and ion adsorption on an surface of electrode. The as-prepared composite shows enhanced specific capacitance of 246 F/g at scan rate of 20 mV/sec which was more than both base materials in pristine form. EIS results thus obtained may give a new direction for supercapacitor applications with the as-synthesized sample.

Synthesis of surfactant assisted Cu2ZnSnS4 (CZTS) photocatalysts for removal of dyes from wastewater

Herein, pure and hexamethylenetetramine (HMT) assisted Cu2ZnSnS4 were synthesized via effective hydrothermal method. The pure and HMT assisted Cu2ZnSnS4 samples were characterized to identify physicochemical behavior of photocatalysts. Prepared pure, 0.2 M, 0.4 M HMT assisted Cu2ZnSnS4 photocatalysts showed narrow band gap of 1.88, 1.47 and 1.23 eV. The HMT addition helped to reduce the photocatalyst’s band gap. The pure Cu2ZnSnS4 sample showed nanoparticles with higher agglomeration and improper growth. The 0.2 M HMT–Cu2ZnSnS4 samples showed smaller sized nanoparticles with little agglomeration on the surface of the nanoparticles. 0.4 M HMT-Cu2ZnSnS4 sample exhibited nanosheets like structure. The nanosheets were arranged in the interplanar manner. The obtained material was investigated to eliminate the RhB dye under visible light. The 0.4 M HMT-Cu2ZnSnS4 samples achieved higher efficiency of 84 %. The rate constant values of pure, 0.2 M, 0.4 M HMT-Cu2ZnSnS4 was 0.006, 0.009, 0.012 and 0.014 min−1. The active species corresponding to Cu2ZnSnS4 was holes which were confirmed by scavenger test. The good efficiency and rate constant values was attained by narrow band gap, electron hole transfer and better morphology which were attributed to the inclusion of HMT surfactant. 0.4 M HMT-Cu2ZnSnS4 will be prospective material for futuristic environmental remediation.

Thermoelectric Methylene Blue Degradation by SnSe-Doped Low-Content Copper

In important applications, thermoelectric technology has been widely applied for precise temperature control in intelligent electronics. This work synthesized and characterized low-content copper-doped SnSe thermoelectric catalysts using an easy and effective hydrothermal method. It was discovered that doping increased the crystal plane spacing of SnSe, increased the carrier concentration, and improved the thermoelectric properties. The best degradation was attained at x = 0.0025. The thermoelectric degradation performance of low-dose copper-doped tin selenide Sn1−xCuxSe (x = 0, 0.0005, 0.001, 0.0015, 0.002, 0.0025, 0.003), for the degradation of methylene blue from organic wastewater at 75 °C, was examined. Our research indicates that by using this approach, we can create more high-performance catalysts.

CQDs-interspersed floral CdS/NiAl-LDH heterojunction towards efficient photoreduction of CO2-to-CO

A series of hierarchical flower-like CdS/carbon quantum dots/NiAl-LDH (CCL) photocatalyst have been successfully prepared to achieve efficient conversion of CO2-to-CO via a simple yet effective hydrothermal method. In the CCL, interspersed-CQDs not only increase the number of reactive sites but also reduce inner electronic impedance with the assistance of light reflecting-scattering effect. This significantly improves electron migration efficiency and inhibits the recombination of photoinduced electron-holes pairs. Without any sacrificial agent or photosensitizer, the sample of CCL-1 exhibits the highest CO evolution rate of 7.04 μmol·g−1·h−1 in water under simulated sunlight illumination with a large specific surface area (129.15 m2 g−1) and an appropriate CQDs content of 15.2 wt%, which is 12.8- and 11.2-fold higher than those of pristine LDH, pure CdS, and many previously reported LDH-based counterparts. A type-Ⅱ interfacial charge transfer mechanism is proposed, where electrons migrate rapidly from CdS to LDH with highly-interspersed CQDs as unhindered electron conduction bridges. The present work outlines a simple and controllable LDH-based heterojunction, which give rise to superior photocatalytic activity for CO2 photoreduction.

Coupling Z-Scheme g-C3N4/rGO/MoS2 Ternary Heterojunction as an Efficient Visible Light Photocatalyst for Hydrogen Evolution and RhB Degradation.

Coupling heterostructures to synergistically improve the light adsorption and promote the charge carrier separation has been regarded as an operative approach to advance the photocatalytic performances. However, it is still challenging to construct heterostructures with appropriate optical properties and interfacial energy structures at the same time. In this work, a Z-scheme g-C3N4/rGO/MoS2 ternary composite photocatalyst is successfully synthesized via an effective hydrothermal method. The as-synthesized g-C3N4/rGO/MoS2 composite photocatalyst exhibited significant improvement for visible light absorption and boosted the separation efficiency of photoinduced electron-hole pairs. The g-C3N4/rGO/MoS2 system exhibited optimum visible-light-induced photocatalytic activity in hydrogen (H2) from water splitting and degrading pollutant rhodamin B (RhB), which is 22 times and 5 times higher than that of pure g-C3N4, respectively. The excellent photocatalytic activities are attributed to the synergetic effects of coupling rGO, g-C3N4, and MoS2 ternary structures to the composite photocatalyst. These combinations of intimate two-dimensional nanoconjugations can effectively inhibit charge recombination and accelerate charge transfer kinetics, forming a Z-scheme-assisted photocatalytic mechanism, thereby exhibiting superior photocatalytic activity.

Cobalt-doped MoS2 coated polyaniline composites as superior anode materials for high-performance lithium-ion batteries

Transition metal dichalcogenides represented by molybdenum disulfide (MoS2) have attracted worldwide attention due to their high specific capacity originating from the four-electron transfer reaction for lithium-ion batteries. Here, one nanoflower-like MoS2 with high specific surface area and more active sites is synthesized by a facile and effective hydrothermal method with cetyltrimethylammonium bromide (CTAB) as the surfactant. To improve the conductivity and structural stability of MoS2, Co doping and polyaniline (PANI) surface modification are carried out in sequence, and the obtained MoS2@Co/PANI hybrid materials show the improved electrochemical performance. In particular, the optimal hybrid material with 15 wt% PANI can exhibit a high discharge specific capacity of 1429.7 mAh·g−1 at 200 mA·g−1, and deliver a reversible capacity of 649.4 mAh·g−1 after 100 cycles. The excellent cycling and rate performances of MoS2@Co/PANI hybrid materials can be attributed to the enhanced conductivity resulting from the synthetic role of Co doping and PANI surface modification. One rational design is also offered to improve the electrochemical performance of functionalized electrode materials in lithium-ion batteries.

Green synthesized carbon dots as antibiotics sensor and fluorescent ink

Nearly all antibiotics cause significant health issues and environmental risks due to their unrestricted intake and delayed consumption. So, their detection and removal are of great concern. In this work, a novel Coleus zeylanicus leaves-derived nitrogen doped carbon dot (NCDs) based sensor was developed for the detection of antibiotics. The NCDs were synthesized via cost effective hydrothermal method. The NCDs with amorphous nature have an average size of 2.59 nm and a surface charge of -30.89 mV and exhibited excellent stability towards various experimental conditions. The NCDs worked as a fluorescent probe for levofloxacin (LEV) detection and an electrochemical sensing probe for the detection of amoxicillin (AMX). The fluorescence of NCDs was enhanced by LEV, and the limit of detection is obtained as 0.06 µM. The NCDs detected AMX with a LOD of 0.03 nM. Additionally, the effectiveness of NCDs in sensing levofloxacin and amoxicillin was confirmed in spiked water samples. Also, the role of NCDs as fluorescent ink was explored. In light of the findings of this study, it could be possible to find new ways to address environmental issues using carbon dots from sustainable sources.

Green synthesized carbon aerogel for electric double layer capacitor

As new-generation biomass-derived carbon materials, carbon aerogels offer opportunities in supercapacitor applications. Owing to their excellent properties viz., a synergy of unique interconnected hierarchical porous structure, high specific surface area (SSA), and electrical conductivity they prove their candidature in electric double layer capacitors (EDLCs). In this article, we represent a green synthesis of carbon aerogel using sugarcane juice as a carbon source via cost effective hydrothermal method instead of the traditional supercritical drying method which is more toxic, time-consuming, and expensive. The structural and compositional studies confirm the formation of Sugar Aerogel (SA). Additionally, the surface analysis shows the interconnected porous scoop-like structure with a high SSA of 2028 m2/g and a low bulk density of 0.08 g/cc. Furthermore, the synthesized powder was screen printed on flexible stainless-steel mesh to conduct electrochemical study at various Na2SO4 electrolyte concentrations (0.3, 0.6, 1.0, 2.0, 3.0 M). In 1.0 M Na2SO4 electrolyte, the SA showed 70% retention rate after 5500 cycles at 30 mA/cm2 current density over 1.9V potential window and also provides high energy density and power density 61.72 Wh/kg and 1588.33 W/kg respectively. Also, the SA||SA device exhibits stability over 1000 cycles with a 30% increment in capacitance with energy and power density 86 Wh/kg and 7920 W/kg. This study signifies the great potential of sugarcane juice to get SA via a simple, cost-effective, and environmentally friendly hydrothermal route for the fabrication of SC electrodes in neutral electrolyte Na2SO4.

Investigation of Oxygen Evolution Performance of Highly Efficient Water Electrolysis Catalyst: NiFe LDH/BPene

The oxygen evolution reaction (OER) plays a crucial role in hydrogen production through water electrolysis. However, the high overpotential and sluggish kinetics of the OER pose significant challenges. Layered double hydroxides (LDHs) have been widely used as highly active electrocatalysts to tackle these issues. To further enhance the catalytic activity of LDHs and optimize their composition and morphology, the rational design of highly efficient electrocatalysts is desirable. Considering the flexibility of heterogeneous structures in terms of their electronic structure and surface chemistry, this study employs a simple and effective hydrothermal synthesis method. By leveraging van der Waals (vdW) interactions, a heterostructure is constructed between nickel-iron bimetallic hydroxide (NiFe LDH) nanosheets and black phosphorene (BPene). The OER electrochemical test results demonstrate the superior electrocatalytic properties of the NiFe LDH/BPene heterostructure. The heterostructure exhibits remarkably low overpotential (180 mV) and Tafel slope (72.36 mV dec−1) at a current density of 10 mA cm−2. Furthermore, the stability test conducted for 30,000 s showed a current retention rate exceeding 93.00%. This work provides new perspectives into the electronic structure regulation of 2D heterostructures and highlights new avenues for tuning the electrocatalytic adsorption of emerging phosphorus-based materials.

Modulation for RuO2/TiO2 via Simple Synthesis to Enhance the Acidic Oxygen Evolution Reaction

Green hydrogen production with water splitting devices, especially a proton exchange membrane water electrolyzer (PEMWE), has received extensive attention. However, the sluggish kinetics of the oxygen evolution reaction (OER) still hinders its large-scale commercial application. Designing high-performance and low-cost electrocatalysts to drive the OER reaction remains a tough challenge. The active nanoparticles incorporating with metal oxide support is considered a promising strategy to improve durability and activity in acidic electrolytes. However, efficient synthesis methods without support premodification are rarely investigated. Herein, a simple but effective hydrothermal method accompanying the gradient annealing temperature was used to synthesize commercial TiO2 supported RuO2. The representative RuO2/TiO2-T250 required a low overpotential of 239 mV (@10 mA cm–2) with a Tafel slope value of 41.49 mV dec–1 and stability of over 20 h, far exceeding the performance of commercial RuO2. T250 exhibited a crystalline but hydrated microstructure, and the existing support-metal oxide interaction redistributed the electrons around Ru and Ti, which both gave rise to the activity of the electrocatalyst as well as hindered the Ru dissolution, thereby enhancing the OER performance. The synthesis strategy creates an important platform for designing more robust electrocatalysts for PEMWE application.

Methylthio-functionalized UiO-66 to promote the electron-hole separation of ZnIn2S4 for boosting hydrogen evolution under visible light illumination.

Solar-driven water splitting offers a leading-edge approach to storing abundant and intermittent solar energy and producing hydrogen as a clean and sustainable energy carrier. More importantly, constructing well-designed photocatalysts is a promising approach to develop clean hydrogen energy. In this paper, flower spherical UiO-66-(SCH3)2/ZnIn2S4 (UiOSC/ZIS) photocatalysts are successfully synthesized by a simple two-step hydrothermal method, and they exhibit high hydrogen production activity in light-driven water splitting. The optimized 30-UiOSC/ZIS (the content of UiOSC was 30 mg) composite exhibits optimal hydrogen production activity with a hydrogen production of 3433 μmol g-1 h-1, which is 5 and 235 times higher than that of pure ZIS and UiOSC, respectively. In addition, a long-cycling stability test has shown that the UiOSC/ZIS composite has good stability and recyclability. Experimental and characterization results show the formation of a type-II heterojunction between UiOSC and ZIS. This effectively suppresses the recombination of electrons-holes and promotes the carrier transfer, thus significantly improving the hydrogen production performance. This research further promotes the application of UiO-66-(SCH3)2 in the field of photocatalytic hydrogen production and provides a reference for the rational design of UiO-66-based composite photocatalysts.

Ni3S2 entrenched MWCNT composite as a low-cost Pt-free counter electrode for dye-sensitized solar cell: Conversion efficiency reached to 9.28%

• A simple and cost effective hydrothermal method was adopted to synthesize ultrafine Ni 3 S 2 /MWCNT hybrid CEs. • Ni 3 S 2 /CNT50 composite counter electrode has the maximum Power Conversion Efficiency (PCE) of 10.2 %. • This could be due to the Enhancing the light absorption property in the visible light region and diminish the recombination process. Engineering the surface structure and constructing a suitable internal conductive network is essential for the electron transfer rate and the active materials utilization efficiency of an electrode A novel porous micro-nanostructure based on nickel disulfide (Ni 3 S 2 ) nanoparticles interconnected with carbon nanotubes (CNTs) has been synthesized through a facile hydrothermal method. Shape, quantum states, optical behavior and phase purity have been elucidated using SEM, TEM, XPS, UV-DRD, PL and XRD spectra, respectively. Among all, Ni 3 S 2 /CNT50 composite counter electrode delivers the highest Power Conversion Efficiency (PCE) of 9.28 ± 0.03% with a short circuit current (J SC ) of 18.46 ± 0.01 mAcm −2 and open-circuit voltage (V OC ) of 0.73 ± 0.01 V. The improvement observed is due to the lower peak-to-peak separation (E pp ), higher exchange current density (J 0 ) and lower charge transfer resistance (R CT ). External quantum efficiency and electrochemical impedance analysis for the boost in efficiency and improved electrocatalytic activity with low charge-transfer resistance at (CE)/electrolyte interface are well in support for the synergistic effect of Ni 3 S 2 and MWCNTs.

Hydrothermal method-assisted synthesis of self-crosslinked all-lignin-based hydrogels

Lignin, as the most abundant aromatic biopolymer, is being widely studied to replace phenol and some other petroleum-based materials in the polymer industry. However, the low substitution of lignin and high levels of additives greatly limited the applications of lignin-based materials. Herein, we first propose a simple but effective hydrothermal method assisted synthesis for the fabrication of self-crosslinked lignin-based hydrogels (Lig-Scgel) with super-high-contents (75 wt%) of lignin and controllable mechanical properties. The self-crosslink mechanism was inspired by the repolymerization of lignins under a hydrothermal environment. The employment of self-condensation of lignin subunits in the synthesis of Lig-Scgel can significantly improve the degree of crosslinking, thereby greatly reducing the addition of toxic crosslinkers. The appearances, microstructures, crosslink densities, and mechanical properties of Lig-Scgels can be well controlled by simply altering the hydrothermal temperatures. This strategy not only promotes green and large-scale applications of lignin but also provides insights in the development of environment-friendly polymeric materials.

Two‐Dimensional MoxW1−xS2 Alloys for Nanogenerators Producing Record Piezo‐Output and Coupled Photodetectors for Self‐Powered UV Sensor

AbstractIn this work a novel sustainable, self‐driven UV photodetection system using ternary transition metal dichalcogenide (TMDC) alloy (MoxW1−xS2) is proposed by coupling a photodetector as a light intensity sensor and a piezoelectric nanogenerator (PENG) as a power source. Crystalline MoxW1−xS2 ternary alloy nanosheets are synthesized via cost effective hydrothermal method to fabricate a UV (365 nm) photodetector with extraordinary high responsivity (≈229 A W‐1). The microstructural, optical properties of different ternary alloy composition, along with their binary counterparts, have been studied. The optimized Mo0.5W0.5S2 ternary alloy nanosheets are used as fillers in PVDF matrix to fabricate flexible self‐polled PENGs, exhibiting piezoelectric open‐circuit output ≈50 V under finger tapping and a record high piezo‐voltage ≈187 V under impact of 12 kPa. By coupling the two devices, the output voltage of the PENG is tuned by the resistance of the photodetector, exhibiting superior voltage sensitivity (≈0.75 V µW‐1 cm‐2) with UV illumination. The impedance matching between the PENG and photodetector has been utilized to demonstrate self‐powered UV sensors by monitoring the on/off states of light‐emitting diode directly. This self‐powered, portable ternary TMDC alloy device is attractive for future real‐time monitoring of UV radiation and smart health sensors for IOT applications.

Development of Vanadium Oxide Nanopowder by Effective Hydrothermal Method: A New Insight Analysis on Optical, Third Order Non-Linear Optical, Structural, Electrical, Morphological and Spectral Significance

Development of Vanadium Oxide Nanopowder by Effective Hydrothermal Method: A New Insight Analysis on Optical, Third Order Non-Linear Optical, Structural, Electrical, Morphological and Spectral Significance

MoS2‐Functionalized Graphene Composites—Potential Replacement for Lubricant Friction Modifier and Anti‐Wear Additives

AGOC(n)/MoS2 composites are synthesized by a facile and effective hydrothermal method. Different mass ratios of AGOC(n) to MoS2 are prepared for producing AGOC(n)/MoS2 composites and their tribological properties at different weight percentages in Group III petroleum‐based oil are investigated. The as‐prepared composites are characterized using Fourier transform infrared (FTIR), field emission scanning electron microscope/energy dispersive X‐ray (FESEM/EDX), Raman, X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). The performance of the AGOC(n)/MoS2 composites as lubricant additives is investigated on four‐ball testers. The results indicate that AGOC(n)/MoS2 could improve the friction‐reduction and antiwear properties of the petroleum‐based oil. In particular, the AGOC14/MoS2 composite with a 1:1 mass ratio shows the highest reduction of friction coefficient and wear scar diameter by 53% and 63%, respectively. The excellent tribological behavior of the composites is attributed to the synergetic effect and unique layered structure of AGOC(n) and MoS2.

Synthesis dielectric and mechanical properties of paddy straw derived graphene quantum dots-stone waste nanocomposite

In present work, graphene quantum dots (GQDs) was synthesized from paddy straw using the cost effective hydrothermal method. High strength and moisture resistant GQDs reinforced stone waste particulates nanocomposites were prepared for the first time. Structural, morphological and functional group were analyzed using X-Ray diffraction, SEM and FT-IR techniques, respectively. Interestingly, GQDs-stone nanocomposites exhibited low dielectric constant (ɛ′ ~ 10) as compared to pristine stone composites (ɛ′ ~ 55). High flexural strength up to 60 MPa was achieved from GQDs reinforcement in stone waste nanocomposites. The high flexural strength and low dielectric constant from GQDs-stone waste polymer composite sheet were attributed due to high mechanical strength and sp2 hybridized covalent bond of GQDs and its high conductivity.

Three-dimensional hierarchical oxygen vacancy-rich WO3-decorated Ni foam evaporator for high-efficiency solar-driven interfacial steam generation

Solar steam generation is considered to be an effective strategy to alleviate the global water shortage problem. Therefore, exploring highly efficient and thermal stability photothermal conversion materials is highly essential and urgent. In this work, we develop a three-dimensional (3D) oxygen vacancy-rich WO3 with ‘‘nanorod array grown on nanosheet array” unique architecture decorated on Ni foam (denoted as WO3−x/NF) through a simple and effective hydrothermal method followed by an annealing route, which is applied as light-absorbing material. The 3D hierarchical porous unique structure of the WO3−x/NF evaporator can supply a channel steam escaping and enhance the light trapping due to the multi-scattering effect, and the localized surface plasmon resonance (LSPR) effects of WO3−x also contribute to increase the light absorption in the full solar spectrum. The as-prepared WO3−x/NF evaporator reveals a high solar absorption (95%), an evaporation rate of 1.50 kg m−2 h−1 under one sun illumination, and a light-to-heat conversion efficiency of about 88%, as well as stable salt-resistance performance. The water purification results show that WO3−x/NF evaporator has a significant effect on seawater desalination without significant salt accumulation and purification of heavy metal wastewater. Furthermore, the first-principles calculations reveal that WO3 with oxygen vacancies has a narrower bandgap, which is more conducive to absorb solar energy from the whole spectrum. This work can provide a new avenue toward the design of other high photothermal conversion system.

MnCo2S4 – MXene: A novel hybrid electrode material for high performance long-life asymmetric supercapattery

The supercapattery, an ideal electrochemical energy storage device, which can deliver high energy like battery and high power like supercapacitor. Transition metal sulphides’ energy storage capabilities have unfurled beyond the realm of ruthenium and manganese-based oxides by the versatile affordable sulphospinel transition metal sulphides such as MnCo2S4 (MCS). The advancement of synergistic nano-architectures of these transition metal sulphides with two-dimensional MXene material adulated the conductivity and highly reversible redox nature. The hybrid MCS-MXene was synthesised through facile cost effective hydrothermal method and the material were characterised using basic X-Ray Diffraction (XRD) to advanced tools as like electron energy loss spectroscopy (EELS). The electrochemical results depict that the supercapattery electrode of 2D synergistic MCS-MXene hybrid architectures shows highly improved specific capacitance of 600 C/g at 1 A/g current density than pristine MXene and MCS. The fabricated asymmetric supercapattery using hybrid MCS-MXene and bio-derived activated carbon (AC) shows a high specific energy and power density of 25.6 Wh/kg and 6400 W/kg, respectively with excellent cycling stability of 100% capacitance retention after 12,000 cycles.