Facile Hydrothermal Route Research Articles

Tailoring of 2D MoS2 microspheres on 3D low-cost DE for the efficient removal of hazardous cationic dyes

The primary challenge involved in the water treatment field is to treat/clean the contaminated waste dye solutions before it releases into the environment. Industrial contaminant such as dyes are released into water streams, rendering the water unfit for further use. Treatment of such dye contaminants is still a challenging tasks that has evolved as one of the leading issues in environmental remediation. Some of the significant limitations in dye adsorption include time-consuming, synthetic routes, expensive adsorbents, more contact time, less adsorption performances and use of more adsorbents. To address such problems, herein in this work, 2D MoS2 molybdenum disulfide)-3D DE (diatomaceous earth) hybrid materials were synthesized by a facile and efficient hydrothermal route. The prepared innovative combination of 2D & 3D porous hybrid materials demonstrated to be efficient adsorbents for the efficient removal of malachite green (MG) dye from aqueous solution with superior 97 % removal efficiency within 5 mins and with an extended 60 mins of contact time possible to achieve 99.9 % of removal efficiency. Furthermore, the maximum adsorption capacity for DE was only 0.78 mg/g and developed 2D MoS2-3D DE exhibited an outstanding 110 mg/g for MB dye which is a significant improvement when compared to pristine DE. On the other hand, the 2D MoS2-3D DE was explored as a membrane-based filter for the removal of other important cationic pollutant methylene blue (MB) dye which showed 100 % rejection for varied MB volumes from 50 to 200 mL with average flux rate of 2200 L.m−2.h−1. Additionally, the 2D-3D hybrid adsorbents substantiated with better recyclability with up to 5 cycle performances which could be an excellent candidate for the removal of industrially important cationic dyes in the future.

2H-MoS2 as an electrode material for oxygen reduction reaction and supercapacitor applications

Molybdenum Disulfide (MoS2) is a two-dimensional material having hexagonal crystal structure, which is widely used as a catalyst in various electrochemical reactions. In the present work, 2H-MoS2 nano-structures are synthesized in the exfoliated form by a facile hydrothermal synthesis route and are studied as electrode material for electrochemical devices. Formation of 2H-MoS2 phase has been confirmed by XRD and is also supported by the presence of E12g and A1g bands in Raman spectroscopy which appears due to the formation of layered MoS2 sheets. The FESEM images show MoS2 sheets in the form of flower-like microstructures. The ORR limiting current density obtained from polarization curves is 3.51 mA/cm2 at 2400 rpm with an onset potential of 0.06 V vs RHE. The specific capacitance of 2H-MoS2 as determined from CV and GCD are 115.42 F/g (at a scan rate of 10 mV/s) and 57.69 F/g (at current density 0.5 A/g) respectively and the samples retain 71.5 % of specific capacitance after 5000 CV cycles. The sample exhibited an electrochemical double layer capacitive (EDLC) behavior with partial pseudo-capacitance. The results suggest that the MoS2-based materials are potential candidates as electrodes in the electrochemical devices.

Sb2X3 (X = S, Se) nanowires/graphene aerogel monoliths for effective photodegradation of dye/drug under visible light irradiation

The visible-light-responsive photocatalysts with high efficiency have been attracting tremendous focus in environmental remediation. Herein, three-dimensional (3D) Sb2X3 (X = S, Se) nanowires/graphene aerogel (Sb2X3/GA) monoliths were prepared by a facile hydrothermal route. The as-prepared Sb2X3/GA monoliths show the shape of a cylinder with a hierarchical porous structure. FESEM and porosimetry analyses revealed that the monoliths have high porosity, large total pore area as well as large pore volume. Sb2X3/GA demonstrated excellent photodegradation performance for the representative anionic/cationic dyes (methyl orange, rhodamine B, and crystal violet) and antibiotic drug (tetracycline hydrochloride) under 120 min of visible light irradiation. The degradation efficiencies of Sb2X3/GA were found to be 92.6–99.8% for the above-mentioned dye/drug, which were much larger than that of the pristine Sb2X3 nanowires. The enhanced photodegradation activity could be ascribed to the synergistic effect between the Sb2X3 nanowires and graphene aerogel, which was confirmed by the results of the photoluminescence and electrochemical impedance spectra. These findings provide an innovative strategy for designing 3D visible-light-responsive photocatalysts for water purification.

Quad-band microwave absorbers based on MoO3-x@MWCNT with tunable morphologies for multifunctional multiband absorption

Microwave absorption materials can effectively eliminate harmful electromagnetic radiation to protect humanity, but it still remains challenging to attain absorbers with quad-band compatible strong absorption to date. Herein, MoO3-x@MWCNT with tunable morphologies was fabricated via a facile one-step hydrothermal route and their microwave absorption properties in different frequency bands were systematically investigated, along with the multifunctional properties. The absorbers with a hollow hexagonal prism and cauliflower-like morphologies can be tailored by changing the hybrid ratios of MoO3-x rich in vacancy defects and defective MWCNT from 5:1 (S1), 6:1 (S2) to 7:1 (S3), contributing to quad-band absorption (S-, C-, X- and Ku-bands) with maximum effective absorption bandwidth of 3.68 GHz for S2 and tri-band absorption (S-, X- and Ku-bands) with maximum effective absorption bandwidth of 4.67 GHz for S3, and optimal reflection loss can reach −62.23 dB when a compound ratio of 30% is satisfied in S3/paraffin. The conspicuous quad-band absorption and reflection loss are manipulated by the synergetic effects of multiple factors including porous structures, numerous defects and heterogeneous interfaces, etc. Additionally, remarkable fire-retardancy, photothermal de-icing and antibacterial performance of synthesized MoO3-x@MWCNT-based absorbing coating are expected to deliver solutions for complex communication and detection in the military and civil fields.

Z-scheme promoted heterojunction photocatalyst (Ag@AgVO3 /rGO/CeVO4) with improved interfacial charge transfer for efficient removal of aqueous organics irradiated under LED light

A facile hydrothermal route was followed to obtain a ternary composite Ag@AgVO3/rGO/CeVO4 with in-situ deposition of Ag nanoparticles over the AgVO3 nano-belts. The in-situ deposition was promoted and enhanced with the introduction of GO. The as-synthesized composite demonstrated remarkable visible light harvesting efficiency greater than 75% in the visible region. The charge separation and light harvesting properties were achieved through the Z-scheme mechanism mediated through rGO and the electron trapping/Schottky barrier effect from Ag nanoparticles. The reduction in the width of space charge region (∼2.5 times) and simultaneous increase in the density of charge carriers (2.3∗1018) promoted the LED irradiated photocatalytic performance. The decay time of the charge carriers were prolonged in the order of 4.46 s implying the enhancement in the charge separation. The studies were extended to charge trapping and the band structure modelling. The later emphasized on the prominence of Z-scheme mechanism with hole mediated degradation pathway. The LED photocatalysis demonstrated a removal efficiency of 87.20% for MB and 55.51% for phenol with a average AQE of 29.28% (MB) and 13.90% (phenol) for the ternary. The mineralization efficiency determined through TOC analysis was found to be 71.72%, and 66.43% for MB and phenol system respectively.

SrTiO3–TiO2 Heterostructured Nanotube Arrays for Ultrafast Ethanol Sensing

Diverse metal oxide semiconductors have bloomed in chemical sensing applications providing opportunities and challenges. In this work, SrTiO3–TiO2 heterostructured nanotube arrays were well designed via the electrochemical synthesis of TiO2 nanotubes, followed by a facile one-step hydrothermal route by varying the amount of Sr(OH)2·8H2O precursor (0.25–25 mM) to grow different quantities of SrTiO3 on TiO2 nanotubes. The crystalline nature, morphology, and synthesis mechanism of the nanotube array were fully elucidated. Vertically aligned SrTiO3–TiO2 heterostructured nanotube arrays were then sandwiched between the Ti bottom electrode (substrate as well) and Au top electrode to fabricate the metal–insulator–metal type sensors. SrTiO3–TiO2 nanotube sensors exhibited ethanol-selective behavior where the highly defective SrTiO3 layer acted as the main sensitive material that interacted with target species like ethanol. The SrTiO3–TiO2 heterostructured nanotube array sensor synthesized with 0.25 mM Sr(OH)2 precursor exhibited an excellent response magnitude (Ra/Rg) of ∼556 with an ultrafast response time of 0.4 s toward 50 ppm ethanol at an operating temperature of 150 °C. Moreover, the sensor exhibits excellent stability, a low detection limit of 2.94 ppb, and good selectivity. All the SrTiO3–TiO2 heterostructured nanotube array sensors showed promising humidity-tolerant behavior, and negligible change in response was obtained in the presence of 80% humid ambient air. The mechanism behind the modulated VOC sensing characteristics was explained with the comprehensive effects of the larger specific surface area, high surface defects, and modulated oxygen vacancies coming from the SrTiO3 modification in the nanotube structures.

Trimetallic Co-Ni-Mn metal-organic framework as an efficient electrocatalyst for alkaline oxygen evolution reaction

• CoNi-, CoMn-, and CoNiMn-MOF were synthesized via a facile hydrothermal route. • CoNiMn-MOF exhibited the highest electrocatalytic activity toward OER. • A η 20 of 220 mV and a Tafel slope of 66 mV dec −1 were measured for CoNiMn-MOF. • CoNiMn-MOF displayed excellent electrochemical stability for 20 h. Designing efficient and inexpensive catalysts toward the oxygen evolution reaction (OER) is vital for achieving sustainable and green hydrogen fuel production through water electrolysis. Herein, we have synthesized several bi- and trimetallic metal–organic frameworks (MOFs) composed of Co, Ni, and Mn metals and benzene-1,3,5-tricarboxylic acid linker. The MOFs were prepared via a simple hydrothermal method, and their electrocatalytic performances in alkaline OER were investigated. A battery of analytical techniques was employed to characterize the as-synthesized materials, including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and nitrogen adsorption–desorption analysis. It was found that the trimetallic CoNiMn-MOF exhibits the highest electrocatalytic activity in OER, with an overpotential of 220 mV at the current density of 20 mA cm −2 , a Tafel slope of 66 mV dec −1 , and a very good electrochemical stability for 20 h. Remarkably, this trimetallic MOF can deliver a high current density of 250 mA cm −2 at an overpotential of only 293 mV. These findings indicate the great potential of CoNiMn-MOF as a high-performance and cost-effective catalyst for the electrochemical oxidation of water.

Microwave-assisted synthesis of porous heterojunction ZnO/ZnMn2O4 microrods for efficient degradation of organic pollutants

The ZnO/ZnMn 2 O 4 heterojunction photocatalysts are synthesized through microwave-assisted hydrothermal route, and show high photocatalytic activity towards methylene blue and methyl orange under UV light irradiation. • Microwave-assisted hydrothermal method is used to obtain porous heterojunction ZZMO. • The active species in the photocatalytic system are the O 2 − and h + by trapping experiments. • The enhanced catalytic activities of ZZMO result from the formation of n-p junction. • A maximum degradation of MB is estimated as ∼100% for optimized ZZMO within 60 min. • Photocatalytic degradation mechanism of hetero ZZMO towards organic dyes is proposed. Photocatalytic activity of a semiconductor with low band gap has been greatly suppressed due to the high recombination rate of photogenerated charge carriers. The most economic and efficient remedy is to construct a heterojunction to enhance the transfer/separation of interfacial charge carriers. Inspired by this, the rod-like ZnO/ZnMn 2 O 4 composite heterojunction photocatalysts are synthesized via a facile template-free microwave-assisted hydrothermal route. The photocatalytic activities of the as-prepared samples are evaluated by the photocatalytic degradation of methylene blue and methyl orange under UV light irradiation. The optimized ZnO/ZnMn 2 O 4 demonstrates enhanced photocatalytic efficiencies towards degradation of methylene blue and methyl orange, which are about 4.3 and 3.0 times higher than those of pure ZnO, respectively. Furthermore, the composite could still maintain good photocatalytic activity for photocatalytic methylene blue even after four recycles. The active species in the photocatalytic system are·O 2 − and h + , which can be confirmed by the trapping experiments. The enhanced photocatalytic activity of ZnO/ZnMn 2 O 4 composite may result from the formation of n-p junction, which supports the generation of·O 2 − and h + . More significantly, the intrinsic photocatalytic degradation mechanism of ZnO/ZnMn 2 O 4 composite towards organic dyes is tentatively proposed.

Efficient Oxygen Vacancy Defect Engineering for Enhancing Visible-Light Photocatalytic Performance over SnO2-x Ultrafine Nanocrystals.

Regardless of its good electron-transfer ability and chemical stability, pure Zn2SnO4 (ZSO) still has intrinsic deficiencies of a narrow spectral response region, poor absorption ability, and high photo-activated carrier recombination rate. Aiming to overcome the deficiencies above-mentioned, we designed a facile hydrothermal route for etching ZSO nanoparticles in a dilute acetic acid solution, through which efficient oxygen vacancy defect engineering was accomplished and SnO2−x nanocrystals were obtained with an ultrafine particle size. In comparison with the untreated ZSO nanoparticles, the specific surface area of SnO2−x nanocrystals was substantially enlarged, subsequently leading to the notable augmentation of active sites for the photo-degradation reaction. Aside from the above, it is worth noting that SnO2−x nanocrystals were endowed with a broad spectral response, enhancing light absorption capacity and the photo-activated carrier transfer rate with the aid of oxygen vacancy defect engineering. Accordingly, SnO2−x nanocrystals exhibited significantly enhanced photoactivity toward the degradation of the organic dye rhodamine B (RhB), which could be imputed to the synergistic effect of increasing active sites, intensified visible-light harvesting, and the separation rate of the photo-activated charge carrier caused by the oxygen vacancy defect engineering. In addition, these findings will inspire us to open up a novel pathway to design and prepare oxide compound photocatalysts modified by oxygen vacancy defects in pursuing excellent visible-light photoactivity.

High-performance nonenzymatic electrochemical glucose biosensor based on AgNP-decorated MoS2 microflowers

A facile hydrothermal route was used to synthesize silver nanoparticle (AgNP)-decorated microflower molybdenum disulfide (MoS2-MF) for bio-electrochemical platform fabrication to detect nonenzymatic glucose concentration. The morphologies of the materials were studied by scanning electron microscopy, and their structural characteristics were analyzed by X-ray diffractometry and energy-dispersive X-ray spectroscopy. The electrochemical characteristics of the AgNPs/MoS2-MF/PtE biosensor were studied by cyclic voltammetry. The obtained data indicated that the developed nonenzymatic glucose sensor has a large linear response between 1.0 and 15.0 mM, a limit of detection of as low as 1.0 mM, and a sensitivity of 46.5 μA nM−1 cm−2. The biosensor also displayed outstanding selectivity, stability, reproducibility, and repeatability. Additionally, the AgNPs/MoS2-MF/PtE biosensor was utilized to detect glucose concentration in real sample and showed practical application potential for glucose detection.

Enhanced pseudocapacitive properties of divalent (Mn, Fe, Zn) substituted NiCo2O4 nanorods

• Divalent (Mn, Fe, Zn) substituted NiCo 2 O 4 by facile hydrothermal route, • The Mn substituted NiCo 2 O 4 demonstrates high performance supercapacitor, • Specific capacitance: 1272F/g at 1 A/g current density, • Energy density: 35.77 Wh/kg, • Power density: 660.39 W/kg. We report the electrochemical performance of divalent (Mn, Fe, Zn) substituted NiCo 2 O 4 nanorods, developed using facile hydrothermal route. The physico-chemical properties of the electrode materials were analysed using XRD, FESEM, TEM, HRTEM, FFT, EDAX and XPS. The performance of Mn substituted NiCo 2 O 4 was found to be the best divalent replacement, with a specific capacitance of 1272 F/g at 1 A/g current density, an energy density of 35.77 Wh/kg, and a power density of 660.39 W/kg. The capacitance of Fe and Zn substituted NiCo 2 O 4 was found to be lower than that of the pure NiCo 2 O 4 electrode material, which may be owing to the lower catalytic activity of Fe and Zn. The Mn substituted NiCo 2 O 4 demonstrates that it has the potential to be used as a high performance supercapacitor in practical applications.

Scheelite-type rare earth vanadates TVO4 (T = Ho, Y, Dy) electrocatalysts: Investigation and comparison of T site variations towards bifunctional electrochemical sensing application

In the wake of the recent COVID-19 pandemic, antibiotics are now being used in unprecedented quantities across the globe, raising major concerns regarding pharmaceutical pollution and antimicrobial resistance (AMR). In view of the incoming tide of alarming apprehensions regarding their aftermath, it is critical to investigatecontrol strategies that can halt their spread. Rare earth vanadates notable for their fundamental and technological significance are increasingly being used as electrochemical probes for the precise quantification of various pharmaceutical compounds. However, a comprehensive study of the role of the cationic site in tailoring the response mechanism is relatively unexplored. Hence, in this work we present a facile hydrothermal synthesis route of rare earth vanadates TVO4 (T = Ho, Y, Dy) as efficient electrocatalyst for the simultaneous detection of nitrofurazone (NF) and roxarsone (RX). There appears to be a significant correlation between T site substitution, morphological and the electrochemical properties of rare earth metal based vanadates. Following a comparative study of the electrochemical activity, the three rare-earth vanadates were found to respond differently depending on their composition of T sites. The results demonstrate that Dy-based vanadate displays increased electrical conductivity and rapid charge transfer characteristics. Thus, under optimal reaction conditions DyVO4- based electrodes imparts outstanding selectivity towards the detection of NF and RX with an extensive detection window of NF = 0.01–264 µM & RX = 0.01–21 µM and 36–264 µM and low detection limit (0.002, 0.0009 µM for NF and RX, respectively). In real-time samples, the proposed sensor reveals itself to be a reliable electrode material capable of detecting residues such as NF and RX.

Construction of Co,N-Coordinated Carbon Dots for Efficient Oxygen Reduction Reaction.

For the sake of the oxygen reduction reaction (ORR) catalytic performance, carbon dots (CDs) doped with metal atoms have accelerated their local electron flow for the past few years. However, the influence of CDs doped with metal atoms on binding sites and formation mechanisms is still uncertain. Herein, Co,N-doped CDs were facilely prepared by the low-temperature polymerization–solvent extraction strategy from EDTA-Co. The influence of Co doping on the catalytic performance of Co-CDs was explored, mainly in the following aspects: first, the pyridinic N atom content of Co-CDs significantly increased from 4.2 to 11.27 at% compared with the CDs, which indicates that the Co element in the precursor is advantageous in forming more pyridinic-N-active sites for boosting the ORR performance. Second, Co-CDs are uniformly distributed on the surface of carbon black (CB) to form Co-CDs@CB by the facile hydrothermal route, which can expose more active sites than the aggregation status. Third, the highest graphite N content of Co-CDs@CB was found, by limiting the current density of the catalyst towards the ORR. Composite nanomaterials formed by Co and CB are also used as air electrodes to manufacture high-performance zinc–air batteries. The battery has good cycle stability and realizes stable charges and discharges under different current densities. The outstanding catalytic activity of Co-CDs@CB is attributed to the Co,N synergistic effect induced by Co doping, which pioneer a new metal doping mechanism for gaining high-performance electrocatalysts.

Synergistic Interaction of MoS2 Nanoflakes on La2Zr2O7 Nanofibers for Improving Photoelectrochemical Nitrogen Reduction.

Ammonia is a suitable hydrogen carrier with each molecule accounting for up to 17.65% of hydrogen by mass. Among various potential ammonia production methods, we adopt the photoelectrochemical (PEC) technique, which uses solar energy as well as electricity to efficiently synthesize ammonia under ambient conditions. In this article, we report MoS2@La2Zr2O7 heterostructures designed by incorporating two-dimensional (2D)-MoS2 nanoflakes on La2Zr2O7 nanofibers (MoS2@LZO) as photoelectrocatalysts. The MoS2@LZO heterostructures are synthesized by a facile hydrothermal route with electrospun La2Zr2O7 nanofibers and Mo precursors. The MoS2@LZO heterostructures work synergistically to amend the drawbacks of the individual MoS2 electrocatalysts. In addition, the harmonious activity of the mixed phase of pyrochlore/defect fluorite-structured La2Zr2O7 nanofibers generates an interface that aids in increased electrocatalytic activity by enriching oxygen vacancies in the system. The MoS2@LZO electrocatalyst exhibits an enhanced Faradaic efficiency and ammonia yield of approximately 2.25% and 10.4 μg h-1 cm-2, respectively, compared to their corresponding pristine samples. Therefore, the mechanism of improving the PEC ammonia production performance by coupling oxygen-vacant sites to the 2D-semiconductor-based electrocatalysts has been achieved. This work provides a facile strategy to improve the activity of PEC catalysts by designing an efficient heterostructure interface for PEC applications.

A Facile Route to Synthesize DyF3/Bi2O3 Nanowires and Sensitive L-cysteine Sensing Properties

DyF3/Bi2O3 nanowires with orthorhombic DyF3 and triclinic Bi2O3 phases were synthesized via a facile hydrothermal route using sodium dodecyl sulfate (SDS). The composite nanowires were characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The obtained composite nanowires have the length of longer than 10 μm and diameter of about 20–100 nm. X-ray photoelectron spectroscopy confirms the composition of Dy, F, Bi and O in the composite nanowires. The formation process of the DyF3/Bi2O3 nanowires was analyzed based on the morphological and structural evolution of the products from different growth conditions. The cyclic voltammetry (CV) measurement demonstrates good electro-catalytic activity of the composite nanowires towards L-cysteine. Two pairs of CV peaks at +0.08 V, −0.43 V and −0.48 V, −0.78 V, respectively are observed at the DyF3/Bi2O3 nanowires modified glassy carbon electrode. DyF3/Bi2O3 nanowires modified glassy carbon electrode detects L-cysteine linearly over a concentration range from 0.001 to 2 mM with a detection limit of 0.25 μM. Moreover, the results show good selectivity, reproducibility and stability of the DyF3/Bi2O3 nanowires as a promising candidate for L-cysteine determination.

Facile hydrothermal synthesis of ZnFe2O4 nanostructures for high-performance supercapacitor application

Nowadays, binary transition metal oxides have attracted wide attention as an electrode material for supercapacitor applications. In this respect, we report a facile and cost-effective hydrothermal route for the synthesis of ZnFe2O4 nanostructures on nickel foam using a binder-free approach. The as-synthesized ZnFe2O4 nanostructures were characterised to study the structural, morphological and electrochemical properties. When utilized as an electrode for supercapacitor, ZnFe2O4 delivered superior specific capacitance of 552 F/g at a scan rate of 5 mV/s with a long term cyclic stability for 1000 cycles. This excellent electrochemical performance ZnFe2O4 electrode material suggests its potential use for next-generation supercapacitors.

High Performance Doped Li-Rich Li1+xMn2–xO4 Cathodes Nanoparticles Synthesized by Facile, Fast, and Efficient Microwave-Assisted Hydrothermal Route

Li-rich nanoparticles of Li1+xMn2–xO4 doped with Al, Co, or Ni are successfully synthesized using a facile, fast, and efficient microwave-assisted hydrothermal route. Synchrotron X-ray diffraction confirms the formation of the crystalline cubic spinel phase type. X-ray absorption spectroscopy analysis at the Co and Ni K- and L-edges verifies that the dopants are within the Li1+xMn2–xO4 spinel structure and are inactive during cycling in the bulk and at the surface. Moreover, we demonstrate that nanocrystallinity and cationic doping play an important role in improving the electrochemical performance with respect to LiMn2O4 microparticles. They significantly reduce the charge-transfer resistance, lower the first cycle irreversible capacity loss to 6%, and achieve a capacity retention between 85 and 90% after 380 cycles, with excellent Coulombic efficiency close to 99% without compromising the specific charge at a 5C cycling rate. Furthermore, the Mn K- and L-edges attest that after long cycling, the Mn oxidation state in the bulk differs from that at the surface caused by the Mn disproportion reaction; however, the cationic doping helps mitigate the Mn dissolution with respect to the undoped Li1+xMn2–xO4 nanoparticles, as indicated by inductively coupled plasma atomic emission spectrometry.

Liquefied petroleum gas (LPG) sensing of biphasic Cu6Sn5:SnO2 nanocomposite thin-films

This study reports the fabrication of a novel biphasic LPG sensor operable at room temperature. The biphasic Cu6Sn5:SnO2 nanocomposite is synthesized in 2 mol% and 4 mol% molar ratios through a facile hydrothermal route and fabricated into thin films. The microstructural details of these films are determined by an X-ray diffractometer (XRD). These films are further characterized for their morphology, elemental composition, optical and electrical properties employing field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectrum, UV–visible (UV–vis) spectrophotometer and four-probe technique respectively. Liquefied petroleum gas (LPG) sensing results of the nanocomposite thin films suggest enhanced sensitivity and quick response and recovery time of the Cu6Sn5 dominant nanocomposite (4 mol%) thin film at room temperature. Additionally, this particular film exhibits a better humidity and LPG sensing performance with a sensitivity of 269 MΩ/%RH and 280 MΩ/vol. % for 2.0 vol % of LPG at room temperature respectively. The improved humidity and LPG sensing of the Cu6Sn5 dominant phase nanocomposite sample may be due to the formation of crystalline structure.

Hydrothermal synthesis of manganese oxide (Mn3O4) with granule-like morphology for supercapacitor application

In the present work, we have synthesized manganese oxide (Mn3O4) nanoparticles (NPs) using the facile hydrothermal route at different pH (9, 10. 11). The effect of the pH variation on the structural and electrochemical properties of the synthesized Mn3O4 NPs have studied. Synthesized NPs are characterized using XRD, SEM, EDS, TEM, BET, cyclic voltammetry, galvanic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) for various properties. The preferred orientation of Mn3O4 growth is along the (211) plane with granule-like morphology. The Mn3O4 electrodes were fabricated and investigated for electrochemical characterizations. The capacitance of the Mn3O4 electrode was calculated from cyclic voltammetry (CV) and galvanometric charge-discharge curves at different scan rates and current densities, respectively. The specific capacitance values of the Mn3O4 electrode (pH 11) were estimated from CV and GCD viz 277 F/g and 262 F/g, respectively, with the higher capacitance retention. Charge transfer resistance was calculated from electrochemical impedance spectroscopy (EIS) measurements. The equivalent series resistance for Mn3O4 at pH 11 is around 0.015 Ω. Nanostructured MnO2 electrodes can be the potential materials for supercapacitor application.

CdS/VS2 Heterostructured Nanoparticles as Efficient Visible‐Light‐Driven Photocatalysts for Boosting Hydrogen Evolution

AbstractThe development of highly active, cost‐effective hydrogen‐evolving photocatalysts is of great significance to alleviate the escalating environmental pollution and depleting fossil fuel sources. Herein, a novel CdS/VS2 heterostructured nanoparticle is successfully synthesized for the photocatalytic hydrogen evolution reaction (HER) under visible‐light irradiation via a facile hydrothermal route. Experimental results demonstrate that VS2 can facilitate the absorption of visible light, enhance the electron transfer rate, as well as inhibit the recombination of photogenerated electron‐hole pairs on CdS photocatalyst. Moreover, the optimal CdS/VS2 (0.2 wt.%) hybrid exhibits prominent photocatalytic HER activity 16 times higher than the pristine CdS counterpart, even outperforming the 1 wt.% platinum‐loaded CdS. This work injects new impetus to explore efficient noble‐metal‐free cocatalysts of CdS photocatalyst for high‐efficiency photocatalytic H2 evolution.