Cost-effective Hydrothermal Process Research Articles

Hydrothermal synthesis of melamine-based porous organic polymer for the advanced adsorption of iodine

The release of carbon dioxide into the atmosphere from the combustion of fossil fuels to produce energy contributes to severe climate change. Transitioning from fossil fuels to nuclear energy, which is free of carbon emissions, presents its own set of challenges, particularly the potential release of radioactive iodine in handling nuclear waste and in the instance of a nuclear accident. The ongoing research aimed to harness the advantages of porous organic polymers to capture iodine generated during nuclear fission by synthesizing them in an environmentally friendly and cost-effective hydrothermal process. Herein, a melamine-based porous organic polymer (MPOP-4), possessing reliable thermal and chemical stability, highly porous (SABET=195.48 m2/g), designed for iodine capture, is reported. The synthesis of MPOP-4 using melamine and uracil as basic building blocks showed high iodine vapor capture capacities in various media (6.30 g/g at 80 °C, 4833.15 mg/g from aqueous solution, and 1.98 g/g at 25 °C), accompanied by good regeneration ability. A significant abundance of nitrogen content, conjugated π-electron arrangement, and porous network make it an efficient iodine adsorbent. This study suggests the green nature (metal-free) of MPOP-4 and its ability to adsorb iodine.

Green synthesis of almond peel-mediated lignin nanoparticles as a potential photocatalytic agent with cytotoxicity response

In this study, we innovatively explored the utilization of almond peel to synthesize lignin-NPs through a singular and cost-effective hydrothermal process. The research delved into a comprehensive analysis of the structural and optical characteristics of the synthesized lignin-NPs through a suite of techniques including FT-IR, XRD, TEM, EDX/FESEM, UV–Vis, and Photoluminescence (PL). UV–Vis spectra showed the maximum wavelength at 280 nm, confirming the NPs’ synthesis. According to PL spectroscopy, lignin-NPs emitted fluorescent light at 551 nm. Also, FTIR and XRD patterns confirmed nanoparticle synthesis with crystallinestructure. The TEM and FESEM images showed spherical morphology with an average size of 9.97 nm. The stability of nanoparticles was assessed utilizing zeta potential analysis (−23 mV) and DLS showing a PDI around 0.2. The cytotoxic effect of lignin-NPs was investigated on Huh-7 and normal L929 cell lines using the MTT assay and the result showed that no significant toxicity was observed on normal L929 cells after 48 h, but IC50 value for cancer Huh-7 cells was about 597.2 µg/mL. A photocatalytic test revealed that lignin-NPs degrade Methylene Blue (90 %, MB), Eriochrome Black T (89 %, EBT), and Rhodamine B (85 %, RhB) pigments under UVA light after 60 min.

Highly selective oxidation of biomass-derived alcohols and aromatic alcohols to aldehydes over Ti3C2-TiO2 nanocomposites under visible light

Ti3C2Tx is a two-dimensional (2D) material belonging to the MXenes family. It has a unique combination of functional features that make it appropriate for a wide range of fascinating applications, including supercapacitors, batteries, strain sensors, photocatalysis, and more. In this study, we report a synthesis of Ti3C2-TiO2 nanocomposites with tight interfacial contact that has been successfully fabricated by in situ development of TiO2 nanoparticles (NPs) on the surface of Ti3C2Tx nanosheets (NSs) via a simple and cost-effective hydrothermal process. The catalysts are well characterized by various sophisticated techniques, including X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), Brunauer-Emmett-Teller (BET), CHI660E electrochemical workstation, and HRTEM. The photocatalytic performance of pure Ti3C2Tx, Ti3C2-TiO2 (MT1), and Ti3C2-TiO2 (MT5) nanocomposites was evaluated by highly selective photo-oxidation of biomass-derived furfuryl alcohol (FA), cinnamyl alcohol, vanillin alcohol, and various aromatic alcohols to the corresponding aldehyde with >99% selectivity for all the alcohol substrates under visible light (385–740 nm). Photocatalytic oxidation results revealed that Ti3C2-TiO2 (MT5) has superior photocatalytic activity than Ti3C2-TiO2 (MT1) and pure Ti3C2Tx NSs. The exceptional photocatalytic activity was attributed to the composite's unique morphology and characteristics.

Porous cobalt phosphide nanoflakes supported on ordered mesoporous carbon for superior electrochemical performance supercapacitor and hydrogen evolution reaction

In this study, we synthesized cobalt phosphate flake-like nanostructures anchored to the OMC matrix using a simple and cost-effective hydrothermal process followed by an environmentally friendly phosphidation process. The physicochemical characterization of the CoP@OMC composite indicated that the porous CoP nanoflakes made up of bundles of ultrathin nanosheets with an approximate thickness of 30 nm are anchored on rod-like hexagonal OMC with a diameter of 110–140 nm, allowing remarkable enhancement of mesoporosity and active surface area. The CoP@OMC composite was employed as a new material for modification of electrode surface used in supercapacitor and hydrogen evolution reaction (HER). Interestingly, CoP@OMC acquired a specific capacitance of 3182 Fg−1 at current density of 1 A g−1, in 6 M KOH. Asymmetrical CoP@OMC//CB cell showed a capacity of 194 Fg−1 at the current density of 1 A g−1 with a maximum energy density of 77.9 Wh kg−1 and a power density of 17 kW kg−1. CoP@OMC composite also showed an excellent HER performance with only 111 mV overpotential to drive a current density of 10 mA cm−2 and a low Tafel slope of 43.8 mV dec−1 in 1 M KOH. Therefore, CoP(OMC) as an environmentally friendly material with high efficiency and significant catalytic / electronic properties is expected to be a good candidate for future energy storage & conversion systems.

Nb2O5 Microcolumns for Ethanol Sensing.

Pseudohexagonal Nb2O5 microcolumns spanning a size range of 50 to 610 nm were synthesized utilizing a cost-effective hydrothermal process (maintained at 180 °C for 30 min), followed by a subsequent calcination step at 500 °C for 3 h. Raman spectroscopy analysis unveiled three distinct reflection peaks at 220.04 cm-1, 602.01 cm-1, and 735.3 cm-1, indicative of the pseudohexagonal crystal lattice of Nb2O5. The HRTEM characterization confirmed the inter-lattice distance of 1.8 Å for the 110 plain and 3.17 Å for the 100 plain. The conductometry sensors were fabricated by drop-casting a dispersion of Nb2O5 microcolumns, in ethanol, on Pt electrodes. The fabricated sensors exhibited excellent selectivity in detecting C2H5OH (ΔG/G = 2.51 for 10 ppm C2H5OH) when compared to a variety of tested gases, including CO, CO2, NO2, H2, H2S, and C3H6O. The optimal operating temperature for this selective detection was determined to be 500 °C in a dry air environment. Moreover, the sensors demonstrated exceptional repeatability over the course of three testing cycles and displayed strong humidity resistance, even when exposed to 90% relative humidity. This excellent humidity resistance gas sensing property can be attributed to their nanoporous nature and elevated operating temperature.

Ag-doped NiS nanocubes: Tailoring properties for optimal antibacterial performance

This study explores the synthesis of silver-doped nickel sulfide nano-cubes (Ni1-xAgxS: x= 0.00, 0.04, and 0.08) through a cost-effective hydrothermal process. X-ray diffraction analysis assured the presence of hexagonal NiS nanoparticles with fine crystallinity, with an estimated crystallite size of Ag-doped NiS ranges from 21.19 to 15.69 nm. A reduction in crystallite size was observed while including Ag ions along with enhancement in lattice constants for ‘a’ and ‘b’ from 3.416 Å to 3.424 Å and ‘c’ from 5.280 to 5.286 Å. The scanning electron microscopic images displayed cubic shaped agglomerated particles, that seemed quite suitable for antibacterial activity. The materials exhibit semiconducting behavior, as evidenced by increased direct current electrical conductivity with the rise in temperature. With increased silver content, the direct current electrical conductivity rises, and activation energy decreases from 0.246 to 0.213 eV. Dielectric characteristics, including dielectric constant, dielectric loss, and AC electrical conductivity, show a positive correlation with temperature, and all the aforementioned values elevates with systematic variation in Ag doping. The Agar well-diffusion method evaluates the antibacterial activity of un-doped and Ag-doped NiS nano-cubes against various pathogens, such as Gram-positive bacteria (M. luteus and S. aureus) and Gram-negative bacteria (E. coli and S. enterica), and significant inhibitory zones against all tested microbes, confirming the potential antibacterial efficacy. The Ag-doped NiS exhibited enhanced antibacterial efficiency. This research highlights Ag-doped NiS nano-cubes attributed with multifaceted functionalities, making them promising candidates for particular usage such as targeted drug delivery systems, antibacterial powder, wastewater treatment and pharmaceutical applications.

Hydrothermal synthesis of an MoS2/MnO2 nanocomposite: a unique 3D-nanoflower/1D-nanorod structure for high-performance energy storage applications

In this study, an MoS2/MnO2 nanocomposite electrode with a novel 3D nanoflower/1D nanorod architecture is effectively synthesized using a straightforward, cost-effective hydrothermal process.

Construction of Z-scheme heterojunction TiO2-ZnO@Oxygen-doped gC3N4 composite for enhancing H2O2 photoproduction and removal of pharmaceutical pollutants under visible light

In this study, the heterojunction photocatalyst of titanium dioxide-zinc oxide@oxygen-doped graphitic carbon nitride (TiO2-ZnO@OCN (TZ@OCN)) was synthesized using a simple and cost-effective hydrothermal self-assembly process. Characterization of the fabricated materials revealed that the incorporation of TiO2 and ZnO as inherent semiconductors along with the oxygen doping has effectively broadened the absorption spectrum of gC3N4, which can promote the electron generation and provide more active sites for O2 and H+ adsorption. It is noteworthy that the mentioned structure modification resulted in a superior H2O2 production rate among gC3N4-based photocatalysts with up to 3.11 mM.g−1 under visible light irradiation. Moreover, a valence band shifting from 1.57 to 2.91 eV upon doping oxygen atoms also elucidated the participation of active species in the photocatalytic degradation of ciprofloxacin (99.7 %, k = 0.030 min−1) and tetracyline (94.6 %, k = 0.017 min−1), in which superoxide radicals (•O2−) were shown to play a major role in removing the antibiotic. Besides, a Z-scheme heterojunction mechanism is additionally suggested, demonstrating the effectiveness of electron-hole pair splitting in the oxidation of antibiotics. Conclusively, the results show a novel and feasible modification pathway to enhance the photocatalytic activities of gC3N4 and other advanced semiconductor catalysts, especially for eliminating antibiotics and generating H2O2 within aqueous media.

Electrochemical Determination of 17-β-Estradiol Using a Glassy Carbon Electrode Modified with α-Fe2O3 Nanoparticles Supported on Carbon Nanotubes.

In this study, a novel electrochemical assay for determining 17-β-estradiol (E2) was proposed. The approach involves modifying a glassy carbon electrode (GCE) with a nanocomposite consisting of α-Fe2O3 nanoparticles supported on carbon nanotubes (CNTs)-denoted as α-Fe2O3-CNT/GCE. The synthesis of the α-Fe2O3-CNT nanocomposite was achieved through a simple and cost-effective hydrothermal process. Morphological and chemical characterization were conducted using scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The presence of the α-Fe2O3-CNT film on the GCE surface resulted in an enhanced electrochemical response to E2, preventing electrode surface fouling and mitigating the decrease in peak current intensity during E2 oxidation. These outcomes substantiate the rationale behind the GCE modification. After the optimization of experimental conditions, E2 was determined by the square wave voltammetry technique using 0.1 mol L-1 KCl solution (pH = 7.0) with 20% ethanol as a supporting electrolyte. A linear concentration range of 5.0-100.0 nmol L-1 and a low limit of detection of 4.4 nmol L-1 were obtained. The electroanalytical method using α-Fe2O3-CNT/GCE was applied for E2 determination in pharmaceutical, lake water, and synthetic urine samples. The obtained results were attested by recovery tests and by high-performance liquid chromatography as a comparative technique at a 95% confidence level. Thus, the developed electrochemical sensor is simple and fast to obtain, presents high accuracy, and is viable for determining E2 in routine analysis.

An easy CTAB-assisted path towards bayberry-like Ni–Co–Mn ternary hydroxide with enhancing supercapacitor performance

In this study, we synthesized a bayberry-like Ni–Co–Mn ternary hydroxide with a secondary nanoneedle structure using a modified and cost-effective hydrothermal process assisted by the surfactant cetyltrimethylammonium bromide (CTAB). The incorporation of CTAB and graphene in the preparation process significantly enhances the electrochemical performance of NiCoMn–OH. The achieved results are truly impressive, with a high specific capacity of 1450 ​F ​g−1 and an outstanding capacity retention of 52.57% over 5000 cycles. The superior performance could be attributed to the specific bayberry-like microstructure with high effective specific surface area, which allowed for facile and rapid transport of ions and electrons. Moreover, the synergistic effect of CTAB and graphene proved to be crucial in stabilizing the Co2+ and Mn2+ ions within the ternary hydroxide structure. We developed a hybrid capacitor using a NiCoMn–OH-CTAB/Graphene composite electrode and an active electrode, which delivered a superior energy density of 50.79 ​Wh kg−1 at a power density of 400 ​W ​kg−1 and a cycling stability of 60.37% after 10000 cycles. These results indicate that the NiCoMn–OH-CTAB/Graphene composite electrode has great potential as an electrode material for energy storage devices.

Preparation and Characterization of ZnO NWs/Graphene Nanocomposite as an Effective Photoanode Electrode for Improving the Performance of the Dye-Sensitized Solar Cells

In the present study, DSSCs were fabricated using pure ZnO NWs and ZnO NWs/Graphene nanocomposite as photoelectrodes. Graphene was incorporated into pure ZnO NWs through a cost-effective Hydrothermal Process to act as an electrical charge carrier. J-V curve of prepared nanocomposite was recorded with a light intensity of 100 mW.cm-2. The created nanocomposites were thoroughly investigated by using different electrical and structural characterization techniques such as SEM, XRD, and J-V characteristics. According to SEM examination, the ZnO NWs/graphene composite-based electrode has more porosity than the electrode made using pure ZnO NWs, which will increase the surface area and the amount of dye that can be absorbed. From the graphene advantages the reduced internal resistance and electron recombination loss, these properties allow electrons to transfer to the collection electrode efficiently. Based on these benefits, the ZnO NWs/Graphene nanocomposite photoanode with thickness of 965.11 nm that was used in the DSSC2 was demonstrated a Jsc of 19.50 mA.cm-2 and conversion efficiency of 9.829053%, which opposite to the result of the DSSC1 without graphene. These results can be encouraged for future improved optoelectronic devices.

The effect of phosphorus and nitrogen dopants on structural, microstructural, and electrochemical characteristics of 3D reduced graphene oxide as an efficient supercapacitor electrode material

Supercapacitors are environmentally friendly and safe energy storage devices for diverse applications. The electrode material's structural, microstructural, and electrochemical properties are crucial determinants of supercapacitor capacity. One effective method to improve electrode performance is introducing doping heteroatoms or synthesizing composite materials. In this study, three-dimensional reduced graphene oxide (3D rGO) doped with Phosphorus, Nitrogen, or both (N/P co-doped) was synthesized for high-efficiency, supercapacitors using a facile, fast, and cost-effective hydrothermal process. The hydrothermal reduction of graphene oxide involved substituting Phosphorus and Nitrogen elements with carbon atoms. Moreover, the effect of dopants on structural and microstructural characteristics of 3D rGO was evaluated using different techniques, and the electrochemical characteristics were evaluated by cyclic voltammetric (CV) analysis, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). The specific capacitance of 3DN/PrGO on Ni foam reached 648 F g−1 at 1 Ag−1, in a voltage range of −0.6 –0.6 V (vs. Ag/AgCl), using 6 M KOH as the electrolyte. High energy density and power density of 6.1 wh/kg and 513 w/kg were obtained, respectively. The stability test was also conducted, and appropriate stability over 100 charging and discharging cycles was observed. The considerable performances are mainly due to the combined effect of pseudocapacitive properties of Nitrogen and Phosphorus dopants, improved wettability, and the porous structure of 3D rGO, which provides suitable electroactive sites and simplifies the electron/ion transfer for the electrochemical reactions.

The removal enhancement of organic contaminations and optimization of the photocatalytic efficiency by Box-Behnken design using ZnO-TiO2/porous graphene aerogel.

In this study, zinc oxide-titanium dioxide/graphene aerogel (ZnO-TiO2/GA) was successfully synthesized through a simple and cost-effective hydrothermal self-assembly process. Besides, the surface response model and the experimental design according to the Box-Behnken model were selected to determine the optimal removal efficiency for crystal violet (CV) dye and para-nitrophenol (p-NP) phenolic compound. According to the obtained results, the highest degradation efficiency for CV dye of 99.6% was obtained under the following conditions: pH 6.7, CV concentration of 23.0 mg/L, and catalyst dose of 0.30 g/L. For p-NP, the degradation efficiency reached 99.1% under the following conditions: H2O2 volume of 1.25 mL, pH 6.8, and catalyst dose of 0.35 g/L. Therewithal, kinetic models of adsorption-photodegradation, thermodynamic adsorption, and free radical scavenging experiments were also investigated to propose the specific mechanisms involving the removal of CV dye and p-NP. According to the aforementioned results, the study provided a resulting ternary nanocomposite with great removal performance for water pollutants via the synergetic effects of adsorption and photodegradation processes.

Intercalation of two-dimensional graphene oxide in WO3 nanoflowers for NO2 sensing

Chemiresistive WO3-GO (WG) nanohybrid sensors were designed by a cost-effective hydrothermal process. The structure, morphology, composition and surface features of the prepared WG nanohybrids were explored by an array of analytical techniques, such as X-ray diffractometry (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM) and Brunauer–Emmett–Teller (BET) surface profiling. The gas sensing performance of the WG nanohybrids reveals that the small amount of GO significantly impacts the sensor performance. The enhanced gas sensing performance of the WG nanohybrid sensor with a GO content of 3 weight% exhibits an excellent response to 100 ppm of NO2, attaining 239%, which is nearly fourfold higher than that of pristine WO3 (61%) at 150 °C, and shows outstanding selectivity, reproducibility and stability (84.5%). Impedance spectroscopy was employed to understand the interaction between the NO2 gas molecules and the WG nanohybrid.

Facile synthesis of accordion-like porous carbon from waste PET bottles-based MIL-53(Al) and its application for high-performance Zn-ion capacitor

It is of great scientific and economic value to recycle waste poly (ethylene terephthalate) (PET) into high-value PET-based metal organic frameworks (MOFs) and further convert it into porous carbon for green energy storage applications. In the present study, a facile and cost-effective hydrothermal process was developed to direct recycle waste PET bottles into MIL-53(Al) with a 100% conversation, then the MOF-derived porous carbon was assembled into electrodes for high-performance supercapacitors. The results indicated that the as-synthesized carbon exhibited high SSA of 1712 m2 g−1 and unique accordion-like structure with hierarchical porosity. Benefit to these advantageous characters, the assembled three-electrode supercapacitor displayed high specific capacitances of 391 F g−1 at the current density of 0.5 A g−1 and good rate capability of 73.6% capacitance retention at 20 A g−1 in 6 mol L−1 KOH electrolyte. Furthermore, the assembled zinc ion capacitor still revealed outstanding capacitance of 335 F g−1 at 0.1 A g−1, excellent cycling stability of 92.2% capacitance retention after 10 000 cycles and ultra-high energy density of 150.3 Wh kg−1 at power density of 90 W kg−1 in 3 mol L−1 ZnSO4 electrolyte. It is believed that the current work provides a facile and effective strategy to recycle PET waste into high-valuable MOF, and further expands the applications of MOF-derived carbons for high-performance energy storage devices, so it is conducive to both pollution alleviation and sustainable economic development.

Effect of Cu Doping on ZnO Nanoparticles as a Photocatalyst for the Removal of Organic Wastewater.

Environmental problems with chemical and biological water pollution have become a major concern for society. Providing people with safe and affordable water is a grand challenge of the 21st century. The study investigates the photocatalytic degradation capabilities of hydrothermally prepared pure and Cu-doped ZnO nanoparticles (NPs) for the elimination of dye pollutants. A simple, cost-effective hydrothermal process is employed to synthesize the Cu-doped ZnO NPs. The photocatalytic dye degradation activity of the synthesized Cu-doped ZnO NPs is tested by using methylene blue (MB) dye. In addition, the parameters that affect photodegradation efficiency, such as catalyst concentration, starting potential of hydrogen (pH), and dye concentration, were also assessed. The dye degradation is found to be directly proportional to the irradiation time, as 94% of the MB dye is degraded in 2 hrs. Similarly, the dye degradation shows an inverse relation to the MB dye concentration, as the degradation reduced from 94% to 20% when the MB concentration increases from 5 ppm to 80 ppm. The synthesized cost-effective and environmentally friendly Cu-doped ZnO NPs exhibit improved photocatalytic activity against MB dye and can therefore be employed in wastewater treatment materials.

Efficiency Enhancement of Electro-Adsorption Desalination Using Iron Oxide Nanoparticle-Incorporated Activated Carbon Nanocomposite.

Capacitive deionization (CDI) technology is currently considered a potential candidate for brackish water desalination. In this study, we designed iron oxide nanoparticle-incorporated activated carbon (AC/Fe2O3) via a facile and cost-effective hydrothermal process. The as-synthesized material was characterized using several techniques and tested as electrodes in CDI applications. We found that the distinctive properties of the AC/Fe2O3 electrode, i.e., high wettability, high surface area, unique structural morphology, and high conductivity, resulted in promising CDI performance. The electrosorptive capacity of the AC/Fe2O3 nanocomposite reached 6.76 mg g−1 in the CDI process, with a high specific capacitance of 1157.5 F g−1 at 10 mV s−1 in a 1 M NaCl electrolyte. This study confirms the potential use of AC/Fe2O3 nanocomposites as viable electrode materials in CDI and other electrochemical applications.

Facile synthesis of iron[sbnd]nickel[sbnd]cobalt ternary oxide (FNCO) mesoporous nanowires as electrode material for supercapacitor application

Transition Metal Oxides have drawn significant attention due to their reversible chemical redox reaction and long-life stability. Inexorable agglomeration and shrinkage/expansion of transition metal oxides in the nanosize regime have a noticeable effect on their electrochemical properties. Here in this work, mesoporous nanowires (NWs) with a typical composition of iron-nickel-cobalt ternary oxide (FNCO) are synthesized using a simple, facile and cost-effective hydrothermal process followed by furnace annealing. These NWs are then extensively investigated as an electrode material for supercapacitor application. To compare the electrochemical properties, nanowires of nickel-cobalt oxide (NCO), iron-cobalt oxide (FCO) and cobalt oxide (CO) were also produced by following the same protocol. The FNCO NWs are found to overcome the shortcomings in the electrochemical energy storage devices by exhibiting higher values of specific capacitance (2197 Fg-1) and energy density (109 Whkg−1) at 1 Ag-1 current rate. Moreover, the FNCO NWs also showed a cyclic charge/discharge stability of 96% even up to 20,000 cycles. Furthermore, a FNCO//graphene asymmetric device, fabricated with FNCO NWs and graphene as positive and negative electrodes, respectively, which exhibit high energy density (47 Whkg−1), power density (375 Wkg-1) and excellent capacitance retention (86%) after 15,000 cycles.

Hierarchical MnNiCo ternary metal oxide/graphene nanoplatelets composites as high rated electrode material for supercapacitors

For achieving a higher supercapacitor performance, electrode material with high surface area and conductivity such as graphene, graphene nanoplatelets (GNP), and carbon nanotubes along with Transition Metal oxides (TMO) can be used. Herein, the composite of graphene nanoplatelets with ternary metal oxide of manganese, nickel, and cobalt (MNC) is synthesized through a facile cost-effective hydrothermal process and its compositional, morphological, and electrochemical properties are investigated. As-synthesized MNC-GNP composite showed excellent electrochemical properties owing to the high porosity offered by graphene nanoplatelets and synergistic effects produced by individual components of the composite. For comparative studies, ternary oxide MNC was prepared by the same hydrothermal route. The cubic structure of the MNC-GNP composite is confirmed by X-ray diffraction (XRD). Scanning Electron Microscope (SEM) showed distinct hierarchical dendritic structures which showed an increase in density by the addition of graphene nanoplatelets. Electrochemical testing revealed that MNC-GNP exhibited an enhanced specific capacity of 605 mAh g-1 which is higher compared to MNC which exhibited 243 mAh g-1 at a current density of 2 mV s-1. GCD also depicted an increased charge-discharge time in the case of MNC-GNP as compared to its counterpart. MNC-GNP has also shown charge stability up to 99.5 % of capacity retention up to 1000 cycles. Hence, synthesized composite shows to be an effective electrode material for supercapacitors owing to enhanced electrochemical properties.

Hierarchical 3D Oxygenated Cobalt Molybdenum Selenide Nanosheets as Robust Trifunctional Catalyst for Water Splitting and Zinc-Air Batteries.

The development of hierarchical nanostructures with highly active and durable multifunctional catalysts has a new significance in the context of new energy technologies of water splitting and metal-air batteries. Herein, a strategy is demonstrated to construct a 3D hierarchical oxygenated cobalt molybdenum selenide (O-Co1- x Mox Se2 ) series with attractive nanoarchitectures, which are fabricated by a simple and cost-effective hydrothermal process followed by an exclusive ion-exchange process. Owing to its highly electroactive sites with numerous nanoporous networks and plentiful oxygen vacancies, the optimal O-Co0.5 Mo0.5 Se2 could catalyze the hydrogen evolution reaction and oxygen evolution reaction effectively with a low overpotential of ≈102 and 189 mV, at a current density of 10 mA cm-2 , respectively, and exceptional durability. Most importantly, the O-Co0.5 Mo0.5 Se2 ||O-Co0.5 Mo0.5 Se2 water splitting device only entails a voltage of ≈1.53 V at a current density of 10 mA cm-2 , which is much better than benchmark Pt/C||RuO2 (≈1.56 V). Furthermore, O-Co0.5 Mo0.5 Se2 air cathode-based zinc-air batteries exhibit an excellent power density of 120.28 mW cm-2 and exceptional cycling stability for 60 h, superior to those of state-of-art Pt/C+RuO2 pair-based zinc-air batteries. The present study provides a strategy to design hierarchical 3D oxygenated bimetallic selenide-based multifunctional catalysts for energy conversion and storage systems.