For the designing of efficient redox metal-assisted electrodes, an understanding of the inclusive role of metal ions in charge storage and their influence on the electrochemical window is a prerequisite. Herein, a trimetallic boride (NiCoFe-B) nanosheet is employed as an integrated electrode in which the roles of all the metal ions are explicitly discussed through electrochemical and work function studies. The UPS study and theoretical calculations concluded the reduction of work function after insertion of Co in Ni-B framework, which increased the number of active sites and enhanced charge transfer kinetics, whereas Fe insertion resulted in an extended electrochemical window (1.35 V). To unveil the reason behind this, Fe-B is synthesized, which demonstrates the lowest work function (7.88 eV). In an integrated electrode, NiCoFe-B (NCFB), the difference in work function of Fe-B and NiCo-B results in generation of an electric field near the interface that acts as a potential barrier, further countering the external electric field and resulting in an extended potential window. Notably, a symmetric cell with the extended potential of NCFB delivers a high energy density of 45.05 Wh kg -1 at 585.52 W kg -1 and restores 86.6% of initial capacitance over 10k cycles with excellent energy delivering ability (relaxation time constant of 2.20 s). This work provides an insight into tuning the voltage plateau by combining the metal ions of different work functions in an electrode and could be used as a model to design electrodes with favourable attributes.

Polyoxometalates (POMs) are emerging redox active materials having great potential for energy storage. Normally, POMs are directly anchored to substrates, however we looked into a novel feature of POM chemistry by employing them as precursor for metal sulphide 3D microflower arrangements without the use of a template. High surface area, outstanding electrical conductivity, and exceptional structural stability are all characteristics of 2D materials like MXenes; nevertheless, their direct use is constrained by poor specific capacitance as a result of layer restacking. Transition Metal sulphides (TMDs), on the other hand, have a high surface area but a poor conductivity. Layer restacking will be prevented by an MXene-TMDs nanocomposite, which will also increase TMDs' conductivity. Here, we report MXene-TMDs nanocomposite (MV) with MXene intercalated vanadium molybdenum sulphide (VMD) microflowers using 10-molybdo-2-vanadophosphoric acid. Due to faster ionic diffusion, higher electrochemically active surface area, and more active sites, MV exhibits good electrochemical performance. Additionally, the MV parallel to MV cell offers outstanding cycling stability (96 % capacitance retention after 8000 cycles @ 2 A g(-1)) and performs well up to 0.9 V, delivering a maximum energy density of 28.96 Wh kg(-1) @ 232.35 W kg(-1). This research investigates how POMs affect the atomic ratio and morphology of final product.

Cobalt-doped and undoped zinc oxide (ZnO) nanoparticles (NPs) with different dopant concentrations were synthesized via the sol-gel method. The structural, morphological, and optical properties of the synthesized NPs were investigated using various techniques. The NPs exhibit a wurtzite structure with an average crystallite size of 20-34 nm. Change in photoluminescence (PL) spectra from dual to single band with dopants suggested decreasing surface state contribution. The PL lifetime of the 430 nm band is too short (< 10 ps), where it is multi-exponential and significantly large for the 550 nm band with a major contribution of 0.3-1.0 ns and a minor contribution of 7-9 ns and 119-126 ns. The photocatalytic performance of NPs was examined by decomposing a Congo red dye under dark, white (LED) light and UV irradiation. Among all the doped NPs, 20% Co(2+ )doped ZnO shows superior photocatalytic activity for dye degradation with a faster reaction rate constant.

Abstract The present work aims the application of extremely hazardous and life-threatening soot particles released to environment from different industrial processes. These soot materials are proposed as potential source of functionalized nano carbons for energy storage application. In this work, soot samples were collected from various sources namely automobile emission, agricultural/forest waste and industrial works; and were chemically activated using KOH to obtain heteroatom functionalized activated carbons (i.e. activated coal soot (ACS), activated diesel soot (ADS) and activated wood soot (AWS) respectively) exhibiting large BET surface area (~ 846 m2 g− 1). Morphological investigations (FESEM and HRTEM) reveals formation of interconnected granular aggregates exhibiting enormous inter-particle meso/microporous channels significant for electrolyte passage and lowering charge-transfer resistance. Structural characterizations (XRD, FTIR and Raman spectra) justify these soots having activated graphitic structures enriched with oxygen-based functionalities (e.g. -COOH, -OH, C6H5OH etc.) that impart hydrophilic character and excellent pseudocapacitive properties. Electrochemical measurements in 1 M H2SO4 affirm high capacitance values (361–440 F g− 1 at 5 mV s− 1) for soot-based electrodes bestowed by high surface area in addition to meso/microporous structure. Nevertheless, AWS║AWS cell demonstrates remarkable stability over 5000 cycles at 50 mV s− 1 owing to high carbon enriched moiety relative to ADS║ADS and ACS║ACS supercapacitors which further illustrate greater activation of electrode materials during charge/discharge caused by high content of pseudocapacitive functionalities. Variations in electrochemistry can be attributed to structural organizations of the activated soot particles and variable percentage of heteroatoms in their carbon lattices which govern overall ‘EDL plus pseudo’ performances.

Polyoxometalates (POMs) owing to their distinctive structural and highly stable redox properties are emerging as advanced electrode material for energy storage applications. The imminent concern with POMs is their long-term stability in aqueous electrolytes and conductivity which can be effectively tackled by structural engineering at molecular level. Here, we report smart assembly of polyoxometalates (POMs) and zeolitic imidazole framework (ZIF-67) as promising tool for structural modulation. The complementing dimensions of POM and ZIF-67 results in successful encapsulation of POM which not only enhances the active sites for charge storage, but also prevents the dissolution of POMs. Resulting nanocomposites were investigated in three different electrolytes where ammonium decavanadate intercalated nanocomposite (ZADV) is found to exhibit excellent electrochemical performance in 1 M Na2SO4 owing to its ordered structure with enhanced number of active sites. Further, to meet the demand of high energy density supercapacitor for modern applications, structure modulated POM (positive potential electrode) is integrated with a negative potential material "loofah sponge derived carbon (LSC) " that extends the potential from-1 to 0.6 V. The resulting integrated electrode (ZADV@LSC) displays a maximum specific capacitance of 250.1F g(-1) @ 0.8 A g(-1) with good columbic efficiency. Interestingly, ZADV@LSC||ZADV@LSC works well upto 1.6 V, delivers energy density of 19.7 Wh kg(-1) @ 586 W kg(-1) with excellent cycling stability (89% after 5000 cycles @ 1.5 A g(-1)). This work is a keystone for the upcoming studies on enhancing the performance of polyoxometalate based electrodes with improved active sites and energy density.

Two dimensional (2D) layered metal hydroxides possess unique structure and electrochemical properties. However, it is mandatory to go beyond outer surface to exploit their full potential and make the inner surface available for charge storage. Here, we demonstrate a decavanadate (DV) anion incorporation strategy to widen the gap of alpha-Co(OH)(2) nanoplates (ACH). DV is a redox active polyoxometalate so it not only work as a spacer but offers additional charge storage through pseudocapacitance. DV intercalation provides ion-buffering reservoirs to boost deep faradic redox reactions with good ionic diffusion and enhanced electrochemically active surface area. Consequently, DV-ACH nanoplates exhibits specific capacitance of 257.55 F g(-1) @ 1 A g(-1) and work well from -0.5 to 0.9 V in ecofriendly electrolyte with good reversibility coefficient. This performance is relatively much superior even in neutral electrolyte than ACH electrode studied in alkaline electrolyte, pointing towards a safer way for high performance energy storage devices. Asymmetric cell based on DV-ACH can operate up to 1.8 V and delivers a maximum energy density of 27.67 Wh kg(-1) @ 544.9 W kg(-1) with excellent cycling stability (96% after 5000 cycles). These results suggest the high efficiency of polyoxometalate modulated metal hydroxides for next generation supercapacitors. (C) 2020 Elsevier Ltd. All rights reserved.

The issue of relatively low operating potential window in aqueous supercapacitors is usually conquered by fabrication of asymmetric devices. To achieve the same in symmetric cells, electrodes with high electrochemical activity and wide working potential are needed. Herein, we report a strategy to extend the operating potential by utilizing ammonium decavanadate-holey reduced graphene oxide nanoribbons (rGONR-ADV) as hybrid electrode for supercapacitors. Besides high charge storage, use of redox-active ADV in hybrid provides a large overpotential towards water reduction, enabling wide potential window. The nano hybrids are synthesized at three different temperatures (140 degrees C, 160 degrees C, 180 degrees C) where rGONR-ADV 160 shows unsurpassed performance (1186 F g(-1) @ 1 A g(-1)) owing to the optimized synergistic effect, highly electmactive surface area and improved ionic diffusion. The rGONR-ADV 160 parallel to GONR-ADV 160 cell displays high specific capacitance (406 F g(-1) @ 0.5 A g(-1)), decent cycling stability (83% after 5000 cycles) with high energy/power density (120.2 Wh kg(-1) and 1624.14 W kg(-1)). Interestingly, this device works well up to 1.5 V in 1 M H2SO4 i.e. well beyond thermodynamic limit of water decomposition. Present study illustrates the performance of polyoxometalates based hybrid electrode for high potential aqueous supercapacitors and energy density for practical applications.

In the present investigation, the theoretical studies have been carried out for optimization of different operating parameters using various Bio-Diesel Blends. Also finally compared the experimental results over the theoretical results. The simulated programme is a versatile tool for all Stationary Internal Combustion Engines without conducting the actual experiments.

Optically active polyaniline salts have been readily prepared via enantio-selective doping the emeraldine base form of polyaniline in DMF by variety of chiral dopants via suspension method. The induction of helicity is faster by dextro chiral agents than their corresponding laevo enantiomer because of the lesser energy requirement for structural deformation in dextro. CD spectra confirm the incorporation of chiral anion in PANI and helicity induction in visible region. XRD data show that PANI-(+)-HCSA and PANI-Dibenzoyl-D-Tr have orthorhombic symmetry with space group pbcn while the Le-Bail fit of the powder XRD pattern of PANI-(+)-Tr and PANI-(+)- Mnd confirmed triclinic symmetry with space group P−1. The powder X-ray diffraction patterns reveal that PANI is amorphous in nature while chiral acid doped PANI has remarkable crystallinity. SEM micrographs reveal the fibrous morphology of PANI before doping and strong coiling between the fibers of PANI after doping with chiral acids.

Climate change resulting from increased levels of atmospheric greenhouse gases such as carbon dioxide could, many believe, be a serious threat to the environment and the world economy. A significant portion of these CO2 emissions are emitted into the atmosphere when hydrocarbon fuels are burned to produce energy, particularly in the power sector. One emerging technology or set of technologies that has been proposed to mitigate future CO2 emissions is carbon capture and storage (CCS). Carbon dioxide capture is generally estimated to represent three-fourths of the total cost of a carbon capture, storage, transport, and sequestration system. Evolutionary improvements in existing CO2 capture systems and revolutionary new capture and sequestration concepts will be needed to bring carbon capture costs down. The main objective is to reduce the energy penalty of the Post combustion CO2 capture system. The scope for decreasing energy consumption in compressor and re-boiler unit has been identified in this project. Using the technique of heat integration and heat recovery the compressor power has been reduced by 13% and the net re-boiler duty reduced by 39%.