Hydroxide Electrolyte Research Articles

Investigation on structural, optical and electrochemical behavior of NiO/ZnMn2O4 ternary nanocomposites via two-step synthesis approach for supercapacitor application

The present investigation deals with the synthesis of nickel oxide (NiO)/zinc manganite (ZnMn2O4) nanocomposites (NCs) by a two-step approach. The powder X-ray diffraction (PXRD) pattern revealed the existence of face-centered cubic (FCC) phase of NiO and tetragonal rutile phase structure of ZnMn2O4 in NiO/ZnMn2O4 NCs. The optical properties of NiO/ZnMn2O4NCs have been investigated by the UV-diffuse reflectance Spectroscopy (UV-DRS) and photoluminescence (PL) spectral analysis. The surface morphology and elemental composition of NiO/ZnMn2O4NCs was investigated by field emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectrum (EDX) analysis. The surface area and the nature of porosity of the samples were analyzed using Brunauer–Emmett–Teller (BET) method. The electrochemical properties were investigated from the cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. In 0.5 M potassium hydroxide (KOH) electrolyte solution, NiO/ZnMn2O4NCs exhibited higher specific capacitance of 886 F/g at a current density of 1Ag−1 with high cyclic stability over 1000 charge–discharging cycles. Thus, the result demonstrates that the prepared NiO/ZnMn2O4NCs is a promising electrode material for future energy-storage devices.

NiCo Metal-Organic Framework and Porous Carbon Interlayer-Based Supercapacitors Integrated with a Solar Cell for a Stand-Alone Power Supply System.

Nickel cobalt-metal-organic framework (NiCo-MOF), with a semihollow spherical morphology composed of rhombic dodecahedron nanostructures, was synthesized using a scalable and facile wet chemical route. Such a structure endowed the material with open pores, which enabled rapid ion ingress and egress, and the high effective surface area of the MOF allowed the uptake and release of a large number of electrolyte ions during charge-discharge. By combining this NiCo-MOF cathode with a highly porous carbon (PC) anode (derived from the naturally grown and abundantly available bio-waste, namely, palm kernel shells), the resulting PC//NiCo-MOF supercapacitor using an aqueous potassium hydroxide (KOH) electrolyte delivered a capacitance of 134 F g-1, energy and power densities of 24 Wh kg-1 and 0.8 kW kg-1 at 1 A g-1, respectively, over an operational voltage window of 1.6 V. By employing thin interlayers of PC coated over a Whatman filter paper (PC@FP), the modified supercapacitor configuration of PC/PC@FP//PC@FP/NiCo-MOF delivered greatly enhanced performance. This cell delivered a capacitance of 520 F g-1 and an energy density of 92 Wh kg-1, improved by nearly 4-fold, compared to the analogous supercapacitor without the interlayers (at the same power and current densities and voltage window), thus evidencing the role of the cost-effective, electrically conducting porous carbon interlayers in amplifying the supercapacitor's energy storage capabilities. Further, illumination of white light-emitting diodes (LEDs) using a three-series configuration and the photocharging of this supercapacitor with a solution-processed solar cell are also demonstrated. The latter confirms its ability to function as a stand-alone power supply system for electronic/computing devices, which can even operate under medium lighting conditions.

Electrospun fibrous active bimetallic electrocatalyst for hydrogen evolution

Fabricating earth-abundant bifunctional water splitting electrocatalysts with high efficiencies to replace noble metal-based Pt and IrO2 catalysts is in great demand for the development of clean energy conversion technologies. Molybdenum disulfide (MoS2) nanostructures have attracted much attention as promising material for hydrogen evolution reaction (HER). The production of hydrogen gas by help of potential efficient earth abundant metal oxides, and stable electrolysis seems a promising for hydrogen evolution reaction pathway in 1 M potassium hydroxide electrolyte media is a hot research topic in the field for clean energy conversion, renewable energies and storage. Here we propose asystem composed NiO nanostructures and MoS2 deposited on (MoS2@NiO). Here, by hydrothermal method NiO prepared and MoS2@NiO by an electrospinning technique complex, can be used as catalyst to produce a large amount of hydrogen gas bubbles. The NiO nanostructures composite having highest synergistic behavior fully and covered by the MoS2. For the MoS2@NiO nano composite catalyst, experiment applied in 1 M KOH for the production of hydrogen evolution reaction which exhibits distinct properties from the bulk material. Overpotential values recorded low 406 mV and current density 10 mA cm−2 measured. Co-catalysts characterized by using different techniques for deep study as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Owing to their unique structure, as-prepared nanocomposite exhibited enhanced catalytic performance for HER due to high electroactive surface area and swift electron transfer kinetics. Based on the HER polarization curves at low potential electrochemical to examine the effects of intercalants HER catalytic efficiency. Our findings establish low Tafel slope (44 mV/decade) and the catalyst stable for at least 13 h. This simple exploitation of MoS2@NiO composite catalysts depending on the intended application of their electrochemistry.

Hybrid high-concentration electrolyte significantly strengthens the practicability of alkaline aluminum-air battery

Alkaline aluminum-air batteries show great potential for energy storage applications because of their high theoretical energy density and low cost. However, they are suffering from severe anodic self-corrosion and the gelation of electrolyte which greatly reduce the practical energy density and shelf life. Herein, we firstly construct an efficient high-energy alkaline Al-air battery based on high-concentration potassium acetate-potassium hydroxide electrolyte and prototype optimization. The self-corrosion of Al anode is greatly suppressed owing to the special hydrate structure in such electrolyte. The Al-air battery with optimum electrolyte demonstrates remarkable increased discharge capacity of 2324 mAh g−1, and the constructed miniaturized Al-air battery enables an outstanding system energy density of 436.1 ​Wh kg−1 (compared with 85.8 ​Wh kg−1 of normal electrolyte) after integrating a discharge product removing system. This work opens up a new direction for the practical realization of high-energy, low-cost, and high-efficiency alkaline Al-air battery and other aqueous metal-air batteries.

Engineering the performance of negative electrode for supercapacitor by polyaniline coated Fe3O4 nanoparticles enables high stability up to 25,000 cycles

Supercapacitors (SCs) have proven remarkable interest in portable digital devices because of their long life span and high power densities. However, low energy densities of SCs hindered their applications due to the lack of high-performance negative electrode materials. In this work, we demonstrated the successful surface engineering of iron oxide nanoparticles (Fe3O4-NPs) by polyaniline (PANI) coating through a facile low-temperature hydrothermal method. The polyaniline coated iron oxide nanoparticles (Fe3O4/PANI-NPs) were characterized by a series of techniques including XRD, FT-IR, RAMAN, XPS, TGA, BET, SEM, and TEM. Fe3O4-NPs and Fe3O4/PANI-NPs are investigated as negative electrode materials for SCs in basic potassium hydroxide (KOH) electrolyte. The Fe3O4/PANI-NPs sample possesses specific capacitance of 1669.18 F g−1 while Fe3O4-NPs exhibits 1351.13 F g−1 at 1 A g−1 at identical conditions. The Fe3O4/PANI-NPs sample exhibits remarkable electrochemical cycling performance (96.5%) over pristine Fe3O4-NPs (92%) at high current density of 15 A g−1 by exceeding the 25,000 times charge/discharge cycles. The PANI coating not only offers a strong shell to avoid degradation of the material but also contributes to enhancing the capacitance with outstanding stability. Furthermore, we analyzed the charge storage contributions by implementing the power's law and interestingly Fe3O4/PANI-NPs sample exhibits high capacitive type storage (85% capacitive at 10 mVs−1). Based on our experiments, Fe3O4/PANI-NPs shows exceptional high electrochemical results in basic electrolyte with excellent stability and surpass most of recently reported work based on the iron oxides and their composites. Therefore, the proposed strategy can be applied to fabricate the high-performance negative electrode materials for supercapacitors.

Organometallic redox flow batteries using iron triethanolamine and cobalt triethanolamine complexes

Organometallic complexes consisting of iron- and cobalt-triethanolamine ligand (Fe (TEA) and Co(TEA)) are proposed as redox couple of aqueous redox flow battery (ARFB). Fe (TEA) and Co(TEA) are dissolved in sodium hydroxide (NaOH) electrolyte, while their chemical stability and electrochemical reactivity are quantitatively characterized. As a result, the chemical stability of Co(TEA) is degraded for multiple charge/discharge cycle test due to the deformation of unchelated TEAs by the chemical reaction with hydroxyl ion (OH−) and the catalytic effect of Co(TEA). To address the issue, the ratio of Co to TEA and the concentration of NaOH are manipulated. When the ratio is 1:1, the redox reactivity of Co(TEA) is improved because the amount of unchelated TEAs that is a reason for lowering its redox reactivity is minimized, while 4 M NaOH is proper to supply enough amount of OH−, preserving its chemical structure and reducing mass transfer retardation. Regarding Fe (TEA), with 1:2.5 ratio of Fe to TEA in 4 M NaOH, the stability and performance of Fe (TEA) are best. Performance of ARFB using 1:2.5 Fe (TEA) and 1:1 Co(TEA) shows excellent results of high charge and energy efficiencies of 99% and 62% at 40 mA cm−2, and high power density of 35 mWcm−2.

Surface assembly of Fe3O4 nanodiscs embedded in reduced graphene oxide as a high-performance negative electrode for supercapacitors

In this work, iron oxide (Fe3O4) nanodiscs and anchored on reduced graphene oxide (rGO) as a nanocomposite (Fe3O4/rGO) have been fabricated through a surface, scalable hydrothermal process. The morphological and structural studies of Fe3O4/rGO nanodiscs are analyzed by various techniques such as XRD, XPS, SEM, TEM, and TGA, etc. The Fe3O4/rGO electrode is tested as a negative electrode in a basic potassium hydroxide (KOH) electrolyte using a three-electrode system for supercapacitor applications. The optimized electrochemical properties of Fe3O4/rGO are systematically compared with bare Fe3O4 and it is found that the rGO greatly enhanced its performance as a negative electrode. The Fe3O4/rGO nanodiscs demonstrated a notably high-specific capacitance of 1149 F/g at 1.5 A/g better than that of Fe3O4 nanodiscs (920 F/g at 1.5 A/g). Furthermore, the Fe3O4/rGO displays the superior cyclic stability of 97.53% after running continuous 10000 GCD cycles at a high current density of 10 A/g, while bare Fe3O4 attained 87.82% at identical conditions. The fascinating electrochemical performance can be benefited for future fabrications of iron graphene-based negative electrode material for SCs.

(Invited) Intermediate Temperature Direct Ammonia Fuel Cell Using Alkaline Electrolyte System

Ammonia is a very attractive carbon-neutral fuel due to its low cost, high energy density, and existing transportation infrastructure. However, the viable commercial application of direct ammonia fuel cells (DAFC) has not been realized, largely due to materials challenges. Generally, DAFCs either use low temperature polymer electrolytes, which are limited by low reaction rates, or use high temperature solid oxide electrolytes, which suffer from severe material thermal degradation. We have developed an intermediate temperature alkaline electrolyte-based DAFC that operates at 400-600 °C, enabling high reaction rates while limiting thermal degradation. This DAFC is based on our innovative molten hydroxide electrolyte impregnated in a porous ceramic matrix, which has conductivity as high as 0.4 S/cm at 350 °C, enabling rapid hydroxide transport. The DAFCs use state-of-the-art ammonia oxidation catalysts and ammonia-tolerant ORR catalysts developed in-house and by our collaborators at SUNY Buffalo and University of Delaware. Our DAFC has demonstrated an OCV of 1.2 V and can achieve 300 mA/cm2 at 0.86 V, or >250 mW/cm2 power from pure humidified ammonia. It is stable for days without loss of activity and has very low ammonia crossover, enabling the high OCV and high power density without catalyst poisoning. Further work on catalyst development and cell design is underway to achieve higher power densities and reduce PGM catalyst loading and operation temperature, making this a more commercially viable technology.Acknowledgements: This work is financially supported by the Department of Energy’s ARPA-E under the award# DE_AR000814

(Invited) Cathodic Corrosion of Polycrystalline Au Electrodes: Applications in Electrocatalysis and Surface Spectroscopy

Faceting and nanostructuring of polycrystalline Au electrodes by cathodic corrosion in concentrated aqueous alkali metal hydroxide electrolytes have been studied systematically. Scanning electron micrographs show the formation of octahedral Au nanocrystals and triangular pits by using NaOH and KOH solutions, respectively. These Au surfaces with preferential (111)-texture and a unique nanostructure are of special interest for new developments and applications in electrocatalysis and surface-enhanced Raman spectroscopy (SERS). Cathodic corrosion of Au leads to a single-crystal-like electrochemical behavior with characteristic features of Au(111) electrodes. The electrocatalytic behavior of this new type of nanostructures will be presented for the hydrogen evolution reaction (HER) and for the formic acid oxidation reaction (FAOR). The Raman activity of adsorbed pyridine on the nanostructured Au electrodes was studied with SERS. While untreated polycrystalline Au is not SERS-active, the use of cathodic corrosion opens up a way for in-situ SERS-applications in electrochemistry. Figure 1

Carbon Nitride / Reduced Graphene Oxide Composite for Electrochemical Energy Storage Applications

A composite of carbon nitride (CN) and reduced graphene oxide1(RGO) were prepared and used as an electrode material for supercapacitor application. The limited electrical conductivity of carbon nitride is overcome by initially protonating the carbon nitride (p-CN) by refluxing, to increase its conductivity2. The p-CN was hydrothermally treated with graphene oxide to form a composite of p-CN/RGO. Morphology was analysed using a scanning electron microscope (SEM); it reveals an interlayered structure of carbon nitride and graphene. The electrochemical behaviour was studied using a three-electrode system using sulphuric acid and potassium hydroxide as an electrolyte. Electrochemical behaviour was studied using cyclic voltammetry within a potential window of -0.4 to 0.75V. The characteristics show a nearly rectangular shape showing the double layer capacitance behavior. The sulphuric acid medium was found to be better electrolyte for the composite as there were no signs of voltage drop in comparison with potassium hydroxide electrolyte. The composite electrode was found to be a better electrode for supercapacitor applications. References 1 C. Lu, Y. Yang and X. Chen, Nano Lett., 2019, 19, 4103–4111.2 Q. Li, D. Xu, J. Guo, X. Ou and F. Yan, Carbon N. Y., 2017, 124, 599–610. Figure 1

Facile synthesis of ternary nanocomposite of polypyrrole incorporated with cobalt oxide and silver nanoparticles for high performance supercapattery

Ternary nanocomposites of polypyrrole (PPy) incorporated with cobalt oxide nanograin (Co3O4), and silver (Ag) nanoparticles were synthesized by hydrothermal methodology and further utilized in supercapattery as a positive electrode material. The synthesized ternary nanocomposites (Ag/Co3O4@PPy), as well as their counterparts (Co3O4@PPy and PPy), were analyzed by various analytical techniques such as field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical characterizations such as cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy studies were performed using standard three electrodes cell system in potassium hydroxide (1 M KOH) electrolyte to evaluate the best performing electrode material. Electrochemical studies revealed that the ternary nanocomposites provided much higher specific capacity, low charge transfer and Warburg resistance compared to Co3O4@PPy and pure PPy. The best performing nanocomposite, (Ag/Co3O4@PPy) was used as a positive electrode material for the fabrication of supercapattery which delivered the highest energy density of 24.79 Wh kg−1 and a corresponding power density of 554.40 W kg−1 at a current density of 0.7 A g−1. Moreover, the supercapattery of ternary nanocomposites showed 153.67% of capacity retention even after 3000 cycles. Hence, the synthesized ternary nanocomposites have significant potential to be used in highly stable supercapattery.

Electrochemical Performance of Molybdenum Disulfide Supercapacitor Electrode in Potassium Hydroxide and Sodium Sulfate Electrolytes

Two-dimensional materials have attracted growing interest in research because of their specific electronic, physical, optical and mechanical properties. Molybdenum disulfide was theoretically investigated as novel energy storage materials because of its unusual physicochemical properties. This paper describes easy approach to fabricate molybdenum disulfide (MoS2) electrode using slurry technique on conducting substrate namely Ni foam as current collector for supercapacitor device application. This MoS2 electrode exhibits relatively good specific gravimetric capacitance, (Csp) of 11.12 to 12.38 Fg-1 at 1 mVs-1 scan rate. Moreover, galvanostatic charge-discharge displays symmetrical triangular curves which attributed to the fast charge-discharge process (in seconds). These results show that MoS2 active material can be charged and discharged reversibly between 0.2 and 1.0 V (in 6 M KOH) and between 0.3 and 1.0 V (in 0.5 M Na2SO4). From cyclic stability test exhibits capacitance retention of up to 83% and 64% after 1000 cycles in 6 M KOH and 0.5 M Na2SO4, respectively. The MoS2 electrode is thus a promising material for future application of the supercapacitor.

Feasibility study of polypropylene-based aluminium-air battery

The global economy depend on the fossil fuel to meet the daily power demands, ranging from electricity supply to transportation. It is estimated that more than 60% of the world power generation is depending on the fossil fuel. Therefore, the search for clean energy to replace fossil fuel has become the current research trend in the world. Metal-air battery featuring high energy density is projected as one of the promising candidate for the next generation energy storage system. There are various type of metal-air batteries available in the literature such as lithium-air battery, magnesium-air battery, silicon-air battery, aluminium-air battery, zinc-air battery, etc. However, aluminium-air batteries with its low cost and high energy density of 4300 Wh/kg show a great potential for future energy storage applications. In this study, the performance of the aluminium-air battery with polypropylene separator is being investigated. The battery is filled with 1M of Potassium Hydroxide electrolyte. Anode of the battery is made of Aluminium foil and carbon fibre cloth is used as cathode of the battery. The experimental results shown that, the maximum capacity of 23 mAh can be achieved using 6.25 mA of constant current discharge. By connecting the batteries in series, it is sufficient to power on a light-emitting diodes and charging a mobile phone.

Discharge performance of Zn‐air fuel cells under the influence of Carbopol 940 thickener

A dynamic research endeavor has been performed in this research study by constructing and operating an innovative flowing type anode (zinc gel) along with Carbopol 960 additives as thickener in a zinc-air fuel cell. This gel constituted of a mixture of Zn powder, thickener, and potassium hydroxide (KOH) electrolyte, and it was fueled into the cell with a peristaltic pump. The flowing Zn anode allowed the reaction-produced water, carbonate, and zinc oxide (ZnO) to be discharged from the cell. Basic operating parameters of the fuel cell like the concentrations of the Zn powder, thickener, and electrolyte along with the number and grid density of the current collector grid, cell operation temperature, and air flow rate were all optimized for effective and enhanced fuel cell performance. It was determined based on voltage production along with current and energy density generation. The augmented experimental results were as follows; thickener concentration of 1 to 2 wt% was observed to be optimum above which the electrolyte acquired a solid state. The voltage production was stable at electrolyte concentrations of 60 to 65 wt% and Zn powder concentrations lower than 40 wt%, and concentrations greater than this resulted in reduced cell performance. The implementation of four current collector grids each with an opening density of 144 grid/cm2 had efficiently amplified cell performance. The ideal cell temperature was determined to be 40°C, and maximum cell production was attained at an air flow rate of 2 m/s. Consequently, effective improvement and advancement in the processes and operational parameters were achieved in this zinc-air fuel cell with a state-of-the-art anode fuel. This will surely provide great opportunities for their applications in the future.

Photoactivity and light harvesting in ZnO nanorod arrays/Au/CuS heterostructures

Zinc oxide (ZnO) nanorod arrays (NRs)/gold (Au)/copper sulfide (CuS) heterostructures were grown by way of a low-temperature chemical approach, magnetron sputtering deposition and the successive ionic layer absorption and reaction route. The structural characteristics, morphological characteristics, elemental composition, current–voltage characteristics, ultraviolet–visible–near-infrared absorption and photocatalytic and photoelectrochemical properties of the ternary zinc oxide NR/gold/copper sulfide heterostructures were studied. The photocatalytic efficiency of the zinc oxide NRs/gold/copper sulfide heterostructures was higher than that of their zinc oxide NRs/copper sulfide counterparts. The zinc oxide NRs/gold/copper sulfide heterostructures were visible-light-photosensitive due to the lower bandgap of copper sulfide and localized surface plasmon resonance excitation of gold. The Schottky junction can motivate the photogenerated electron–hole to separate and transfer in opposite direction. The zinc oxide NRs/gold/copper sulfide heterostructures had a diode-like behavior. The electronic transition can be facilitated between ZnO NRs/gold/copper sulfide heterostructure and 1 M potassium hydroxide (KOH) electrolyte.

A Low-Cost Iron-Based Current Collector for Alkaline Battery Electrodes

The use of three-dimensional porous nickel foam as the current collector of the nickel hydroxide electrode adds significantly to the cost of the nickel-based alkaline rechargeable batteries. Although iron is considerably less expensive than nickel, iron corrodes at the operating potential of the nickel hydroxide electrode. We have found that a 70–100 nm thick thermal coating of cobalt ferrite spinel protects the iron from corrosion. Such a coated iron substrate was found to be stable against corrosion even when polarized anodically at 10 mA cm−2 in 30% potassium hydroxide electrolyte for 1000 h. While the thermal coating of cobalt ferrite protected iron against corrosion, incorporation of lithium ions into the coating was found to enhance the electrical conductivity of the coating. XPS and EXAFS studies confirmed that the enhanced conductivity resulted from an increase in the population of Co3+ in the ferrite spinel lattice. An inexpensive iron (steel) substrate protected by such a coating when used as a nickel hydroxide battery electrode exhibited a specific capacity of 0.25 Ah g−1 at C/5 discharge rate, comparable to a nickel hydroxide electrode based on a relatively expensive nickel foam substrate. The steel-based electrode also exhibited no noticeable degradation over 150 cycles at C/2 rate. This demonstration of a robust and economical steel substrate presents a unique opportunity for reducing the cost of the nickel hydroxide battery electrode in alkaline batteries.

Study of passivation treatment on SS321 electrolyte reservoir used in AgO-Zn reserve battery, for defence applications

SS321 is used as the electrolyte reservoir to store potassium hydroxide electrolyte. The metal is prone to get corroded at the electrolyte environment. The present work is carried out for minimizing the corrosion of SS321 potassium hydroxide electrolyte reservoir which is a part of the AgO-Zn reserve primary battery by passivation with citric acid. The uniqueness of the present work exhibits the optimization of passivation method and process conditions, to withstand concentrated alkaline (KOH) medium stored in SS321 electrolyte reservoir, which is having a long life of more than 7 years. Polarization and KOH resistance tests suggest that AISI 321 showed excellent passivation studies behavior when treated with citric acid solution. Hence it is necessary to establish the corrosion behavior of SS321 electrolyte storage container in alkaline solution by electrochemical studies. The thickness loss and weight loss are the main parameters measured to quantify the amount of corrosion. The Voltammetry and AFM studies established the minimum corrosion rate by passivation process method. Based on the results of electrochemical studies and anodic polarization experiments, it was confirmed that the passivation layer formed by treating the material with Citric acid, is capable of improving the corrosion resistance of stainless steel significantly and the passive film is more stable than those produced by other passivating methods. Thus, to minimize the rate of corrosion on electrolyte storage container for the period of battery life of more than 7 years, citric acid passivation having a good corrosion resistance in concentrated alkaline electrolyte (KOH) medium, is best suited and the method of treatment involved is benign & environment friendly.

Electrochemical Power Generation from Carbon in Fuel Cell with Molten Hydroxide Electrolyte

Electrochemical Power Generation from Carbon in Fuel Cell with Molten Hydroxide Electrolyte

Electrochemical polarization analysis for optimization of external operation parameters in zinc fuel cells.

Zinc–air flow fuel cells utilizing zinc particles as fuel possess the potential to evolve as efficient distributed grid generators. In this research study, electrochemical impedance analysis was employed to determine the optimum design and operational parameters for the feasible maneuver and enhanced energy generation from zinc fuel cells. Polarization resistance (Rp), ohmic resistance (Rs), and mass transfer resistance (Rm) were used as the indicators for determination of the optimum parameters of fuel cell performance. Experimental conditions optimized from previous studies like potassium hydroxide electrolyte with temperature of 25 °C and concentration of 40 wt% zinc powder quantity of 20 g, electrode reaction surface area of 48 cm2 were followed in the fuel cells used in the present study. Parameters like collector plate material, air flow velocity and cell operating temperature were augmented and finally were all implemented in the fuel cell and operated. Plain nickel or nickel-plated copper were both advantageous as collector plate materials whereas an air flow velocity ranging from 1–3 m s−1 and a cell operating temperature of 25 °C to 45 °C were beneficial for the stability and performance of the zinc fuel cells. Finally, based on the optimized parameters obtained from the above experiments, performance tests of zinc fuel cells were investigated. The maximum power produced was 16.5 W, along with a corresponding voltage of 0.8 V, maximum current density of 430 mA cm−2 and peak power density of 364.6 mW cm−2. Thus it can be concluded that the fuel cells designed and operated in this study were capable for feasible and efficient future applications.

Effect of hydroxy gas addition on performance and exhaust emissions in variable compression spark ignition engine

Due to increase in the usage of fossil fuels and the various engine emissions which are polluting the environment, it is necessary to go for an alternative method to meet the scarcity of fuels and to reduce the emissions. Expert studies indicate the use of hydroxy gas produced using water by electrolysis in petrol/diesel engine can be the solution for the integrated problem of depletion of hydrocarbon fuels and exhaust emissions. This study mainly deals with the outcome of adding hydroxy gas to gasoline on the performance of variable compression gasoline engine and engine emissions. Currently hydroxy gas is generated in a leakage proof Plexiglas generator with potassium hydroxide electrolyte and is attached to a 4-stroke water cooled variable compression gasoline engine. The results from the experimental study conducted on the engine for compression ratios ranging from 7 to 10 shows a decrease in the total fuel consumption and an increase in brake thermal efficiency due to increase in velocity flame propagation assures complete fuel combustion and permits the engine to be operated at lean ranges. Also the exhaust emissions CO2, CO, O2, HC and NOx are measured by hydroxy gas addition to gasoline and without it