Inorganic mineral doped polypyrrole for hydrogen storage in alkaline medium

Cupric chloride is used as oxidant to synthesize polypyrrole doped with inorganic mineral (ImDPpy). The formation of ImDPpy was confirmed by ¹HNMR, BET, SEM, HRTEM, DSC, FTIR, Raman, XRD, UV–vis and XPS studies. The surface area calculated for ImDPpy is 36.671 m²/g. Surface area of IMDPpy is 4.671 m²/g higher than the reported value of Ppy in the literature. In DSC, ImDPpy display a peak at 88.07 °C (endothermic glass transition temperature, Tg), Tg of ImDPpy is almost identical to that of Ppy-MWCNT composite and is higher than Tg of undoped Ppy. Electrochemical analysis of ImDPpy in 0.01 M NaOH indicated the maximum charge stored in ImDPpy in the form of protons as 8090 mF/g. The maximum hydrogen storage capacity of ImDPpy is found to be 18mAh/g at an applied current density of 1 mA/cm². The mineral doped in Ppy during polymerization is identified as [Cu₂(OH)₃Cl] from XPS and Raman analysis.     

High-resolution FIB-TEM-STEM structural characterization of grain boundaries in the high dielectric constant perovskite CaCu3Ti4O12

In this work, the grain boundaries composition of the polycrystalline CaCu₃Ti₄O₁₂ (CCTO) was investigated. A Focused Ion Beam (FIB)/lift-out technique was used to prepare site-specific thin samples of the grain boundaries interface of CCTO ceramics. Scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray spectrometry (EDXS) and Electron Energy Loss Spectroscopy (EELS) systems were used to characterize the composition and nanostructure of the grain and grain boundaries region. It is known that during conventional sintering, discontinuous grain growth occurs and a Cu-rich phase appears at grain boundaries. This Cu-rich phase may affect the final dielectric properties of CCTO but its structure and chemical composition remained unknown. For the first time, this high-resolution FIB-TEM-STEM study of CCTO interfacial region highlights the composition of the phases segregated at grain boundaries namely CuO, Cu₂O and the metastable phase Cu₃TiO_4.     

When less is more – Effects of providing simple vs. refined action-knowledge interventions to promote climate-friendly food consumption in German consumers

A crucial challenge in global climate protection involves figuring out how to promote climate-friendly (CF) food consumption in high-income countries. Improving consumers’ ability to identify CF food is a promising way to reach this goal. Previous research has shown that providing action-knowledge is an intervention technique that can effectively improve the mentioned ability if relevant preconditions are considered. The present study (further) examined such preconditions and possible refinements of this intervention technique in a representative sample of German consumers (N = 510). Participants were randomly assigned to one of two experimental groups (EG1 received simple guidelines for CF food consumption; EG2 received refined guidelines for CF food consumption) or a control group (CG) without any intervention. Altogether, the present study clearly demonstrates that simple guideline-provision is a promising and easy-to-use tool for interventions aimed at improving consumers’ ability to identify CF food in daily life.     

Multi-period wind integrated optimal dispatch using series PSO-DE with time-varying Gaussian membership function based fuzzy selection

Wind power has emerged as the most promising option for providing sustainable eco-friendly power supply to the modern world. Due to its unpredictable nature, integration of wind power into the conventional power grid is a very challenging task having dynamic characteristics. Due to the inherent uncertainty associated with wind availability, additional spinning reserve needs to be scheduled in order to maintain security and supply reliability. Multi-period multi-objective optimal dispatch (MPMOOD) is presented for wind integrated power system with reserve constraints. The complex relationship between wind power availability, spinning reserve allocation and their impact on economic/environmental cost are analysed using an elaborate model.A new multi-objective Series PSO-DE (SPSO-DE) hybrid algorithm is proposed where the two paradigms, differential evolution (DE) and particle swarm optimization (PSO) share domain information and maintain a synergistic cooperation to overcome their individual weaknesses. For multi-objective (MO) problems, the selection operation in SPSO-DE is replaced by a 5-class time-varying fuzzy selection mechanism (TVFSM) to avoid saturation and to increase Pareto diversity. To promote convergence towards the central part of the Pareto front and to quickly isolate the boundary solutions, Guassian membership function is employed. Elitism is applied to preserve good solutions and momentum operation is used to stop premature convergence. The proposed method expedites the search for the best solution, i.e. the solution which satisfies all the objectives of the MO problems. To test the performance and computational efficiency, the proposed method is applied on two standard test power systems.     

Experimental studies on the effects of sheet resistance and wettability of catalyst layer on electro-catalytic activities for oxygen evolution reaction in proton exchange membrane electrolysis cells

As the most important part of electrochemical reaction in proton exchange membrane electrolysis cells (PEMECs) for water splitting, oxygen evolution reaction (OER) occurs at the anode catalyst layer (CL). The distribution of the OER site is affected by many factors, such as properties of CL, operation parameters, procedures, etc. To study the effects of properties of CLs on the distribution of OER site on the CL, and consequently affect the performance of PEMECs, CLs with different sheet resistances are tested under different operation conditions. The phenomena of OER on CLs are captured by a high-speed and micro-scale visualization system in-situ and analysed coupled with electrochemical results. The results show that both sheet resistance and wettability of CLs have significant impact on the distribution of the OER site, which can help optimize the design of membrane electrode assembly and improve the operating parameters for electrochemical devices.     

Effect of Eu3+-doping on morphology and fluorescent properties of neodymium vanadate nanorod-arrays

Tetragonal structural (t-NdVO₄) nanorod-arrays were fabricated by simple one-pot hydrothermal method. The phase, morphology and microstructure of NdVO₄ were characterized by X-ray diffractometer, scanning electron microscope (SEM), transmission electron microscope (TEM), dispersive X-ray spectrometer (EDS) and selected area electron diffraction (SAED) techniques. t-NdVO₄ nanorods are single-crystalline with a length of 100 nm and a diameter of 25 nm, which grow orientally along the direction of (112) crystalline plane and self-assemble to form nanorod-arrays. The results show that Eu³⁺-doping interrupts the formation of NdVO₄ nanorod-arrays, and then leads to the red-shift of the strongest luminescence emission of Nd³⁺ transition from ⁴D_3/2 state to ⁴I_11/2 and decreases its intensity of the fluorescence emission at 400 nm sharply. The research results have some reference values to optimize the photoluminescence performance of rare earth vanadates.     

Enhanced electrochemical performance of supercapattery derived from sulphur-reduced graphene oxide/cobalt oxide composite and activated carbon from peanut shells

Sulphur-reduced graphene oxide/cobalt oxide composites (RGO-S/Co₃O₄) were successfully synthesized by varying mass loading of Co₃O₄ through a simple hydrothermal method. Structural, morphological, chemical compositional and surface area/pore-size distribution analysis of the materials were obtained by using XRD, Raman spectroscopy, SEM, TEM, EDX, FTIR, XPS and BET techniques, which reveal an effective synthesis of the RGO-S/Co₃O₄ composites. Electrochemical performance of the materials was evaluated using a three- and two-electrode system in 1 M KOH electrolyte. An optimized RGO-S/200 mg Co₃O₄ composite displayed the highest specific capacity of 171.8 mA h g⁻¹ and superior cycling stability of 99.7% for over 5000 cycles at 1 and 5 A g⁻¹, respectively, in a three-electrode system. A fabricated supercapattery device utilizing RGO-S/200 mg Co₃O₄ (positive electrode) and activated carbon from peanut shells (AC-PS) (negative electrode), revealed a high specific energy and power of 45.8 W h kg⁻¹ and 725 W kg⁻¹, respectively, at 1 A g⁻¹. The device retained 83.4% of its initial capacitance for over 10, 000 cycles with a columbic efficiency of 99.5%. Also, a capacitance retention of 71.6% was preserved after being subjected to a voltage holding test of over 150 h at its maximum potential of 1.45 V.