查看更多>>摘要：The electrocatalytic oxygen evolution reaction (OER) is the bottleneck to overall water splitting because of the slow kinetics of the four-electron transfer process. Therefore, it is of great significance to develop OER electrocatalysts with high activity, long durability, and scalability. Herein, we present a selenium-coated cobalt selenide (CoSe2@Se) catalyst that was first synthesized by in-situ growth on carbon cloth (CC) surface by hydrothermal method, followed by soaking treatment to prepare a three-dimensional coral-like Fe2O3-CoSe2@Se/CC composite. Electrochemical studies revealed that the optimized Fe2O3-CoSe2@Se/CC catalyst only requires 250 mV to reach 10 mA cm(-2) current density, yields a small Tafel slope (50.2 mV dec(-1)), and has good stability (10 mA cm(-2)@70 h) in the electrocatalytic OER process. The overall water splitting using Fe2O3-CoSe2@Se/CC as anode only requires 1.58 and 1.69 V to achieve 10 and 100 mA cm-2, respectively, much better than most previously reported catalysts. Analysis showed that the three-dimensional coral-like morphology exposing more active sites and the synergy between different species (giving rise to, inter alia, a favorable electronic structure that lowers the electrode overpotential) are the key to the observed improved electrocatalytic performance. This work provides a novel strategy for the rational design of nanostructured OER hybrid catalysts in the future.
Whelan, Simon PeterTehrani, ZariPeacock, MartinPaulin, Joao Vitor...
5页
查看更多>>摘要：Screen printed pH sensors have been developed that utilise conductive carbon/graphene coated with DMSOmelanin for pH sensitivity. Their effectiveness has been demonstrated in buffer solutions and here they have been tested in a mixture of various frequently used culturing media solutions along side live bacteria in order to assess their suitability for monitoring the pH in real world bacterial culturing applications. The results indicate that these sensors can be used to accurately and consistently determine the pH of culturing media solutions at a high sensitivity in the presence of bacterial growth over the biologically relevant range of pH5 to pH8. This sensitivity was consistent between different types of culturing media that the sensor was tested with (brain heart infusion, nutrient and lysogeny broth) as well as pH reference buffer solutions. Therefore based on these findings it can be concluded that this sensor is sufficiently robust and has the potential to be useful in applications such as monitoring the ambient conditions of cultured microorganisms in a bioreactor.
查看更多>>摘要：Understanding the gating mechanism of ion channel proteins is the basis for regulating cell activity and design -ing new drug molecules, but it still remains a great challenge. Herein, a new tethered bilayer lipid membranes (tBLMs) model was proposed to accommodate the voltage-gated ion channel model-Alamethicin (Alm) pep-tides. Using surface-enhanced infrared absorption (SEIRA) spectroelectrochemistry combined with fluores-cence spectroscopy, it was found that the orientation of the peptides inserted into the membranes was affected by membrane dipole potential regulated by chaotropic anions. A lower dipole potential could reduce the energy barrier of the insertion of peptides into the membranes, which facilitates the peptides to adopt a more upright orientation in the membranes. This research is of great significance for understanding the mech-anism of ion channel-related diseases.
查看更多>>摘要：Capping agents are frequently used in electrodeposition to support spatially inhomogeneous mass transfer at small scales. As such, chloride ions are known to support the deposition of conically nanostructured nickel layers. This work presents a systematic experimental study of the impact of a capping agent on the electrochemical growth of conically-shaped nickel deposits. Furthermore, a modeling approach on the scale of cones for numerical simulations of electrodeposition with capping agents is provided for the first time to give deeper insight on how the capping agent influences the local growth of the deposit. The growth rates of the nano-cones obtained numerically are compared with experimental data, and a good agreement is found. The impact of the capping agent concentration, the deposition time, the electrolyte temperature and the current density are investigated systematically, and optimum conditions for conical growth are derived.
查看更多>>摘要：Quartz Crystal Microbalance (QCM) is a scientific instrument hinged on the piezoelectric effect of quartz crystals. Due to its versatile, reliable, and sensitive in-situ sensing ability for small quantity variations, QCM and Electrochemical-QCM (EQCM) techniques have already been applied to precise analysis and control of crystallization and electrodeposition process. The sudden shift from viscous friction to elastic friction during liquid/solid phase transition can be accurately reflected by a resonant frequency shift. Therefore, the complex frequency change measured by QCM or EQCM contains implicit information about the processes of crystallization and electrodeposition. In this review, QCM analysis methods during crystallizing or electrodepositing of different objects are classified and reviewed. The key factors including intermolecular forces, substrate geometries, additives, and types of solutions are discussed. The future applications of QCM in crystallization and electrodeposition were outlooked.
查看更多>>摘要：Airbreathing microfluidic fuel cell (MFC) is emerging as the potential energy source for prospective use in glucose sensors, pacemakers, healthcare diagnostics, mobile phones, and DNA analysis devices, etc. A mathematical model of airbreathing MFC can aid in the explanation of a system as well as the prediction of behavior. In this line of work, the mathematical model for an airbreathing MFC was developed. Moreover, various losses such as activation, ohmic, and concentration overpotentials at anode and cathode were taking into account in the development of mathematical model. This developed model was validated with experimental data on current density vs. cell voltage characteristics at different fuel concentrations of 0.25 M to 1 M (CH3OH, C2H5OH) and 0.05 M to 0.3 M (NaBH4) along with cell temperatures (33 degrees C, 50 degrees C and 65 degrees C). For these experiments, the electrocatalysts used to prepare the anodes were Platinum-Ruthenium (Pt-Ru) (30%:15% by wt.)/ high surface area carbon (CHSA) (fuel: CH3OH, C2H5OH), and Platinum (40% by wt.)/CHSA (fuel: NaBH4). The cathodes were prepared using Pt (40% by wt.)/CHSA. The model's findings are in agreement with the experimental results well. Model prediction equation fairly reflected the influence of process variables such as fuel/electrolyte concentration and cell temperature on the prediction. The standard deviation values are found very low (0.02 to 0.082), indicating that developed mathematical model can be utilized in development of devices for industrial along with lab based applications. A high standard deviation, on the other hand, implies that the values are spread out across a higher range.
查看更多>>摘要：In this work, graphene with SiC3 ligand is proposed as a high-performance nitrogen reduction reaction (NRR) electrocatalyst using density functional theory simulations. The Si atom holds a high positive charge which enable it to accommodate the lone pair electrons on N2, resulting in the capture of N2. More importantly, the electrocatalyst presents the minimum change of Gibbs free energy (0.19 eV) at the potential determining step (*N-N ->*N-NH) and the minimum overpotentials (0.03 V) among reported metal-free electrocatalysts. The introduction of SiC3 ligand does not impair the conductivity of graphene. Additionally, the electrocatalyst is stable at 298 K and solvation environment using the ab initio molecular dynamics (AIMD) calculation. This study provides a new guided strategy for developing and preparing carbonous materials to enhance the NRR performance experimentally.
查看更多>>摘要：Voltammetry is a foundational electrochemical technique that can qualitatively and quantitatively probe electroactive species in solutions and as such has been used in numerous fields of study. Recently, automation has been introduced to extend the capabilities of voltammetric analysis through approaches such as Bayesian parameter estimation and compound identification. However, opportunities exist to enable more versatile methods across a wider range of solution compositions and experimental conditions. Here, we present a protocol that uses experimental voltammetry, physics-driven models, binary hypothesis testing, and Bayesian inference to enable robust labeling of analytes in multicomponent solutions across multiple techniques. We first describe the development of this protocol, and we subsequently validate the methodology in a case study involving five N-functionalized phenothiazine derivatives. In this analysis, the protocol correctly labels solutions each containing 10H-phenothiazine and 10-methylphenothiazine from both cyclic voltammograms and cyclic square wave voltammograms, demonstrating the ability to identify redox-active constituents of a multicomponent solution. Finally, we identify areas of further improvement-such as achieving greater detection accuracy-and future applications to potentially enhance in situ or operando diagnostic workflows.
查看更多>>摘要：We report here on the use of regenerated cellulose-based dialysis membranes as liquid junction materials to be used in electrochemical reference electrodes targeted towards environmental analysis. With high bridge electrolyte concentrations (above 100 mM), the response fitted the predictions based on the Henderson equation but an undesirable net flux of ions escaping the membrane (For 1 M KCl: J = 14.2 +/- 0.8 mmol center dot m-2 center dot s-1) was observed. The use of less concentrated bridge electrolyte (10 mM) resulted in deviations of up to 26 mV between experimental data and theoretical predictions. Due to the failure to estimate the liquid junction potential arising at the interface with the classical Henderson equation, a simple calculation method, providing a better fit towards experimental data, was developed and tested. The proposed model is based on partial Donnan exclusion generated by the charged surface of the membrane in aqueous samples. The validation of the new model was achieved through a comparison with the Nernst-Poisson-Planck (NPP) simulation method normally used to calculate the potential across permselective membranes. This setup was tested with water samples from the Arve river, where the bridge concentration was closely matched to the sample. Deviations between the new model and experimental data stayed below 0.5 mV, while they were above 6 mV for the Henderson equation. Because of the simple mathematical treatment, the new model may be used to estimate the charge density of such membranes.
查看更多>>摘要：This work focuses on the production of electricity using chloralkaline high temperature PEM fuel cells (HTPEMFC) comparing, within the range 120-180 degrees C, the performance of a cell equipped with a cathode containing a novel Ru/Pt catalyst manufactured at mild temperature conditions with another cell which contains a conventional Ru based catalyst (Ru0.75Pt0.25O2). Performance of the cell equipped with the conventional electrode at 120 degrees C is much better, but this situation reverses at higher operation temperatures, where the novel catalyst outperforms the conventional Ru0.75Pt0.25O2 in terms of production of electricity. In addition, the new catalyst allows to operate even at 180 degrees C, temperature at which the cell equipped with the conventional electrode is completely deteriorated. Results pointed out that materials are the bottleneck for the chloralkaline HT-PEMFC technology but opens the window for the search of new materials that help to improve their future development.
NSTL
Elsevier