Two-step Reduction Process Research Articles

Electrochemical extraction kinetics of Nd on reactive electrodes

• Pyroprocessing technology is a promising technology for the reprocessing of spent fuel. • It is critical to pursue electrode materials with high An / Ln separation efficiency. • The electrochemical reduction of Nd 3+ on the W electrode is a two-step reduction process. • The kinetic properties of Nd 3+ on W, reactive electrodes were measured. • Cd was evaluated as a favorable electrode material for electrochemical extract ion of Nd. Pyroprocessing technology with molten salt electrolysis as the core is a promising technology for the reprocessing of spent fuel. In this work, the electrochemical reduction mechanism and kinetic properties of Nd 3+ on various electrodes (inert W and reactive Al, Ga, Bi, Cd, Zn, Pb, and Sn electrodes) were systematically investigated and compared in LiCl-KCl eutectic melts using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel techniques. The electrochemical reduction of Nd 3+ was a two-step process on the W electrode including Nd 3+ →Nd 2+ and Nd 2+ →Nd, while it became a one-step process involving three electrons on the reactive electrodes with obvious depolarization effects. Furthermore, the connections between the reduction potentials of Nd 3+ on these reactive cathodes and the formation energies of the electrode-rich alloy phases (Al 11 Nd 3 , Cd 11 Nd, Pb 3 Nd, Zn 17 Nd 2 , Ga 6 Nd, Sn 3 Nd, BiNd 2 ) were established. After evaluating the physicochemical, depolarization and kinetic properties of these reactive electrodes, liquid Cd was considered as the most favorable material for the electrochemical extraction of Nd. In addition, Al, Cd, and Bi are also promising candidates for An / Ln separation.

Nitro group as a redox switch in urea-based receptors of anions

• NO 2 group was used as an electrochemical binding/release switch in anion receptors. • Binding enhancement factor of the receptor is dependent on NO 2 position. • Reduction processes were elucidated by electrochemical/spectroelectrochemical methods. • Complexation of dihydrogen phosphate changes the receptor reduction mechanism. A nitro group was used as an electrochemical binding/release switch in urea-based receptors for anions. The oxidized and reduced forms of the receptors were thoroughly studied, evaluating the impact of structural features on the binding affinity upon redox modification. In the case of a nitro group in the p- position to the urea moiety, the association constant of the oxidized form is up to 80 times higher than the value measured for the reduced form. The possible application of such an anion binding affinity switch was tested electrochemically in reduction of the nitro group up to the hydroxylamine stage. The presence of acidic urea protons induces a three-step auto-protonation mechanism, however, the complexation of dihydrogen phosphate prevents the urea proton dissociation, which leads to a standard two-step reduction process. Taking advantage of redox-sensitive NO 2 chromophore, the whole process was also monitored using spectroelectrochemical measurements.

Identification of the molecular pathways of RuO2 electroreduction by in-situ electrochemical surface-enhanced Raman spectroscopy

RuO2 is one of the most promising catalysts for oxygen evolution reaction (OER), a key reaction in water electrolysis. However, the fundamental insights about the structural evolution of RuO2 under different electrochemical environments remain unclear. Herein, the molecular reaction pathways of the electroreduction of RuOx in alkaline and neutral conditions are identified using in-situ electrochemical surface-enhanced Raman spectroscopy. Au@RuO2 core–shell nanostructures are fabricated to amplify the Raman signals of species adsorbed on RuOx surfaces. Using such core–shell nanostructures, direct spectroscopic evidences of OH intermediate during the RuO2 electroreduction process are obtained, which is further confirmed by D2O isotopic substitution experiments. A molecular pathway that RuO2 is reduced to Ru through a two-step reduction process has been proposed. This work provides insightful information on the structural evolution of RuOx with electrochemical environments.

Synthesis of First Antimony Porphycene and Electrocatalytic Hydrogen Evolution Driven by Ligand-Centered Reduction

Abstract For post-transition metal electrocatalytic hydrogen evolution reaction (HER), the new porphycene antimony complexes, Sb(III)OEPo and Sb(V)OEPo-Br2, were synthesized and characterized. Based on the electrochemical and electro-spectro measurements, the two-step one-electron reduction processes of Sb(III)OEPo were indicated to be both ligand-centered and the irreversible reduction process observed for Sb(V)OEPo-Br2 was assigned to be the reduction from Sb(V)OEPo-Br2 to Sb(III)OEPo. Electrocatalytic HER proceeded at −1.0 V (vs. Ag/AgCl) under acidic conditions via the ligand-centered reductions. The electron accepting nature of the porphycene ligand enabled the utilization of a main-group element as a central element for the ligand-centered HER at anodically shifted potentials.

Ultralight, compressible, and high-temperature-resistant dual-phase SiC/Si3N4 felt for efficient electromagnetic wave attenuation

The ingenious multicomponent microstructure design provides a suitable strategy for gaining high-performance multi-functional integrated materials. Herein, the thermally stable SiC/Si3N4 composite ceramic felt was successfully fabricated via two-step carbothermal reduction processes for advanced electromagnetic (EM) wave absorption properties with strong absorption and a broad effective absorption bandwidth. X-ray absorption near-edge structure (XANES) at the C K-edge and N K-edge of as-prepared samples were investigated to understand the conversion process and electronic structures. The abundant heterogeneous interfaces and complex morphology improved the superior absorption performance by forming excellent impedance matching, multiple interfacial polarization and dipolar polarization generated from the synergistic interaction of SiC and Si3N4 dual-phase felt. The prepared SiC/Si3N4 composite ceramic felt exhibited high absorption efficiency with a minimal reflection loss of –50 dB (exceeding 99.99% wave absorption) and wide absorption band (covering 7 GHz) with a thin thickness of 2.1 mm. Furthermore, the excellent structural robustness and resilient compressibility inherited from C felt, as well as the thermostability until 950 °C under O2 guarantee the stable and durable application of the SiC/Si3N4 composite ceramic felt to resist EM absorbers, especially for in extreme high-temperature environments.

Interfacial Co-N bond bridged CoB/g-C3N4 Schottky junction with modulated charge transfer dynamics for highly efficient photocatalytic Staphylococcus aureus inactivation

• CoB/CNs Schottky junction with interfacial Co-N bond was prepared; • CoB/CNs presents excellent performance for photocatalytic S. aureus inactivation; • Interfacial Co-N bond can efficiently modulate the charge transfer dynamics; • Two-step single-electron induced O 2 reduction (O 2 → ·O 2 – → H 2 O 2 ) is enhanced. Interfacial engineering plays a critical role in modulating the electron transfer dynamics of photocatalysis, but has been rarely explored. Herein, a novel cobalt boride/graphitic carbon nitride nanosheet (CoB/CNs) Schottky junction with interfacial Co-N bond was successfully prepared to uncover the function of interfacial chemical bond in photocatalytic antibacterial process. Density functional theory (DFT) calculation and experimental investigation demonstrate that the interfacial Co-N bond can act as an electron transfer channel to efficiently steer the electron transfer from CNs to CoB, and then an upward band bending with the height of 0.26 eV is formed in CoB/CNs Schottky junction. The formed upward band bending can rapidly separate the photogenerated electron-hole pairs by preventing electrons from flowing back to the CNs, which causes the surface electron transfer efficiency ( η trans ) to increases from 41.8% (CNs) to 57.7% (CoB/CNs-2). Rotating disk electrode (RDE) results demonstrate that compared with CNs (n = 2.38), the oxygen reduction reaction in CoB/CNs-2 (n = 2.19) is more selective to a two-electron transfer route. Meanwhile, further research on reactive oxygen species reveals that it is an indirect two-step single-electron oxygen reduction process, which is beneficial for the generation of ·O 2 – and H 2 O 2 . As a result, 7 × 10 7 CFU/mL of Staphylococcus aureus ( S. aureus ) can be completely inactivated by CoB/CNs-2 with 125 min under visible light irradiation. It is expected that our work will provide some guidance for the exploitation of more advanced hybrid photocatalysts system through interfacial engineering.

Initial nucleation process in the synthesis of Platinum Nanoparticle from chloroplatinic acid

The size, morphology, and polymorphism of nano-materials, the key factors determining their physicochemical properties, are significantly affected by the nucleation processes from precursors. Understanding the nucleation kinetics at the atomic scale is fundamental to the designed synthesis of nano-materials with tailored composition, shape and size. Here we report our investigation on the nucleation process in synthesis Platinum nano-particles by chemical reduction of chloroplatinic acid in methanol and methanol/water mixed system. In synergy with the liquid chromatography mass spectrometry (LCMS) and first-principle transition-state calculations, specific reaction processes at the pre-nucleation stage are revealed in which the precursor chloroplatinic acid (H2PtCl6) undergoes a two-step reduction process to form divalent and non-valent Pt-contained clusters, respectively. It is found that in both steps, the presence of water molecular can lower the activation energy and accelerate the reaction rate through a proton transport mechanism. Moreover, through free energy analysis and ab-initio molecular dynamic simulation, we identified the initial nucleation process which is characterized by the formation of Pt-Pt bond between two divalent Pt (II)-contained clusters. The theoretical calculations explain the pre-nucleation reaction paths and the nucleation process, consistent with the LCMS measurements and previous XAFS results. This work indicates the nucleation processes in chloroplatinic acid/methanol/water system exhibit more complexities than that described by the classical nucleation theory as well as previous research results on the same system. The finding may shed light upon the size-and-shape-controlled synthesis of noble metal nanoparticles.

Electrochemical behavior and electrodeposition of gallium in 1,2-dimethoxyethane-based electrolytes.

The electrochemical behavior and electrodeposition of gallium was studied in a non-aqueous electrolyte comprising of gallium(iii) chloride and 1,2-dimethoxyethane (DME). Electrochemical quartz crystal microbalance (EQCM) and rotating ring disk electrode (RRDE) measurements indicate that reduction of gallium(iii) is a two-step process: first from gallium(iii) to gallium(i), and then from gallium(i) to gallium(0). The morphology and elemental composition of the electrodeposited layer were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Metallic gallium was deposited as spheres with diameters of several hundred nanometers that were stacked on top of each other. X-ray photoelectron spectroscopy (XPS) revealed that each gallium sphere was covered by a thin gallium oxide shell. Electrochemical experiments indicated that these oxide layers are electrically conductive, as gallium can be electrodeposited and partially stripped on or from the layer of spheres below. This was further evidenced by simultaneous electrodeposition of gallium and indium, using indium as a tracer. Electrodeposition of gallium from an O2-containing electrolyte resulted in spheres with smaller diameters. This was due to the formation thicker oxide shells, through which diffusion of gallium atoms that were electrodeposited on the surface, was slower. The concentration of gallium adatoms on top of the gallium spheres to form a new sphere therefore reaches the critical concentration for nucleating a new gallium sphere sooner, leading to smaller spheres.

Safe and Flexible Chitosan Gel Electrolyte Based Zn-MnO2 Alkaline Batteries

This work examines the use of naturally occurring chitosan with additives in a gel electrolyte and its efficient incorporation in safe, cost-effective, and rechargeable Zinc-EMD batteries. This study demonstrates (1) an energy and time efficient, scalable stage-wise preparation technique for achieving highly conducting (457mS/cm), flexible, electrochemically & thermally stable chitosan polymer electrolyte with PVA and KOH additives, along with their morphological and structural studies. This work also demonstrates (2) a robust and unique assembly technique employed to achieve good electrode/electrolyte interfacial contact when constructing a complete battery with the devised electrolyte to test its performance. (3) Employing a selective, limited potential window during galvanostatic charge-discharge tests; this work also achieved high specific capacity (310mAh/g) with good reversibility (170cycles) for Zn-EMD alkaline batteries using no cathode additives. The selective potential window approach helped utilize the available high capacity of EMD (γ-MnO2) through the two-step reduction process in addition to hindering the irreversible δ-MnO2 formations which usually hampers rechargeability in Zn-EMD alkaline batteries. The overall performance (70% capacity retention w.r.t initial, 97% and 110Wh/kg avg. energy density w.r.t cathode mass) recorded for the constructed battery with the devised gel electrolyte is comparable to the reported performances of Zn-EMD batteries with gel/liquid alkaline polymers in the literature. Culminating the electrochemical studies done on the assembled cell, it is possible to claim the successful rechargeability of our secondary batteries, which utilize novel alternative gel electrolyte fabrication methods that accommodate reversible zinc-reactions and novel cell assembly techniques.

Selective reduction of nitrate into nitrogen at neutral pH range by iron/copper bimetal coupled with formate/ferric ion and ultraviolet radiation

Nitrate reduction by zero valent iron (Fe0) has been gained increasing attention. However, two key issues, that is, the reduction is efficient only at acidic condition; and the major reduction product is ammonium, which limited the application of Fe0 for the nitrate removal. In this study, to address these issues, a novel system of Fe0@Cu0 bimetal with formate/Fe3+ under UV irradiation was developed for the nitrate reduction. The results showed that 100% nitrate removal efficiency and 98% N2 selectivity were achieved at initial pH of 6.47 by a two-step reduction process: (1) the nitrate was firstly reduced to nitrite, while ammonium was negligible in the Fe0@Cu0/formate/UV system; (2) the accumulated nitrite in the effluent from the first-step reduction could be further reduced to nitrogen by CO2•− radical generated by the reaction of formic acid, Fe3+ and UV radiation. Almost no formate residual was found in the effluent due to the action of photo-induced electron transfer of Fe3+. The optimization of operation conditions and the combination mode of Fe0@Cu0 with formate/formic acid, Fe3+ and UV were investigated. The chemical denitrification mechanism of the Fe0@Cu0 particles was proposed.

MRI Radiomics for the Prediction of Fuhrman Grade in Clear Cell Renal Cell Carcinoma: a Machine Learning Exploratory Study.

The Fuhrman nuclear grade is a recognized prognostic factor for patients with clear cell renal cell carcinoma (CCRCC) and its pre-treatment evaluation significantly affects decision-making in terms of management. In this study, we aimed to assess the feasibility of a combined approach of radiomics and machine learning based on MR images for a non-invasive prediction of Fuhrman grade, specifically differentiation of high- from low-grade tumor and grade assessment. Images acquired on a 3-Tesla scanner (T2-weighted and post-contrast) from 32 patients (20 with low-grade and 12 with high-grade tumor) were annotated to generate volumes of interest enclosing CCRCC lesions. After image resampling, normalization, and filtering, 2438 features were extracted. A two-step feature reduction process was used to between 1 and 7 features depending on the algorithm employed. A J48 decision tree alone and in combination with ensemble learning methods were used. In the differentiation between high- and low-grade tumors, all the ensemble methods achieved an accuracy greater than 90%. On the other end, the best results in terms of accuracy (84.4%) in the assessment of tumor grade were achieved by the random forest. These evidences support the hypothesis that a combined radiomic and machine learning approach based on MR images could represent a feasible tool for the prediction of Fuhrman grade in patients affected by CCRCC.

Theoretical Efficiency Limits of Photoelectrochemical CO2 Reduction: A Route-Dependent Thermodynamic Analysis.

Solar-fuel formation via photoelectrochemical (PEC) routes using water and CO2 as feedstock has attracted much attention. Most PEC CO2 reduction studies have been focused on the development of novel photoactive materials; however, there is still a lack of understanding of the key limiting factors of this process. In this study, the theoretical limits of Solar-to-Fuel (STF) efficiencies of single- and dual-junction photo-absorbing materials are illustrated for single-step multi-electron CO2 reduction into fuels including HCOO- , CO, CH3 OH and C2 H5 OH. It is also highlighted that STF efficiency depends on the route of two-step PEC CO2 reduction process using CH3 OH as a model fuel. Finally, it is illustrated the beneficial role of alternative strategies such as dual-junction photo-absorbing electrodes, externally applied bias and subsequent reactor chambers on the maximum theoretical efficiencies of PEC CO2 reduction.

Preparation of copper–silver alloy with different morphologies by a electrodeposition method in 1-butyl-3-methylimidazolium chloride ionic liquid

Electrodeposition of a copper–silver alloy based on a 1-butyl-3-methylimidazolium chloride (BMIC) ionic liquid was studied. The electrochemical behaviour of copper and silver ions was characterized by cyclic voltammogram. The morphologies and phase compositions of copper–silver alloy coating under different electrodeposition conditions were investigated by scanning electron microscopy and X-ray diffraction. The results show that copper–silver alloys with different micro-morphologies can be obtained under different potential conditions in BMIC. Co-deposition of the copper–silver alloy followed a two-step reduction process, the first step is the reduction of the cupric ion to the cuprous ion and the second step is the simultaneous reduction of the cuprous ion and the silver ion to form an alloy. A dendritic alloy can be obtained at − 0.60 V, a bract alloy can be obtained at − 0.80 V and a granular alloy can be obtained at − 1 V. The coating particle size at \(60^{\circ }\hbox {C}\) was smaller than the particle size obtained at \(40^\circ \hbox {C}\). The Cu–Ag alloy prepared by electrodeposition in ionic liquids consists of single-phase copper and single-phase silver.

Linear Mixed Effects Modelling of Oxygen Desaturation after Sleep Apneas and Hypopneas: A Pilot Study.

Obstructive Sleep Apnea severity is commonly determined after a sleep polysomnographic study by the Apnea-Hypopnea Index (AHI). This index does not contain information about the duration of events, and weights apneas and hypopneas alike. Significant differences in disease severity have been reported in patients with the same AHI. The aim of this work was to study the effect of obstructive event type and duration on the subsequent oxygen desaturation (SaO2) by mixed-effects models. These models allow continuous and categorical independent variables and can model within-subject variability through random effects. The desaturation depth dSaO2, desaturation duration dtSaO2 and desaturation area dSaO2A were analyzed in the 2022 apneas and hypopneas of eight severe patients. A mixed-effects model was defined to account for the influence of event duration (AD), event type, and their interaction on SaO2 parameters. A two-step backward model reduction process was applied for random and fixed effects optimization. The optimum model obtained for dtSaO2 suggests an almost subject-independent proportion increase with AD, which did not significantly change in apneas as compared to hypopneas. The optimum model for dSaO2 reveals a significantly higher increase as a function of AD in apneas than hypopneas. Dependence of on event type and duration was different in every subject, and a subject-specific model could be obtained. The optimum model for SaO2A combines the effects of the other two. In conclusion, the proposed mixed-effects models for SaO2 parameters allow to study the effect of respiratory event duration and type, and to include repeated events within each subject. This simple model can be easily extended to include the contribution of other important factors such as patient severity, sleep stage, sleeping position, or the presence of arousals.

Cu isotope fractionation during reduction processes in aqueous systems: evidences from electrochemical deposition

Redox processes are ubiquitous in Earth science, and redox transitions often lead to large fractionations of the stable isotopes of many transition metals such as copper. To get insights into the mechanisms of isotope fractionations induced by electrochemical processes, we examine the behavior of copper isotopes during the reduction reaction Cu2+ + 2e− = Cu0. All experiments have been conducted by applying a controlled current between the working electrode and the auxiliary electrode, i.e., the galvanostatic electrodeposition technique, in aqueous CuSO4 solutions. Controlling parameters were tested by varying electrolyte concentration (0.01–1 mol kg−1), stirring speed (0–500 rpm), current (0.1–0.5 A), time (35–600 s), and temperature (5–80 °C). In all cases, the plated Cu metal is enriched in the light isotope (63Cu) with respect to the solution. At room temperature, the Cu isotopic fractionation between the electroplated Cu and electrolyte is found to increase with electrolyte concentration and stirring speed, and to decrease with current and run duration. These trends can be interpreted by three competing processes: copper transport in the solution, kinetics of electrochemical reduction of copper ions and surface diffusion at the electrode, i.e., transport becomes important at low copper concentration, low stirring speed, high currents and large amount of copper precipitation. Copper isotope fractionation has a maximum near 35 °C, decreasing both towards higher and lower temperatures. In the temperature range of 35–80 °C, the dependence of temperature on isotope fractionation can be described by $$ \Delta^{65} {\text{Cu}}_{{{\text{Cu}}\left( 0 \right) - {\text{Cu}}({\text{II}}){\text{aq}}}} = - \left( {0.27 \pm 0.04} \right) \times 10^{6} T^{ - 2} + \left( {0.16 \pm 0.34} \right), $$ where ∆65CuCu(0)–Cu(II)aq (‰) represents the copper isotopic composition differences between the product (electroplated copper) and the reactant (electrolyte solution, CuSO4(aq)), and T is the temperature in K. At low temperature (down to 5 °C), a noticeable deviation from this trend suggests a change in the controlling mechanism, i.e., transport in the solution becomes important. Our findings are best explained by a two-step reduction process including reduction from Cu(II) to Cu(I) and a subsequent reduction of Cu(I) to Cu(0). The good agreement of our high-temperature data with the results from Ehrlich et al. (2004), who used a different experimental approach to precipitate Cu(I) mineral from CuSO4 solution, implies that transformation of Cu(II) to Cu(I) dominates the isotope fractionation observed during electrochemical reduction of Cu(II) to Cu(0). These findings support that copper isotopes can be used as effective tracers of redox processes. They may have implications to processes in hydrothermal systems and the formation of ore deposits, e.g., volcanic-hosted massive sulfides, as well as to processes in near surface aquatic environment and related supergene processes.

Selective Reduction of Nitrate into Nitrogen Using Cu/Fe Bimetal Combined with Sodium Sulfite

A novel two-step reduction process was constructed to removal nitrate selectively in aqueous solution. Nitrate was preliminarily reduced into nitrite with low yield of ammonia by microscale Cu/Fe b...

A new route for preparing Mo-10wt.%Cu composite compacts

In this work, high pure Mo-10 wt% Cu composite powders with a ultrafine particle size are prepared by a two-step reduction process (first carbothermal reduction and then hydrogen reduction). Ammonium heptamolybdate and copper nitrate trihydrate powders are used as molybdenum and copper source, respectively. The mixtures of raw materials are calcined at 400 °C firstly to form the composite oxides which are then reacted with insufficient carbon black at 1050 °C for 2 h. The as-prepared powders are further reduced by hydrogen at 750 °C for 2 h to obtain the ultrafine Mo-10 wt% Cu composite powders. The experimental results show that the residual carbon of the Mo-10 wt% Cu powders can be decreased to 0.015 wt%, and the composite powders have an average particle size of 200 nm. The sintering behavior of ultrafine MoCu powders and the properties (vickers hardness and thermal conductivity) of samples after sintering are investigated. High sintering temperature is beneficial to increase the density of the compact. At 1200 °C, the relative density of the MoCu compacts is 98.8%. The vickers hardness and thermal conductivity of the Mo-10 wt% Cu composites sintered at 1200 °C for 3 h are 233 HV and 130 (W/m·k), respectively.

A top-down chemical approach to tuning the morphology and plasmon resonance of spiky nanostars for enriched SERS-based chemical sensing

Gold-silver (AuAg) alloys, an important noble bimetallic system, have received significant attention due to their chemical stability and unique properties for use in catalysis, surface-enhanced Raman scattering (SERS) and biomedical applications. We report a chemical approach to reconstruct the morphology of AuAg spiky nanostars using additional metal ions, into nanostructures that exhibits enriched SERS-based chemical sensing. To achieve this, we developed a two-step reduction process involving the simultaneous reduction of gold and silver followed by a successive reduction process. First, AuAg nanostars were synthesized by reducing Au and Ag using a one-pot method. Secondly, Au and Ag ions were separately deposited on the as-prepared AuAg nanostars and reduced. Successive reduction of Ag onto the AuAg nanostar resulted in a layered core-shell nanostructure with minimal mixing of the two metals. The deposition of Au ions onto the AuAg nanostars yielded maximally mixed alloyed nanostructures. There was no significant change in the morphology of the spiky nanostars with the use of high or low Ag feed concentrations or low Au concentrations. However, a new star-like nanostructure was formed as a result of the successive reduction of Au ions at a high feed concentration. The properties evaluated by SERS studies reveals that the as-prepared maximally mixed random alloy outperforms the minimally mixed layered core-shell nanostructures.

High-efficient preparation and screening of electrocatalysts using a closed bipolar electrode array system

High-efficient preparation and screening of electrocatalysts for oxygen reduction reaction (ORR) was realized by a three electrode driving closed bipolar electrode (BPE) array system. As high concentrations of Fe(CN)63−/4− (both 200 mM) existed in the anodic cell of the BPE system and same electrode material was adopted by the BPE anodic pole and driving electrode in anodic cell, the anodic cell performed similar to “good conductor” and the electrochemical behavior of the closed BPE system approximately equal to that of the three-electrode system in cathodic cell. Based on the above property and the parallel array, electrocatalysts containing bimetallic Pt Au and reduced graphene oxide (PtAu-rGO) with varying metal proportion were successfully prepared on the cathodic BPE poles by a two-step reduction process. Graphene oxide was firstly reduced to reduced graphene oxide (rGO) in each cathodic pole by cyclic voltammetry, and then Pt Au with different metal proportion were electrodeposited on the surface of rGO. Afterward, in-situ and high-throughput screening of these electrocatalysts for ORR was carried out based on the electrochemiluminescence (ECL) imaging on the corresponding anodic BPE poles. The screening results were consistent with those of the conventional electrochemical method by testing the catalytic performance one by one very well. This closed BPE array system with one potentiostat not only can prepare multiple catalyst candidates at the same time, but also can evaluate them, simultaneously, which is of great immediate significance to the field of fuel cell.

From sol\u2013gel prepared porous silica to monolithic porous Mg2Si/MgO composite materials

Mg2Si is apart from its conductivity properties expected to be a promising candidate for thermoelectric applications due to its low toxicity, low costs, and the high abundance of its precursor chemicals. Through the addition of a homogeneous distribution of nanoparticles (e.g. MgO) and by reducing the size of Mg2Si to the nanometer regime, it is possible to decrease the thermal conductivity by increasing phonon-interface scattering and, as a result, improve the thermoelectric properties. However, classical approaches do not allow for the synthesis of nanocomposites from Mg2Si and MgO. In this work, a straightforward route is presented towards homogeneously mixed Mg2Si/MgO via a two-step magnesiothermic reduction process starting from sol–gel derived hierarchically organized porous silica. Monolithic materials composed of Mg2Si and MgO in variable molar ratios are built up from a macroporous network of Mg2Si with homogeneously distributed MgO particles exhibiting a crystallite size in the range of 24–37 nm.