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Developing oxygen reduction reaction (ORR) catalysts with high activity and low cost is a challenge in the field of electrochemical energy conversion. Here, an efficient catalyst of N-doped carbon with non-precious metals (Mn, Fe, Co, and Ni) designated as MFCN/NC has been prepared by using a simple pyrolysis method. Pyridinic nitrogen, graphitic carbon, MnO, and Fe-Co-Ni nanoparticles, which are efficient for catalyzing the ORR individually or synergistically, are successfully introduced into the composite catalyst. The optimized MFCN/NC catalyst exhibits four-electron reduction of O2 with a more positive ORR onset potential (54 mV) and a more positive half-wave potential (46 mV) than commercial Pt/C. Moreover, MFCN/NC shows remarkable electrocatalytic activity and long-term stability in Na2CO3 electrolysis. The cell voltages at 10 and 100 mA cm−2 are only 0.86 and 1.45 V, respectively, suggesting an energy-saving electrolysis of Na2CO3 to regenerate NaHCO3 and NaOH. [ABSTRACT FROM AUTHOR]

Human health risks associated with drinking water chlorination disinfection have been identified, and the development of new disinfecting methods to minimize the risks with less energy and chemicals is the direction of water treatment industry. In this study, an electrochemical system was investigated for drinking water treatment in an undivided electrochemical reactor using Ti/RuO2–IrO2anode and graphite felt cathode. The reactor configuration was designed in such a way that the angle of the electrodes was adjustable between 0° and 90°. It was found that the laboratory reactor (660 × 620 mm size) with electrodes positioned between 30° and 65° provided satisfactory results at a treatment capacity of 250 L/h water. A pilot plant test was conducted for treatment of Yellow River water using four laboratory-scale reactors in parallel, and the electrochemical treatment was compared with chemical disinfection using sodium hypochlorite, ozone, and potassium permanganate in the pilot plant facility. The results demonstrate that the electrochemical treatment is superior to chemical disinfection using sodium hypochlorite, ozone, and potassium permanganate in terms of removal of taste and odor and formation of disinfection byproducts. [ABSTRACT FROM AUTHOR]

The antibacterial and antifungal activities of three new pyrimidine derivatives, namely, 2,6-bis(4,6-dimethylpyrimidin-2-ylthio)benzene-1,4-diol (1),3,5-bis(4,6-dimethylpyrimidin- 2-ylthio)-2-methylbenzene-1,4-diol (2) and 3,5-bis(4,6-dimethylpyrimidin-2- ylthio)-2-methoxybenzene-1,4-diol (3), synthesised by electrochemical method are presented here. The compounds were screened for their activities against Grampositive and Gram-negative bacteria, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and a pathogenic fungus Aspergillus niger. The results show that these compounds have significant activity against these bacteria and fungus. The minimum inhibitory concentration of compound 1 was determined as 62.5 µg/mL against B. subtilis, 125 µg/mL against E. coli and 250 µg/mL against S. aureus establishing its promising activities higher than susceptible ranges. [ABSTRACT FROM AUTHOR]

An electrochemical process for producing potassium iodate based on oxidation of KI coupled with oxygen reduction reaction in a newly designed cell is reported. By using an Ag-modified oxygen reduction cathode, the proposed cell needed no ion exchange membrane, and the current efficiency for KIO3 was confirmed to be over 96%, the corresponding cell voltage was only 0.7–0.8 V. [ABSTRACT FROM AUTHOR]

Abstract: The layered LiNiO2 cathode material for lithium ion battery was synthesized by ion-exchange reaction at low temperature in air atmosphere. The influence of synthesis conditions on the electrochemical performance of the resulting LiNiO2 was investigated. The LiNiO2 samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and infrared (IR) analysis. The results indicate that low temperature fabricated LiNiO2 powders keep a single layered hexagonal structure and homogenous spheric shape like the raw material NiOOH. Charge and discharge tests show that the resultant LiNiO2 exhibits good electrochemical properties. The first charge and discharge capacities of the sample are 183.4 mA h g−1 and 169.5 mA h g−1 at 0.5 mA cm−2, respectively. Galvanic charge/discharge and cyclic voltammetry tests reflect that LiNiO2 electrode exhibits good cycle reversibility. [Copyright &y& Elsevier]

Residual chlorine has a bactericidal effect, but it may react with natural organic matter in water to produce harmful substances. In this work, we report an efficient residual chlorine removal filter with activated carbon fiber (ACF) as adsorption carrier and CuO as residual chlorine degradation catalyst. Experimental results show that CuO has high catalytic efficiency and no attenuation of catalytic performance in 2924 h. The CuO is loaded on the surface of ACF by dipping-calcinating method. When the loading rate is 1.5%, the CuO distribution is uniform without defects and agglomeration. Continuous-flow experiment result shows that 1.5%-CuO/ACF filter can treat water amount 2.2 times as long as that for single ACF filter (residual chlorine concentration < 0.1 mg/L). Weak acidity and rising temperature can improve the reaction activity and increase the degradation amount of residual chlorine. The composite filter has excellent adsorption performance for Cu2+, showing the Cu2+ concentration in the produced water is less than 0.1 mg/L after filter treatment, which is in line with the National Drinking Water Standards, and in agreement with the Standard for Safety Assessment of Water Transmission and Distribution Equipment and Protective Materials for Drinking Water (GB/T17219-1998) of Immersion Experiment, indicating that 1.5%-CuO/ACF filter has good stability and safety. [ABSTRACT FROM AUTHOR]

Adsorption, sample preservation, and cross‐contamination are the major impediments to the accurate and sensitive analysis of low‐level mercury samples. Common measures to deal with this issue are to use Teflon, quartz, or borosilicate glass bottles for sampling, standard solution and sample preservation with oxidative chemicals, to prepare standard solutions daily and to use dedicated glassware. This paper demonstrates that these measures are neither efficient nor effective. Two common laboratory sample containers (borosilicate volumetric glass flasks and polypropylene tubes) are investigated for the preparation and preservation of water samples and standard solutions of 0.2–1 µg L−1 with 2% HNO3. Mercury adsorption rates of 6–22% are observed within 30 min and after 48 days, the adsorption is greater than 98%. In stark contrast, no adsorption is found during a testing period of 560 days when the solutions are subject to potassium permanganate‐persulfate digestion. New glass flasks and polypropylene bottles are free of mercury contamination but reused flasks are a major source of mercury cross‐contamination. To minimize adsorption and cross‐contamination, standard solutions are treated by potassium permanganate‐persulfate or BrCl digestion, and each individual sample and standard solution should be stored and prepared in single‐use polypropylene bottle, without transference. [ABSTRACT FROM AUTHOR]

Sustainable water electrolysis powered by renewable energy requires cost-efficient, effective, and robust catalysts. This study utilizes NiMoFeO and its nitrogen-doped carbon-coated (NC) derivatives NiMoFe@NC, as advanced OER and HER catalysts, respectively. The derivative fabrication not only simplifies catalyst synthesis but also notably enhances the stability of the HER catalyst through carbon coating. The outstanding OER performance of NiMoFeO is attributed to high-valence metals, while the enhanced HER activity of NiMoFe@NC arises from synergies effect from NiFe and MoO 2. At 10 mA cm−2, NiMoFeO showcased a low OER overpotential of 197 mV, and NiMoFe@NC displayed an extremely low HER overpotential of 8 mV. At 100 mA cm−2 and 27 °C, the NiMoFeO(+)//NiMoFe@NC(−) exhibited a voltage of 1.69 V, outperforming the RuO₂(+)//Pt/C (−) (1.77 V). Notably, over 1000 cycles of repetitive ON/OFF electrolysis, the voltage of NiMoFeO(+)//NiMoFe@NC(−) merely increased 0.01 V, confirming the exceptional potential of these catalysts for hydrogen production compatible with renewable energy. [Display omitted] • Using the same precursor for derivative fabrication simplifies the catalyst synthesis. • NiMoFeO and NiMoFe@NC exhibit significant activity in OER and HER, respectively. • The carbon coating notably enhances HER catalyst stability of NiMoFe@NC. • NiMoFeO(+)//NiMoFe@NC(−) exhibits lower voltage than RuO 2 (+)//Pt/C (−) in the same condition. • NiMoFeO(+)//NiMoFe@NC(−) display outstanding stability during ON/OFF electrolysis. [ABSTRACT FROM AUTHOR]

Electrosynthesis of H2O2 via both pathways of anodic two-electron water oxidation reaction (2e-WOR) and cathodic two-electron oxygen reduction reaction (2e-ORR) in a diaphragm-free bath can not only improve the generation rate and Faraday efficiency (FE), but also simplify the structure of the electrolysis bath and reduce the energy consumption. The factors that may affect the efficiency of H2O2 generation in coupled electrolytic systems have been systematically investigated. A piece of fluorine-doped tin oxide (FTO) electrode was used as the anode, and in this study, its catalytic performance for 2e-WOR in Na2CO3/NaHCO3 and NaOH solutions was compared. Based on kinetic views, the generation rate of H2O2 via 2e-WOR, the self-decomposition, and the oxidative decomposition rate of the generated H2O2 during electrolysis in carbonate electrolytes were investigated. Furthermore, by choosing polyethylene oxide-modified carbon nanotubes (PEO-CNTs) as the catalyst for 2e-ORR and using its loaded electrode as the cathode, the coupled electrolytic systems for H2O2 generation were set up in a diaphragm bath and in a diaphragm-free bath. It was found that the generated H2O2 in the electrolyte diffuses and causes oxidative decomposition on the anode, which is the main influent factor on the accumulated concentration in H2O2 in a diaphragm-free bath. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-ion batteries have attracted a lot of attention owing to their cost effectiveness and plentiful resources, but less research has been conducted on the aspect of high volumetric energy density, which is crucial to the space available for the batteries in practical applications. In this work, highly crystalline V2O5 microspheres were self-assembled from one-dimensional V2O5 nanorod structures by a template-free solvothermal method, which were used as cathode materials for zinc-ion batteries with high performance, enabling fast ion transport, outstanding cycle stability and excellent rate capability, as well as a significant increase in tap density. Specifically, the V2O5 microspheres achieve a reversible specific capacity of 414.7 mAh g−1 at 0.1 A g−1, and show a long-term cycling stability retaining 76.5% after 3000 cycles at 2 A g−1. This work provides an efficient route for the synthesis of three-dimensional materials with stable structures, excellent electrochemical performance and high tap density. [ABSTRACT FROM AUTHOR]

Hydrogen production through alkaline water electrolysis holds great promise as a scalable solution for renewable energy storage and conversion. The development of non-precious metal-based electrocatalysts with low-overpotential for alkaline water electrolysis is essential to decrease the cost of electrolysis devices. Although the Ni-based and Fe-based electrocatalysts have been commercially employed in the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), it is imperative to persistently pursue the advancement of highly efficient electrocatalysts with enhanced current density and fast kinetics. This feature article overviews the progress of NiMo HER cathodes and NiFe OER anodes in the traditional alkaline water electrolysis process for hydrogen production, including the detailed mechanisms, preparation strategies, and structure–function relationship. Moreover, recent advances of Ni-based and Fe-based electrodes in the process of novel alkaline water electrolysis, involving small energetic molecule electro-oxidation and redox mediator decoupled water electrolysis, are also discussed for hydrogen production with low cell voltage. Finally, the perspective of these Ni-based and Fe-based electrodes in the mentioned electrolysis processes is proposed. [ABSTRACT FROM AUTHOR]

A 3D honeycomb-like porous carbon material featured with zinc and nitrogen co-doped zincophilic sites and nano-pools structure was fabricated and used as highly reversible and dendrite-free zinc anode of zinc-ion batteries. [Display omitted] The zinc-ion battery (ZIB) has been extensively researched as one of the promising electrochemical power sources. However, the problem of Zn-dendrite formation during repeated plating and stripping process seriously hinders the development of ZIBs. Herein, three-dimensional (3D) honeycomb-like porous carbon (HPC) with co-doping of zinc and nitrogen is prepared through confining growth of nanoscale zeolite imidazole framework-8 (ZIF-8) on the well-designed nano-pools walls of HPC followed by pyrolysis at 600 ℃ to obtain the final product ZnN/HPC-600, which exhibits large surface area and abundant zincophilic interfaces, ensuring homogeneous distribution of electronic field and low polarization during cycling process. Importantly, ZnN/HPC-600 facilitates the uniform distribution and migration of Zn2+ in this nano-pools structure, avoiding the growth of dendritic Zn crystal during charging stage. The symmetric and asymmetric cells with Zn/ZnN/HPC-600 anodes are assembled, demonstrating excellent cycling reversibility, good rate performance and long-term stability. Besides, a Zn||MnO 2 full cell with Zn/ZnN/HPC-600 anode also exhibits robust cycling stability, fast reaction kinetics and almost 100 % coulombic efficiency. This work offers a novel and efficient carbonaceous nano-pools strategy to realize dendrite-free zinc anode in ZIBs. [ABSTRACT FROM AUTHOR]

Due to the technology advancement and the large-scale application of lithium-ion batteries in recent years, the market demand for lithium is growing rapidly and the availability of land lithium resources is decreasing significantly. As such, the focus of lithium extraction technologies has shifted to water lithium resources involving salt-lake brines and sea water. Among various aqueous recovery technologies, the lithium ion-sieve (LIS) technology is considered the most promising one. This is because LISs are excellent adsorbents with high lithium uptake capacity, superior lithium selectivity and good cycle performance. These attributes have enabled LISs to separate lithium effectively from aqueous solutions containing different ions. The present work reviews the latest development in LIS technology, including the chemical structures of ion-sieves, the corresponding lithium adsorption/desorption mechanisms, the ion-sieves preparation methods, and the challenges associated with the lithium recovery from aqueous solutions by the LIS batteries. Besides, some common LIS composite materials forming technologies, including granulation, foaming, membrane and fiber formation, and magnetization, which are used to overcome the shortcomings in industrial column operations, are also explored. [ABSTRACT FROM AUTHOR]

The concentration of 5-hydroxyindole acetic acid (5-HIAA), the major metabolite of serotonin, might be the diagnosis basis for some cranial nerve pathology. An oxidized glassy carbon electrode (named OGCE) was employed to detect 5-HIAA with electrochemical methods. Multi-peaks appeared from the second cycle in range of 0.10–0.55 V (vs. AgCl/Ag) were assigned to the oxidative intermediates and products of 5-HIAA after the electrochemically driven oxidation at over 0.6 V in the first cycle. Kinetics studies show that all of these electrode reactions are adsorption-controlled processes, which are contributed to the strong hydrogen-bond interaction of these intermediates with the negatively charged hydroxyl and carboxyl groups on the surface of OGCE. Based on the square wave voltammetry (SWV) method, the linear relationship was shown between the peak current at 0.7 V and the concentration of 5-HIAA in range of 1.56–58.6 μmol/L, so 5-HIAA could be determined with limit of 0.917 μmol/L ( S/N = 3) even certain interference were co-existed. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF) derived porous carbon materials have been widely applied as active materials for supercapacitors due to their large specific surface area and ordered pore structure. This paper presents a facile and effective strategy to regulate the morphology of a zinc-based metal–organic framework (Zn-trimesic acid, Zn-BTC) by adjusting the ethanol content in a solvent, which can effectively change the pore structure of Zn-BTC derived porous carbon (PC). The optimal PC prepared in 50% ethanol displays a rodlike structure with a large specific surface area (SSA) of 1930 m2 g−1 and an average pore size of 2.9 nm. This material shows an excellent rate performance with 78.8% capacitance retention when the current density increases from 1 A g−1 to 100 A g−1 and outstanding electrochemical stability with only 2.2% decline of capacitance after 200 000 cycles at 50 A g−1. Moreover, the assembled symmetrical capacitor shows a high energy density of 16.09 W h kg−1 at 698 W kg−1 and 11.89 W h kg−1 at a high power density of 41.56 kW kg−1. This method would provide a new pathway for the preparation of carbon materials with an adjustable pore size for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Highlights: [•] A flat and compact BiFSn-0.3V was electro-deposited with Sn2+ coexisted in electrolyte. [•] Sn2+ affected the formation of the metal ion deficient layer in plating process. [•] BiFSn-0.3V has improved working window and reproducibility compared with BiFE. [ABSTRACT FROM AUTHOR]