例谈对选择传统与新型化学器材的思考

随着社会的发展,新型的化学器材层出不穷,面对教材中化学实验仍使用传统的实验器材的现状,化学教师应该从实验的目的性、观察性和拓展性三方面综合考虑,选择相应的实验器材。以天平的使用、合金熔点的验证、中和反应的探究、蜡烛燃烧产物的验证等实验为案例,阐述教师在教学中应在两者之间进行合理的选择和应用,充分发挥化学实验的教学功能。

初中化学实验器材的改进与创新研究——以氧气的制取和性质实验为例

各种版本的初中化学教材中,都设置和安排了许多实验。但由于部分传统实验器材的不完善、传统实验设计的不合理性、书本知识中心论以及教师对化学实验器材改进及创新的严重忽视、缺乏对实验创新的教研等,严重影响实验的预期效果与教学的有效性。文章以＂氧气的制取和性质实验＂为例,通过文献查找、实践研究,系统分析了当前实验器材改进与创新中存在的主要问题,并围绕问题,进行了一系列的深入研究与实践。

Research progress on carbon-based zinc-ion capacitors

Zinc-ion capacitors(ZICs),which consist of a capacitor-type electrode and a battery-type electrode,not only possess the high power density of supercapacitors and the high energy density of batteries,but also have other advantages such as abundant resources,high safety and environmental friendliness.However,they still face problems such as insufficient specific capacitance,a short cycling life,and narrow operating voltage and temperature ranges,which are hindering their practical use.We provide a comprehensive overview of the fundamental theory of carbon-based ZICs and summarize recent research progress from three perspectives:the carbon cathode,electrolyte and zinc anode.The influence of the structure and surface chemical properties of the carbon materials on the capacitive performance of ZICs is considered together with theoretical guidance for advancing their development and practical use.

Co-intensification of gold leaching with heavy metals and hydrogen peroxide

Co-intensification was researched to accelerate gold leaching with regards to its electrochemical nature by using anodic intensifiers of heavy metal ions (Pb2+,Bi3+,Tl+,Hg2+ and Ag+) on the basis of hydrogen peroxide assistant leaching on three different types of materials which were classified as a refractory sulphide gold concentrate,an easily leachable sulphide gold concentrate,and a low grade oxide gold ore according to their leaching characteristics.The results showed that,favorable co-intensification effects on the three materials were obtained and leaching time of gold was effectively shortened to no longer than 12 h from 16 to 24 h for hydrogen peroxide assistant leaching.For the five tested heavy metal ions,Bi3+and Tl+ presented co-intensifying effect on all the three materials,and Hg2+ caused co-intensifying effect on both refractory and easily leachable sulphide gold concentrates,and Pb2+ and Ag+ only had co-intensifying effect on the easily leachable sulphide gold concentrate.

A micro-sphere catalyst complex with nano CaCO_3 precursor for hydrogen production used in ReSER process

This paper describes the preparation and evaluation of a micro-sphere catalytic complex for the hydrogen production in a Reactive Sorption Enhanced Reforming （ReSER） process. The catalytic complex made by a spray technique has a dual function containing Ni as a catalytic material and CaO as an adsorption material used in the ReSER process. The attrition characteristics of the catalytic complex are acceptable for the commercial used. The nano GaCO3 material used as a precursor of CaO showed a desirable durability with a CO2 sorption capacity of 0.6 mol CO2/kg after 10 repeating cycles under the carbonation temperature of 600 ℃, a CO2 partial pressure of 0.02 MPa, and a calcination temperature of 750 ℃ in N2 measured by a thermal gravimetric analyzer. The testing of the catalytic complex for ReSER showed a hydrogen yield of over 95 % （v/v） in the laboratory fixed fluidized bed reactor. The catalytic system has an attractive prospect in the ReSER process for hydrogen production, especially in the fluidized mode where reactor and regenerator combined in a cycling process.

Recent advances in ionic liquid-based electrochemical biosensors

Ionic liquids （ILs） have been generally described as molten salts which are composed of asymmetric cations and anions. They exist in liquid state below 100 ℃. Both ILs and their composite materials have been widely used in various fields. Attributed to the outstanding properties including the thermal and chemical stabilities, the negligible volatility, the high ionic conductivity, the wide electrochemical window, and the easy design in the construction, ILs have been applied in electrochemical applications including the electrocatalysis, the electrosynthesis, the electrodeposition, the electrochamical devices and sensors. In addition to the application in electrochemical sensors, ILs have also been used in biosensors because of their biocompatibiciy. Here, we review the recent devel- opments for the applicaitons of ILs in electrochemical sensors and biosensors, including the corresponding properties of ILs suitable for electrochemical sensors. Electrochemical biosensors constructed by numorous composites are the emphasis in the review.

A review of negative electrode materials for electrochemical supercapacitors

With increasing demands for clean and sustainable energy, the advantages of high power density, high efficiency, and long life expectancy have made supercapacitors one of the major emerging devices for electrochemical energy storage and power supply. However, one of the key challenges for SCs is their limited energy density, which has hindered their wider application in the field of energy storage. Despite significant progress has been achieved in the fabrication of high-energy density positive electrodes materials, negative electrode materials with high capacitance and a wide potential window are relatively less explored. In this review, we introduced some new negative electrode materials except for common carbon-based materials and what's more, based on our team's work recently, we put forward some new strategies to solve their inherent shortcoming as electrode material for SCs.

High-efficiency room temperature phosphorescence from amorphous metal-free copolymers

Photofunctional materials with room-temperature phosphorescence（RTP）commonly appeared in expensive metal-coordination complexes and rare-earth-based compounds.Recently,the metal-free organic RTP materials have been paid growing attention from scientific community because of the ease of molecular design,low cost as well as potential applications in molecular switches,chemical sensors and biological imaging.To date,efficient RTP materials with high quantum yield are still very limited due to the T_1-S_0 spinforbidden process and weak spin-orbital coupling.Current mechanism based on crystallization-induced or aggregationinduced phosphorescence may serve as an effective way to enhance the RTP[1,2];

Side-chain effect of organic semiconductors in OFET-based chemical sensors

Organic field-effect transistors（OFETs） offer great potential applications in chemical and biological sensing for homeland security,environmental monitoring,industry manufacturing,and medical/biological detection. Many studies concentrate on sensitivity and selectivity improvement of OFET-based sensors. We report four organic semiconductors with different alkyl side chain lengths but the same π-conjugated core structure for OFETs. Our work focuses on the molecular structure of organic semiconductors（OSCs）. Alkyl side chains can hinder the diffusion of ammonia into the OSCs layer,which blocks the interaction between ammonia and conducting channel. The result also reveals the relationship between the alky chain and the film thickness in sensitivity control. These results are expected to be a guide to the molecular design of organic semiconductors and the choice of OSCs.

One-step electrodeposition fabrication of Ni_3S_2 nanosheet arrays on Ni foam as an advanced electrode for asymmetric supercapacitors

Ni3S2 nanosheet(NS) arrays on Ni foam were fabricated by a simple one-step electrodeposition strategy, and used as a kind of electrode material for asymmetric supercapacitors. The Ni3S2 NS arrays are interconnected, which can be regarded as bridges between these individual nanoparticle units. The electrochemical performances were evaluated by cyclic voltammetry and chronopotentiometry techniques in a three-electrode system. The Ni3S2 NS arrays display a specific capacitance of 773.6 F g^-1 at 1 A g^-1, and excellent rate property of 84.3% at 10 A g^-1. The performance of the Ni3S2 NS arrays was further investigated in an asymmetric supercapacitor for potential practical application. The asymmetric supercapacitor using the Ni3S2 electrode and reduced graphene oxide electrode as positive and negative electrodes, respectively, exhibits an energy density of 41.2 W h kg^-1 at 1.6 kW kg^-1. When up to 16 kW kg^-1, it holds 25.3 W h kg^-1.These excellent electrochemical performances are attributed to the improved electronic conductivity and rich redox reaction sites from Ni3S2 NS arrays. Our results indicate that the Ni3S2 NS arrays have great potential for supercapacitors.

Nanotube-like hard carbon as high-performance anode material for sodium ion hybrid capacitors

Sodium ion hybrid capacitors（SIHCs） are of great concern in large-scale energy storage applications due to their good energy-and-power characteristic, as well as abundant reserves and low cost of sodium. However, the sluggish faradaic kinetics of anode materials severely limit the overall electrochemical performance of SIHC devices. Herein, we report an application of nanotube-like hard carbon（NTHC）anode material prepared by high-temperature carbonization（1150℃） of polyaniline（PANI） nanotubes for high-performance SIHCs. As a result, the assembled sodium ion half-cell with NTHC shows a high reversible capacity of 419.5 mA h g^-1at 0.05 A g^-1and a good rate performance of 74.6 mA h g^-1 at 2.5 A g^-1 in a potential window of 0-2 V（vs. Na/Na^＋）. On this basic, a SIHC using such NTHC as anode and a high-capacity activated carbon（APDC） as cathode is fabricated, which exhibits a high energy density of 133.0 W h kg^-1 at 2850 W kg^-1and still remains 100.9 W h kg^-1 at 14,250 W kg^-1. Within the potential range of 1.5-3.5 V, the SIHCs display an outstanding cycling stability tested at 2 A g^-1 with a good capacity retention of 82.5% even after 12,000 cycles.

Electrochemical capacitors based on the composite of graphene and nickel foam

An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide （GO）, and the composite of GO and nickel foam （NF） （GO/NF） was fabricated by ultrasonication-vacuum-assisted deposition of an aqueous solution of GO on NF. After chemical or thermal reduction, the composite of reduced GO and nickel foam （rGO/NF） was obtained. The electrochemical capacitance performance of rGO/NF was investigated using cyclic voltammetry and gal- vanostatic charge/discharge measurements. The chemically reduced rGO/NF composite （C-rGO/NF） exhibited high specific capacitance of 379 F/g at 1.0 A/g and 266.5 F/g at 10 A/g. We also prepared thermally reduced graphene oxide at 473 K in or- der to illuminate the difference in effect between the chemical and low-temperature thermal reduction methods on electro- chemical properties. The cycling performance of thermally reduced rGO/NF composite （T-rGO/NF） and C-rGO/NF had ~91% and ~95% capacitance retention after 2000 cycles in a 6 mol/L KOH electrolyte, respectively. Electrochemical experiments in- dicated that the obtained rGO/NF has very good capacitive performance and could be used as a potential application of elec- trochemical capacitors. Our work revealed high electrochemical capacitor performance of rGO/NF composite and provided a facile method of rGO/NF preparation.

High-performance aluminum-polyaniline battery based on the interaction between aluminum ion and-NH groups

Aluminum-ion batteries(AIBs)are a type of promising energy storage device due to their high capacity,high charge transfer efficiency,low cost,and high safety.However,the most investigated graphitic and metal dichalcogenide cathodes normally possess only a moderate capacity and a relatively low cycling stability,respectively,which limit the further development of high-performance AIBs.Here,based on the results of first principles calculations,we developed a polyaniline/graphene oxide composite that exhibited outstanding performances as a cathode material in AIBs(delivering 180 mA h g^−1 after 4000 cycles),considering both the discharge capacity and the cycling performance.Ex-situ characterizations verified that the charge storage mechanism of polyaniline depended on the moderate interactions between−NH in the polyaniline chain and the electrolyte anions,such as AlCl4^−.These findings lay the foundation of the development of high-performance AIBs based on conducting polymers.

Fabrication of hybrid Co_3O_4/NiCo_2O_4 nanosheets sandwiched by nanoneedles for high-performance supercapacitors using a novel electrochemical ion exchange

Electrochemical ion exchange has been used to tailor the composition of transition metal oxides （Co3O4） electrode with enhanced capacity while maintaining its crystal structure and morphology. Specifically, Ni ions were incorporated to C03O4 nanosheets sandwiched by nanoneedles to form Co3O4/NiCo2O4 composite. As positive electrode for supercapacitors, the Co3O4/NiCo2O4 composite presents a high areal capacitance of 3.2 F cm^-2 （1060 F g^-1） at a current density of 5 mA cm^-2 and outstanding rate capability as well as long cycle stability. Moreover, the assembled aqueous asymmetric supercapacitor based on Co3O4/NiCo2O4//carbon cloth electrodes delivers a considerable energy density of 3.0 mW hcm^-3 at power density of 136 mW cm^-3, and high rate capability （85% retention at a current density of 30 mA cm^-2）. A safety light composed of ten green LEDs in parallel was lit for -360 s using two identical supercapacitors in series, indicating a promising practical application.