《标准电极电位表》纠错180例——兼与Milazzo G和Caroli S商榷

国际生物电化学学会主席、意大利物理化学家 Milazzo G 教授和 Caroli S 编著的,国际纯粹与应用化学会(IUPAC)认可的《标准电极电位表》(Tables of Standard Electrode Potentials),被国际电化学界誉为电极电位的极威著作。全书刊载的2498个数据,在化学诸多领域得到了广泛的应用。但是,笔者首次发现,该书在标准电极电位数据、电极电位元素属性、电极反应可逆性和配合物的配位数方面存在着180例错误(错率7.2%)。对此,本文根据物质的氧化还原性质及标准电极电位的变化规律,进行了较系统的分析和订正。     

Dynamic Multistage Coupling of FeS2/S Enables Ultrahigh Reversible Na–S Batteries

The fundamental challenges that coexisted around sulfur cathode energy storage systems, are the severe polysulfide dissolution and low reactivity resulting in poor reversibility and short cycle life, specifically, in inexpensive sodium ion batteries. Herein, the solution-processed synthesis of ultra-high intimate contacted FeS₂/S architecture is reported and evolution of the dynamic multistage coupling between the FeS₂ and S in sodium–sulfur batteries is revealed. Atomic visualization and in situ spectroscopy conclude that: Na_xFeS₂ (0 <x ≤1) effectively captures sodium polysulfides and promotes the conversion of S₈ to Na₂S₄ to Na₂S₂/Na₂S; simultaneously, the presence of Na₂S₂/Na₂S traps the continuous growth of iron grains during continuously discharging to 0.4 V, thereby boosting the reversibility and high capacity. Moreover, the density functional theory further analyses the unique coupling effect of Na₂S_x with different intermediate states of FeS₂. The electrode with unique structure and dynamic coupling exhibits outstanding cycle reversibility and extremely long life, which delivers a reversible capacity of 860 mAh g⁻¹ after 1000 cycles with no capacity decay at 0.5 A g⁻¹. Even under a practical areal capacity of 4 mAh cm⁻², it still shows pretty-well cycling stability.     

Edge Coordination of Ni Single Atoms on Hard Carbon Promotes the Potassium Storage and Reversibility

Hard carbon is the most promising anode for potassium-ion batteries (PIBs) due to its low cost and abundance, but its limited storage capacity remains a major challenge. Herein, edge coordination of metal single atoms is proved to be an effective strategy for promoting potassium storage in hard carbon for the first time, taking B, N co-doped hard carbon nanotubes anchored by edge Ni-N₄-B atomic sites (Ni@BNHC) as an example. It is revealed that edge Ni-N₄-B can provide active sites for interlayer adsorption of K⁺ and that Ni atoms can facilitate the reversibility of K⁺ storage on N and B atoms. Furthermore, an unprecedentedly reversible K⁺ storage capacity of 694 mAh g⁻¹ at 0.05 A g⁻¹ is realized by introducing commercial carbon nanotubes. This work provides a new perspective for the application of single-atom engineering and the design of high-performance carbon anodes for PIBs.     

Feedback control and the arrow of time

The purpose of this article is to highlight the central role that the time asymmetry of stability plays in feedback control. We show that this provides a new perspective on the use of doubly-infinite or semi-infinite time-axes for signal spaces in control theory. We then focus on the implication of this time asymmetry in modelling uncertainty, regulation and robust control. We point out that modelling uncertainty and the ease of control depend critically on the direction of time. We also discuss the relationship of this control-based time-arrow with the well-known arrows of time in physics.     

Electrochemical behavior of negative electrode of lead-acid cells based on reticulated vitreous carbon carrier

Reticulated vitreous carbon (RVC^®) and RVC^® plated with lead were investigated as carriers for the negative electrode of lead-acid cell. The RVC^® and Pb/RVC^® carriers were pasted with active paste (received from JENOX Ltd., Polish producer of lead-acid batteries) and prepared to be used in lead-acid cell. Comparative study of electrodes based on RVC^® and Pb/RVC^® has been done using constant-current charging/discharging, constant-potential discharging and cycling voltammetry measurements. Scanning electron microscopy (SEM) was employed to determine the morphology of the lead layer deposited on the RVC surface. Hybrid flooded single lead-acid cells containing one negative electrode, based on new type of carrier (RVC^® or Pb/RVC^®), sandwiched between two positive electrodes, based on the Pb-Ca grids, were assembled and subjected to electrochemical tests. It has been found that both materials, RVC^® and Pb/RVC^®, can be used as carriers of negative electrode, but the latter seems to have better influence on the discharge performance.     

Ion Exchange Reversibility of Some Radionuclides on Zirconium Tungstosuccinate and Zirconium Tungstosalicylate at their Solid-Liquid Interfaces

Zirconium tungstosuccinate (ZWSu) and zirconium tungstosalicylate (ZWSa) composites were synthesized by anchoring moieties of succinic acid (SuA) and salicylic acid (SaA) onto zirconium tungstate (ZW), respectively. The produced exchange composites were unambiguously characterized by TGA, DTA, XRD, and FTIR spectroscopy. Thermally stable, amorphous, highly active, and multifunctional inorganic-organic exchangers were produced. The sorption behavior of the hybrid materials for removal of some hazardous radionuclides, ¹³⁴Cs, ⁶⁰Co, and ^152+154 Eu has been studied for covering different pHs, contact time, and concentrations; capacity; 2.6, 3.14, and 4.05 meq/g were accommodated. FORM, PFORM, and PSORM equations were kinetically tested to predict the reaction mechanism. Adsorption isotherms have been constructed at different reaction temperatures (30, 40, 50, 60 ± 1°C). Adsorption of ¹³⁴Cs, ⁶⁰Co, and ^152+154 Eu on the exchangers fit to Langmuir and Freundlich isotherms. The effect of temperature on the equilibrium distribution coefficient values was also investigated, and the thermodynamic parameters were determined; the reverse order kinetics and ion exchange reversibility were moreover indicated.     

The resistance characteristic of the polymer carbon microcoil composite with temperature change

ABSTRACT

Novel polymer carbon microcoil (CMC) composite has been fabricated by the intercalation of polymer material into free volume contained in CMC sheets grown by chemical vapour deposition process. Then the resistance of composite was measured in two-probe method. It was observed that the resistances of the composite have good reversibility as the temperature cyclic changing near the room temperature; in addition, the intercalation of the organic polymers such as polyvinyl alcohol can improve the resistance sensitivity. We propose that the resistance change is dominantly determined by the contact junctions of CMCs in the composite, which gives a reasonable explanation to the reversibility. The study will be used for sensor research.     

Identification of contaminant sources in enclosed spaces by a single sensor

To protect occupants from infectious diseases or possible chemical/biological agents released by a terrorist in an enclosed space, such as an airliner cabin, it is critical to identify gaseous contaminant source locations and strengths. This paper identified the source locations and strengths by solving inverse contaminant transport with the quasi-reversibility (QR) and pseudo-reversibility (PR) methods. The QR method replaces the second-order diffusion term in the contaminant transport equation with a fourth-order stabilization term. By using the airflow pattern calculated by computational fluid dynamics (CFD) and the time when the peak contaminant concentration was measured by a sensor in downstream, the QR method solves the backward probability density function (PDF) of contaminant source location. The PR method reverses the airflow calculated by CFD and solves the PDF in the same manner as the QR method. The position with the highest PDF is the location of the contaminant source. The source strength can be further determined by scaling the nominal contaminant concentration computed by CFD with the concentration measured by the sensor. By using a two-dimensional and a three-dimensional aircraft cabin as examples of enclosed spaces, the two methods can identify contaminant source locations and strengths in the cabins if the sensors are placed in the downstream location of the sources. The QR method performed slightly better than the PR method but with a longer computing time. PRACTICAL IMPLICATIONS: The paper presents a method that can be used to find a gaseous contaminant source location and determine its strength in enclosed spaces with the data of contaminant concentration measured by one sensor. The method can be a very useful tool to find where, what, and how the contamination has happened. The method is also useful for optimally placing sensors in enclosed spaces. The results can be applied to develop appropriate measures to protect occupants in enclosed environments from infectious diseases or chemical/biological warfare agents released by a terrorist.