Electrooxidation of Aqueous p-Methoxyphenol on Lead Oxide Electrodes

Oxidation of p-methoxyphenol (pmp) in aqueous solution on bismuth-doped lead oxide was studied, and the effects of the initial pmp concentration, applied potential and hydrodynamic conditions upon the oxidation rate were identified. Under all conditions studied, the concentration decay of pmp during electrooxidation follows first—order reaction kinetics. Through analysis of rotating ring-disc currents, the faradaic efficiencies for oxidation at various concentrations of pmp in solution were determined. Using u.v.—vis. and H¹RMN spectroscopy for solution analysis, it is shown that partial oxidation of pmp occurs in chloride-free aqueous solutions. The principal products were p-benzoquinone and maleic acid, with low production of CO₂ up to 1000 C dm^–3 charge. Mineralization to CO₂ was considerably improved upon addition of chloride ions to the solution. In situ FTIR spectra of the electrode surface during electrolysis indicated that the presence of chloride ions enhances the mineralization of pmp by reaction of benzoquinone with anodically generated hypochlorite.     

Studies of the adsorption of tetrasulfonated phthalocyanines on graphite substrate

The adsorption of iron and cobalt terasulfonated phthalocyanines (TsPcs) on ordinary pyrolytic graphite has been investigated as a function of pH and ionic strength of the adsorption solution as well as the potential. The charge corresponding to the voltammetric redox peaks of adsorbed complexes was used as a measure of the surface concentration. Adsorption of CoTsPc occurs readily from its freshly prepared aqueous solutions and is generally independent of pH. For FeTsPc, however, adsorption does strongly depend on pH. High surface coverage is achieved only from acid solutions rather than from pure water and alkaline solutions. This can be explained in terms of the form(s) of the complexes existing in the solution phase in the presence of air. uv-Visible spectroscopic studies coupled with the addition of CN⁻ to the macrocycle solutions provide evidence that in pure water and alkaline solutions FeTsPc exists predominantly in the μ-oxo form (FeTsPc)₂O, which seems not to favor the adsorption process. No evidence of the μ-oxo complex was found for FeTsPc in acid solutions and CoTsPc in aqueous solutions over the pH range examined (1–13). The adsorption of FeTsPc was at maximum when the potential was held at −0.55 V vs sce in 0.1 M NaOH.     

Identification of the adsorbed intermediate of the electrooxidation of chloride by the cv technique

The adsorbed intermediate of the chloride electrochemical oxidation process on a RuO₂/TiO₂ mixed oxide electrode was studied by cv technique in a large range of sweep rate. The existence of a reverse adsorption peak was directly proved by the preliminary results summarised here. The electrocatalytic activity of different electrodes used as working electrode for chloride oxidation can be qualified by the cv method.     

Catalysis of Salicylaldehydes and Two Different C?H Acids with Electricity: First Example of an Efficient Multicomponent Approach to the Design of Functionalized Medicinally Privileged 2‐Amino‐4H‐Chromene Scaffold

Electrochemically induced multicomponent transformation of salicylaldehydes and two different C H acids in alcohols in an undivided cell in the presence of sodium bromide as an electrolyte results in the efficient and selective formation of diversely functionalized, medicinally privileged 2‐amino‐4H‐chromene scaffolds in 65–86% yields. The developed electrocatalytic system affords the distinction between two C H acids according to their reactivity, and offers an efficient approach to the 2‐amino‐4H‐chromene scaffold with a predefined arrangement of desired substituents. The electrocatalytic multicomponent reaction smoothly proceeds with salicylaldehydes bearing both electron‐donating and electron‐withdrawing groups. Thus, fifteen previously inaccessible, close structural analogues of the tumor antagonists HA14‐1 and MX58151 have been synthesized. The electrocatalytic process was found to be advantageous in terms of selectivity and yields compared to classic chemical base catalysis, and includes a remarkable mechanistic feature that is promising for the further development of 2‐amino‐4H‐chromene chemistry. The application of this convenient electrocatalytic multicomponent method to the formation of medicinally relevant 2‐amino‐4H‐chromenes is also beneficial from the viewpoint of diversity‐oriented large‐scale processes and represents a novel, facile and environmentally benign synthetic concept for multicomponent reaction strategy.     

对乙酰氨基酚在n-丁基吡啶六氟磷酸盐修饰碳糊电极上的灵敏测定（英文）

将离子液体（n-丁基吡啶六氟磷酸盐,[BuPy][PF6]）与石墨粉混合,制备了离子液体修饰碳糊电极（CILE）.在0.1mol/L醋酸盐缓冲溶液中（pH 4.7）,采用循环伏安法（CV）、方波伏安法（SWV）及计时库仑分析法研究了对乙酰氨基酚的电化学行为.结果表明：CILE对对乙酰氨基酚的氧化还原具有明显的电催化作用;在0.1V/s扫速下,对乙酰氨基酚的氧化还原峰峰电位差（ΔEP）为88mV;扩散系数（D）为1.214×10-7 cm2/s.对乙酰氨基酚的氧化峰电流与其浓度在0.5～10.0μmol/L范围内呈线性关系（r=0.998 8）,检出限为0.01μmol/L（S/N=3）.该修饰电极成功用于片剂与尿样中对乙酰氨基酚含量的检测,且具有制作成本低、稳定性好、易于重复和制备等特点.     

Oxidation State Modulation of Bismuth for Efficient Electrocatalytic Nitrogen Reduction to Ammonia

Electrocatalytic nitrogen reduction reaction (NRR) is a promising strategy for ammonia (NH₃) production under ambient conditions. However, it is severely impeded by the challenging activation of the NN bond and the competing hydrogen evolution reaction (HER), which makes it crucial to design electrocatalysts rationally for efficient NRR. Herein, the rational design of bismuth (Bi) nanoparticles with different oxidation states embedded in carbon nanosheets (Bi@C) as efficient NRR electrocatalysts is reported. The NRR performance of Bi@C improves with the increase of Bi⁰/Bi³⁺ atomic ratios, indicating that the oxidation state of Bi plays a significant role in electrochemical ammonia synthesis. As a result, the Bi@C nanosheets annealed at 900  ° C with the optimal oxidation state of Bi demonstrate the best NRR performance with a high NH₃ yield rate and remarkable Faradaic efficiency of 15.10  ± 0.43% at − 0.4 V versus RHE. Density functional theory calculations reveal that the effective modulation of the oxidation state of Bi can tune the p-filling of active Bi sites and strengthen adsorption of *NNH, which boost the potential-determining step and facilitate the electrocatalytic NRR under ambient conditions. This work may offer valuable insights into the rational material design by modulating oxidation states for efficient electrocatalysis.     

Fabrication of Co doped MoS2 nanosheets with enlarged interlayer spacing as efficient and pH-Universal bifunctional electrocatalyst for overall water splitting

Exploring inexpensive and active bifunctional electrocatalysts to produce hydrogen and oxygen from water at all pHs is highly desirable. Herein, we report a facile one-step method to prepare vertically aligned Co doped MoS₂ nanosheets with extended interlayer distance on carbon cloth (Co–MoS₂@CC) for full hydrolysis in both alkaline and acidic medium. Co–MoS₂@CC exhibits long-term durability with overpotentials of 56.6 mV and 130 mV for hydrogen generation and 242 mV and 201 mV for oxygen production at 10 mA cm^?2 in basic and acidic conditions, respectively. Moreover, we achieve low voltages of 1.585 V and 1.55 V in basic and acidic conditions respectively for the overall water splitting. We assume that such excellent property of Co–MoS₂@CC may be ascribed to the uncovering of more active sites and high porosity resulted from Co doping, which boosts the conductivity and thus reduces MoS₂ hydrogen adsorption free energy in HER, as well as benefits to catalytic active sites in OER. This one-step doping approach opens up new ways to regulate the intrinsic catalytic activity to catalyze total hydrolysis at all PHs.     

Reconstructed Water Oxidation Electrocatalysts: The Impact of Surface Dynamics on Intrinsic Activities

Electroreduction of small molecules such as H₂O, CO₂, and N₂ for producing clean fuels or valuable chemicals provides a sustainable approach to meet the increasing global energy demands and to alleviate the concern on climate change resulting from fossil fuel consumption. On the path to implement this purpose, however, several scientific hurdles remain, one of which is the low energy efficiency due to the sluggish kinetics of the paired oxygen evolution reaction (OER). In response, it is highly desirable to synthesize high-performance and cost-effective OER electrocatalysts. Recent advances have witnessed surface reconstruction engineering as a salient tool to significantly improve the catalytic performance of OER electrocatalysts. In this review, recent progress on the reconstructed OER electrocatalysts and future opportunities are discussed. A brief introduction of the fundamentals of OER and the experimental approaches for generating and characterizing the reconstructed active sites in OER nanocatalysts are given first, followed by an expanded discussion of recent advances on the reconstructed OER electrocatalysts with improved activities, with a particular emphasis on understanding the correlation between surface dynamics and activities. Finally, a prospect for clean future energy communities harnessing surface reconstruction-promoted electrochemical water oxidation will be provided.     

Molecule-confined modification of graphitic C3N4 to design mesopore-dominated Fe-N-C hybrid electrocatalyst for oxygen reduction reaction

To design inexpensive carbon catalysts and enhance their oxygen reduction reaction (ORR) activity is critical for developing efficient energy-conversion systems. In this work, a novel Fe-N-C hybrid electrocatalyst with carbon nanolayers-encapsulated Fe₃O₄ nanoparticles is synthesized successfully by utilizing the molecular-level confinement of graphitic C₃N₄ structures via hemin biomaterial. Benefiting from the Fe-N structure prevalent on the carbon nanosheets and large mesopore-dominated specific surface area, the synthesized catalyst under optimized conditions shows excellent electrocatalytic performance for ORR with an E_ORR at 1.08 V versus reversible hydrogen electrode (RHE) and an E_1/2 at 0.87 V vs. RHE, and outstanding long-term stability, which is superior to commercial Pt/C catalysts (E_ORR at 1.04 V versus RHE and E_1/2 at 0.84 V versus RHE). Moreover, the low hydrogen peroxide yield (<11%) and average electron transfer number (~3.8) indicate a four-electron ORR pathway. Besides, the maximum power density of the home-made Zn-air battery using the obtained catalyst is 97.6 mW cm⁻². This work provides a practical route for the synthesis of cheap and efficient ORR electrocatalysts in metal-air battery systems.     

Liquid‐Phase Exfoliated Indium–Selenide Flakes and Their Application in Hydrogen Evolution Reaction

Single‐ and few‐layered InSe flakes are produced by the liquid‐phase exfoliation of β‐InSe single crystals in 2‐propanol, obtaining stable dispersions with a concentration as high as 0.11 g L⁻¹. Ultracentrifugation is used to tune the morphology, i.e., the lateral size and thickness of the as‐produced InSe flakes. It is demonstrated that the obtained InSe flakes have maximum lateral sizes ranging from 30 nm to a few micrometers, and thicknesses ranging from 1 to 20 nm, with a maximum population centered at ≈5 nm, corresponding to 4 Se–In–In–Se quaternary layers. It is also shown that no formation of further InSe‐based compounds (such as In₂Se₃) or oxides occurs during the exfoliation process. The potential of these exfoliated‐InSe few‐layer flakes as a catalyst for the hydrogen evolution reaction (HER) is tested in hybrid single‐walled carbon nanotubes/InSe heterostructures. The dependence of the InSe flakes' morphologies, i.e., surface area and thickness, on the HER performances is highlighted, achieving the best efficiencies with small flakes offering predominant edge effects. The theoretical model unveils the origin of the catalytic efficiency of InSe flakes, and correlates the catalytic activity to the Se vacancies at the edge of the flakes.