Developments in electrode materials for wastewater treatment

This review provides a current opinion about the most recent advances in the development of novel materials (i.e., anodes and cathodes), as well as new synthesis methodologies, which have been used in water and wastewater treatment by electrochemically driven oxidation technologies. The first section focuses on the advances to produce novel anodic materials comprising the active anodes — which play a key role in direct and indirect oxidation and the nonactive materials — which attract attention due to their high capacity to generate hydroxyl radicals. The second section describes recent progress on the novel emerging cathodic materials that are directly related to in situ electrogeneration of oxidants and are commonly applied in the electro-Fenton technology. Finally, the perspectives and prospects of these novel electrode materials for environmental applications are given.     

Recent trends and advances in microbial electrochemical sensing technologies: An overview

Microbial electrochemical systems utilize the electrochemical interaction between microorganisms and electrode surfaces to convert chemical energy into electrical energy, offering a promise as technologies for wastewater treatment, bioremediation, and biofuel production. Recently, growing research attention has been devoted to the development of microbial electrochemical sensrs as biosensing platforms. Microbial electrochemical sensors are a type of microbial electrochemical technology (MET) capable of sensing through the anodic or the cathodic electroactive microorganisms and/or biofilms. Herein, we review and summarize the recent advances in the design of microbial electrochemical sensing approaches with a specific overview and discussion of anodic and cathodic microbial electrochemical sensor devices, highlighting both the advantages and disadvantages. Particular emphasis is given on the current trends and strategies in the design of low-cost, convenient, efficient, and high performing METs with different biosensing applications, including toxicity monitoring, pathogen detection, corrosion monitoring, as well as measurements of biological oxygen demand, chemical oxygen demand, and dissolved oxygen. The conclusion provides perspectives and an outlook to understand the shortcomings in the design, development status, and sensing applications of microbial electrochemical platforms. Namely, we discuss key challenges that limit the practical implementation of METs for sensing purposes and deliberate potential solutions, necessary developments, and improvements in the field.     

Tailoring the electrode surface structure by cathodic corrosion in alkali metal hydroxide solution: Nanostructuring and faceting of Au

Nanostructured metals are vital materials in several (electro)chemical applications. Despite the substantial progress in this field, still many limitations are associated with traditional synthetic procedures, including the availability of stable nanoparticles on appropriate supports by avoiding migration and aggregation. On that front, cathodic corrosion has emerged as a powerful technique to tailor the surface structure of metal surfaces on the nanoscale. Cathodic corrosion crucially depends on the electrode potential, the nature and the concentration of cations, as well as the electrode material. Controlling these parameters is essential for applying cathodic corrosion in materials design. In this short review, we discuss the most critical parameters controlling cathodic corrosion and highlight the importance of the nature and the concentration of alkali metal hydroxides in aqueous solution.     

Lithium–sulfur redox: challenges and opportunities

Mechanistic and kinetic insights into the lithium–sulfur (Li–S) redox processes are essential to fundamentally increase the utilization of active material and further realize the practical applications of Li–S batteries. In this article, recent advances of in situ/operando characterizations of Li–S reaction processes and mechanism are presented, revealing the multistep transformations of S species. Interfacial visualization, from the whole interface to nanometer scale, provides specific evidence of sulfur distribution, polysulfide diffusion, and lithium sulfide precipitation. Moreover, the development of efficient electrocatalysts to improve the reaction kinetics are additionally presented and discussed. Although the understanding of the mechanism of the Li–S redox processes has improved in recent times, additional efforts are required for the scale-up production and practical applications of Li–S batteries.     

Recent advances in the synthesis and CF functionalization of gem-difluoroalkenes

The gem-difluoroalkenes and related compounds have gained much attention from the organic synthetic community due to their widespread applications as versatile fluorinated building blocks for the synthesis of pharmaceuticals, agrochemicals and functional materials. In the past two decades, significant progress has been made to the development of efficient methods for the construction of gem-difluoroalkenes and useful reactions involving the cleavage of CF bond in gem-difluoroalkenes. In this Digest review, these advances in the synthesis and reaction chemistry of gem-difluoroalkenes are summarized, with special emphasis placed on novel synthetic applications of them in recent ten years.     

Understanding the Physicoelectrochemical Properties of Carbon Nanotubes: Current State of the Art

Carbon nanotubes receive considerable attention in the area of electrochemistry not only due to their reported structural, mechanical or electronic properties but because they represent the world's smallest electrodes allowing electrochemistry to be performed where other electrode materials cannot penetrate. In this review, we overview recent developments in this area summarizing the fundamental advances in understanding the various factors and parameters that can significantly affect the electrochemical reactivity of carbon nanotubes, which is essential for their continual use and successful implementation in a plethora of areas and applications.     

Self-healing Hydrogels and Underlying Reversible Intermolecular Interactions

Self-healing hydrogels have attracted growing attention over the past decade due to their biomimetic structure, biocompatibility, as well as enhanced lifespan and reliability, thereby have been widely used in various biomedical, electrical and environmental engineering applications. This feature article has reviewed our recent progress in self-healing hydrogels derived from mussel-inspired interactions, multiple hydrogen-bonding functional groups such as 2-ureido-4[1 H]-pyrimidinone(UPy), dynami...     

An updated review of metal–organic framework materials in photo(electro)catalytic applications: From CO2 reduction to wastewater treatments

This review summarizes recent advances in the development of metal–organic framework (MOF) materials, focusing on their photocatalytic and photoelectrocatalytic activities for different applications, such as CO₂ reduction, water splitting, elimination of inorganic contaminants, and degradation of organic pollutants. In each section, the first applications described focus on the photocatalysts developed using MOF materials. Meanwhile, the latest are centered on photoelectrode applications using these materials. The last advances in the synthesis process are discussed in terms of improvement in electron transfer and charge separation, which enhance the activity of the photo (electro)catalysts. Finally, some insights about the upcoming applications of MOF materials are provided.     

Electrochemistry of nanobubbles

Gas bubble formation is a common phenomenon in numerous electrochemical processes, such as water splitting, chloralkaline process, and fuel cells. Many efforts have been made to understand the behaviors of microsized or larger gas bubbles in electrochemical systems in the past few decades. It was not until recent years that the electrochemistry of nanosized gas bubbles (nanobubbles) has begun receiving attention. In this short review, we summarize recent advances in the field of electrochemistry of nanobubbles, ranging from new fundamental understandings of nanobubble behaviors to the development of novel bubble-based applications inspired by the basic research of nanobubble electrochemistry.     

Recent advances in molecular fluorescent probes for organic phosphate biomolecules recognition

Organic phosphate biomolecules (OPBs) are indispensable components of eukaryotes and prokaryotes, such as acting as the fundamental components of cell membranes and important substrates for nucleic acids. They play pivotal roles in various biological processes, such as energy conservation, metabolism, and signal modulation. Due to the difficulty of detection caused by variety OPBs, investigation of their respective physiological effects in organisms has been restrained by the lack of efficient tools. Many small fluorescent probes have been employed for selective detection and monitoring of OPBs in vitro or in vivo due to the advantages of tailored properties, biodegradability and in situ high temporal and spatial resolution imaging. In this review, we summarize the recent advances in fluorescent probes for OPBs, such as nucleotides, NAD(P)H, FAD/FMN and PS. Importantly, we describe their identification mechanisms in detail and discuss the general strategies for these OPBs probe designs, which provide new insights and ideas for the future probe designs.     

Scanning electrochemical microscopy in the 21st century

The fundamentals of and recent advances in scanning electrochemical microscopy (SECM) are described. The focus is on applications of this method to studies of systems and processes of active current interest ranging from nanoelectrochemistry to electron transfer reactions and electrocatalysis to biological imaging.     

Experimental and theoretical studies of acridine orange as corrosion inhibitor for copper protection in acidic media

The corrosion process commonly limits the use of copper in practical applications. The use of corrosion inhibitors is one of the effective methods to reduce the corrosion rate of copper. In this research, the inhibition effect of acridine orange (3,6-bis(dimethylamine)acridine) (AcO) for the protection of copper in 0.5 ?M ?H₂SO₄ solution was studied. For this aim, the change of open circuit potential with exposure time (E_ocp-t), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), anodic and cathodic potentiodynamic polarization measurements (PP) and chronoamperometry (CA) techniques were used. Some quantum chemical parameters (E_HOMO, E_LUMO and dipole moment) were calculated and discussed. The AcO film formed over the copper surface was examined by SEM, EDX, AFM and contact angle measurements. The electrochemical data showed that AcO is an effective corrosion inhibitor even at low concentrations (ranging between 99.1% and %99.4 ?at concentrations from 0.01 ?mM to 1 ?mM). The corrosion rate of copper decreases in the presence of the inhibitor by reducing both anodic and cathodic rates, which is depended on its concentration. This compound behaves as mixed-type corrosion inhibitors with predominantly cathodic type. Its adsorption on the copper surface obeys Langmuir adsorption isotherm. The value of adsorption equilibrium constant (K_ads) and the standard free energy of adsorption were ΔG_ads 1.298 x 10³ ?M^?1 and -27.71 ?kJ/mol in the case of 0.5 ?M ?H₂SO₄ solution containing 1.0 ?mM AcO, which shows the adsorption is high and spontaneous. The adsorbed inhibitor film over the metal increase contact angle of the surface, which suggests the more hydrophobic properties of the surface are increasing coming from the orientation of hydrophobic sites to the electrolyte. The zero charge potential (E_pzc) studies showed that the surface charge of the metal is positive in the corrosive media containing the inhibitor. Quantum chemical calculations showed that the binding of inhibitor molecules to the metal surface takes place through N atoms of the inhibitor.     

SECM基本原理及其在金属腐蚀中的应用

扫描电化学显微镜（SECM）是一种具有较高空间分辨率的化学显微镜,在成像和动力学研究已经广泛应用. 本文简要介绍SECM基本原理,综述2009年以来SECM在腐蚀方面的应用,包括扫描成像和异相转移电子化学活性的研究,并简要介绍了作者课题组在SECM方面的研究工作,展望SECM在腐蚀研究的应用.     

Corrosion behaviour of aluminium in NaOH solutions

The electrode potential and the corrosion rate of aluminium were measured in 0.001–2 M NaOH solutions at 30°C. Up to 0.005 M (pH 11.7) the potential was found to be independent of concentration, whereas the corrosion rate is proportional to the alkali concentration. Hence, the corrosion process is diffusion-controlled. Within the concentration range 0.01–0.5 M (pH 12–13.5), the potential decreases at a gradient of 51 mV pH^?1 and the corrosion rate is almost proportional to the square root of concentration. These results were discussed in the light of the kinetics of the anodic and cathodic reactions. Above 0.5 M, both the potential and corrosion rate increase rapidly with concentration. This was attributed to adsorption of Na⁺ ions, which leads to the formation of active cathodic areas at the expense of the anodic ones.     

An investigation of rare earth chloride mixtures: combinatorial optimisation for AA2024‐t3 corrosion inhibition

Rare earth (lanthanides) cations have demonstrated exceptional activity as cathodic corrosion inhibitors for aluminium alloys (AAs). While Ce is generally regarded as the most active, there have been reports of synergistic interactions between mixtures of rare earths, which show increased inhibitive activity. In this study a combinatorial experimental approach was used to evaluate the corrosion inhibition of four rare earth chlorides (Ce, La, Pr, Nd) singly and as mixtures. The estimation of corrosion currents using both potentiodynamic scans and electrochemical impedance spectroscopy (EIS) provided the quantification of corrosion inhibition. The results were then modelled to determine the best predicted inhibition activity. A partial least squares (PLS) regression indicated that the optimal response directly correlated with the amount of Ce present. From the regression analysis, Ce alone demonstrated the best inhibition activity, with the optimum mixture predicted to contain 100% Ce. The addition of La, Pr or Nd, was not observed to improve the inhibition activity. This study represents one of the first applications of combinatorial design to a fundamental question of corrosion inhibition. Copyright © 2010 John Wiley & Sons, Ltd.     

Nanocellulose-based soft actuators and their applications

Nanocellulose has aroused growing attention in the design and fabrication of multifarious soft actuators thanks to its abundant source, appropriate mechanical properties, and sustainability. In this mini-review, an up-to-date account of recent progresses in nanocellulose-based actuators with homogeneous and heterogeneous structures is provided. The fundamental design concepts and synthesis strategies for nanocellulose-based soft actuators with a wide array of micro-architecture are described. Moreover, their actuation mechanisms, structure–function relationships, and emerging applications in the fields of soft robotics, biomedical science and bioelectronics are highlighted. Finally, a brief conclusion, the current challenges, and future perspectives in the development of nanocellulose-based actuators is presented. This mini-review provides new insights into the fundamental research and the technological application of advanced nanocellulose-based soft actuators.     

Encapsulation,protection, and release of hydrophilic active components: Potential and limitations of colloidal delivery systems

There have been major advances in the development of edible colloidal delivery systems for hydrophobic bioactives in recent years. However, there are still many challenges associated with the development of effective delivery systems for hydrophilic bioactives. This review highlights the major challenges associated with developing colloidal delivery systems for hydrophilic bioactive components that can be utilized in foods, pharmaceuticals, and other products intended for oral ingestion. Special emphasis is given to the fundamental physicochemical phenomena associated with encapsulation, stabilization, and release of these bioactive components, such as solubility, partitioning, barriers, and mass transport processes. Delivery systems suitable for encapsulating hydrophilic bioactive components are then reviewed, including liposomes, multiple emulsions, solid fat particles, multiple emulsions, biopolymer particles, cubosomes, and biologically-derived systems. The advantages and limitations of each of these delivery systems are highlighted. This information should facilitate the rational selection of the most appropriate colloidal delivery systems for particular applications in the food and other industries.     

激光扫描光电化学显微技术及其应用进展

综述了激光扫描光电化学显微技术及其在研究金属氢化膜、半导体电极表面修饰、光电化学腐蚀和光电活性物质电沉积过程的应用。     

Solvent-regulated ordering in block copolymers

Studies of the structural polymorphism exhibited by block copolymers in the presence of selective solvents are relatively recent, but very promising in terms of fundamental understanding and practical applications. Highlighting recent advances, this review progresses from `dry' ordered copolymers to solvated ordered (gel-like) copolymers and lastly to solvated disordered (but locally organized) copolymers. Organic- and aqueous-solvent-based systems are concurrently examined to cross-fertilize polymer and colloid science.     

Poly(4-vinylpyridine-hexadecyl bromide) as corrosion inhibitor for mild steel in acid chloride solution

The influence of the addition of poly(4-vinylpyridine-hexadecyl bromide) P4VP-Alkyl 50?% newly synthesized on the corrosion of mild steel in molar hydrochloric acid has been investigated by weight-loss measurements combined with linear potential scan voltammetry (I?CE) and electrochemical impedance spectroscopy (EIS). The polymer reduces the corrosion rate and the inhibition efficiency (E?%) of P4VP-Alkyl 50?% increases with its concentration and attains 95?% at 300?mg/L. E?% obtained from cathodic Tafel plots, EIS, and gravimetric methods were in good agreement. The inhibitor was adsorbed on the iron surface according to the Langmuir adsorption isotherm model. Polarization measurements also show that the compound acts as a cathodic inhibitor.