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Scanning electrochemical microscopy (SECM) is a scanning probe technique capable of imaging substrate topography and measuring the local electrochemical reactivity of interfaces. Since introduced by Allen J. Bard and co-workers in 1989, it has expanded into a wide variety of fields, such as nanomaterial characterization, energy, kinetics, electrocatalysis, metal anti-corrosion, biology and instrumental development. SECM uses an ultra-microelectrode as the probe to record redox current during probe scanning across sample surfaces to obtain local topography and electrochemical reactivity of samples. Specifically, three main topics are reviewed and discussed: (1) the working principles and operating modes of SECM; (2) the recent developments in the application of SECM in energy science, including solar cell, rechargeable batteries, fuel cells and supercapacitors, with an emphasis on the last five years (2019–2023); (3) the perspectives and outlook of SECM in various energy devices. We anticipate that a wider adoption of SECM by the energy community will allow for the operando characterization of many types of reactions, and hold the potential to provide new insights into the structure/activity and composition/activity relationships. [ABSTRACT FROM AUTHOR]

Graphene microband electrodes were fabricated by direct laser writing on Kapton® polyimide tape utilizing a low-cost, blue laser (500 mW and 405 nm). The structural properties of the graphene were examined by Raman spectroscopy, and key features such as D, G, and 2D bands and the presence of multilayer structures were revealed. Scanning electron microscopy (SEM) provided insights into the microband morphology, highlighting the 3D (foam-like) nature of the graphene microbands. Electrochemical experiments revealed cyclic voltammetry profiles that demonstrated radial diffusion dominance at low scan rates and Randles–Sevcik behavior at higher scan rates. Reproducibility and repeatability analyses confirmed the stability and consistency of these microband electrodes within individual devices. Scanning electrochemical microscopy (SECM) images revealed the electrochemical reactivity of the microbands. At a relatively low microband separation (200 µm), the produced material can be collected at the adjacent microband, which was confirmed via generator/collector experiments. Theoretical–experimental comparisons regarding the current measured for a single microband were performed, and the obtained results were in good agreement, with deviations attributed to the 3D morphology of the microbands. This research underscores the potential of these cost-effective and reproducible graphene microband electrodes for diverse applications in electrochemical sensing, and we present preliminary results on caffeic acid and paracetamol detection. [ABSTRACT FROM AUTHOR]

The study employs a multimicroscopy approach, combining Scanning Electrochemical Cell Microscopy (SECCM) and Field Emission Scanning Electron Microscopy (FESEM), to investigate electrochemical nucleation and growth (EN&G). Cu nanoparticles (NPs) are meticulously electrodeposited on glassy carbon (GC), to perform co‐located characterization, supported by analytical modeling and statistical analysis. The findings reveal clear correlations between electrochemical descriptors (i–t transients) and physical descriptors (NPs size and distribution), offering valuable insights into nucleation kinetics, influenced by varied overpotentials, surface state, and electrode's area. Analysis of the stochasticity of nucleation reveals intriguing temporal distributions, indicating an increased likelihood of nucleation with higher overpotential and larger electrode's area. Notably, the local surface state significantly influences nucleation site number and activity, leading to spatial differences in nucleation rates unaccounted for in macroscopic experiments. The updated analytical model for EN&G current transients, considering SECCM geometry, shows excellent agreement with FESEM measurements, facilitating the calculation of active sites within individual regions. These results deepen the understanding of EN&G phenomena from a new perspective, and lay the groundwork for further theoretical advancements, showcasing the great potential of current experimental methods in advancing precise electrochemical manufacturing of micro‐ and nanostructures. [ABSTRACT FROM AUTHOR]

The document is a contents list from the journal "Analyst" published by The Royal Society of Chemistry, featuring various research papers on topics such as metal surface interactions, cerumen analysis, nano-biosensing platforms, and Raman spectroscopy for leukemia diagnosis. The journal showcases innovative research in the field of chemistry, including advancements in spectroscopy techniques, biosensing platforms, and diagnostic tools. The articles cover a wide range of topics, from nanotechnology to bioanalytical assays, highlighting the diverse and cutting-edge research being conducted in the chemical sciences. [Extracted from the article]

The commercialization of zinc metal batteries (ZMBs) for large‐scale energy storage is hindered by challenges such as dendrite formation, the hydrogen evolution reaction (HER), and passivation/corrosion, which lead to poor stability of zinc metal anodes. HER is a primary contributor to this instability, and despite efforts to enhance ZMB cyclability, a significant knowledge gap remains regarding the origin of HER in these systems. Prior works, based primarily on theoretical calculations with minimal experimental support, suggest that HER originates from Zn2⁺‐solvated water. For the first time, by employing scanning electrochemical microscopy (SECM), and electrochemical mass spectrometry (ECMS), in real‐time the inherently intertwined nature of Zn electrodeposition and H₂ liberation is revealed, both exhibiting the same onset potential in voltammetry. The findings show that water molecules surrounding Zn2⁺ ions undergo reduction simultaneously during Zn2⁺ deposition. Additionally, ECMS conducted under chronopotentiometric/galvanostatic conditions at battery‐relevant current densities elucidates why elevated electrolyte concentrations enhance the prolonged cyclability of ZMBs. Understanding the origin of HER opens avenues for developing high‐performance, reliable aqueous ZMBs, addressing key challenges in their commercialization and advancing their technological capabilities. [ABSTRACT FROM AUTHOR]

MXene, a family of 2D transition metal carbides and nitrides, presents promising applications in electrocatalysis. Maximizing its large surface area is key to developing efficient non‐noble‐metal catalysts for the hydrogen evolution reaction (HER). In this study, oxygen‐functionalized Ti3C2Tx MXene (Ti3C2Ox) is synthesized and deposited gold nanoparticles (Au NPs) onto it, forming a novel composite material, Au‐Ti3C2Ox. By selectively removing other functional groups, mainly ‐O functional groups are retained on the surface, directing electron transfer from Au NPs to MXene due to electronic metal‐support interaction (EMSI), thereby improving the catalytic activity of the MXene surface. Additionally, the interaction between Au NPs and ‐O functional groups further enhanced the overall catalytic activity, achieving an overpotential of 62 mV and a Tafel slope of 40.1 mV dec−1 at a current density of −10 mA cm−2 in 0.5 m H2SO4 solution. Density functional theory calculations and scanning electrochemical microscopy with ≤150 nm resolution confirmed the enhanced catalytic efficiency due to the specific interaction between Au NPs and Ti3C2Ox. This work provides a surface modification strategy to fully utilize the MXene surface and enhance the overall catalytic activity of MXene‐based catalysts. [ABSTRACT FROM AUTHOR]

The fabrication of hydroxyapatite (HAP)/MgO composite coatings on Mg alloy is crucial for enhancing the corrosion resistance and biocompatibility of biomedical implants. In this study, we aimed to investigate the effects of two different surface modification methods, i.e., electrochemical (electrodeposition, ED) and chemical (solution treatment, ST), on the phase structure, degradation properties, and biocompatibility of the composite coatings in comparison to the anodized coating. The surface morphologies and crystalline structures of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Subsequently, the degradation rate of the coatings in simulated body fluid were comprehensively evaluated by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electrochemical microscopy (SECM) tests. Additionally, in-vitro cell proliferation assays were employed to quantitatively assess the biocompatibilities of the coatings. The results showed that both ED and ST methods were effective in depositing HAP on anodized Mg alloy, resulting in different surface morphologies with hydroxyapatite layer thicknesses of 2.71 μm and 3.56 μm, respectively. In this way, the HAP-deposited coatings exhibited improved corrosion resistances and biocompatibilities compared with those of the anodized coating. Specifically, the ST-deposited composite film displayed superior degradability and biocompatibility which was attributed to its filiform surface morphology and thicker HAP layer. Overall, the present study demonstrates the potential of HAP/MgO composite coatings for biomedical applications, with implications for the development of advanced implant materials with improved performance and biocompatibility. [ABSTRACT FROM AUTHOR]

Passive films are essential for the longevity of metals and alloys in corrosive environments. A great deal of research has been devoted to understanding and characterizing passive films, including their chemical composition, uniformity, thickness, porosity, and conductivity. Many characterization techniques are conducted under vacuum, which do not portray the true in‐service environments passive films will endure. Scanning electrochemical probe microscopy (SEPM) techniques have emerged as necessary tools to complement research on characterizing passive films to enable the in situ extraction of passive film parameters and monitoring of local breakdown events of compromised films. Herein, we review the current research efforts using scanning electrochemical microscopy, scanning electrochemical cell microscopy (or droplet cell measurements), and local electrochemical impedance spectroscopy techniques to advance the knowledge of local properties of passivated metals. The future use of SEPM for quantitative extraction of local film characteristics within in‐service environments (i.e., with varying pH, solution composition, and applied potential) is promising, which can be correlated to nanostructural and microstructural features of the passive film and underlying metal using complementary microscopy and spectroscopy methods. The outlook on this topic is highlighted, including exciting avenues and challenges of these methods in characterizing advanced alloy systems and protective surface films. [ABSTRACT FROM AUTHOR]

Most research on the corrosive CoCrFeNi high-entropy alloy (HEA) has mainly modulated element species and atomic concentration recently. However, the corrosive resistance of the passive film in the elevated temperatures environment inevitably need to be extensively explored for application. In this work, the microstructure and corrosion behavior in the elevated temperatures of face-centered cubic (FCC) CoCrFeNiWx (x = 0 and 0.2) HEAs are investigated. The mechanism of passivation layers on the corrosion behavior of HEAs is further discussed for comparison to the alloy of addition tungsten. Through potentiodynamic polarization curves in 3.5 wt% NaCl solution from 25 °C to 70 °C, the addition of tungsten can raise the critical pitting temperature, while maintaining a lower passivation current density and a larger passivation range at the same time. The high resolution X-ray photoelectron spectrometer (HRXPS), electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) are all conducted to analyze the passivation composition and chemical reaction of the present alloys detailly. The CoCrFeNiW0.2 HEA exhibits the uniform Cr2O3 layer on the FCC matrix; the proportion of dispersive WO3 layer on the μ phase precipitates form a double-layer passive film under elevated temperature in 3.5 wt% NaCl. It shows that the synergistic effect of the double-layer passive film significantly enhances the pitting and corrosive resistance in this HEA.

Room temperature ionic liquids (RT-ILs) are promising electrolytes for electrocatalysis. Understanding the effects of the electrode–electrolyte interface structure on electrocatalysis in RT-ILs is important. Ultrafast mass transport of redox species in N-methyl-N-ethyl-pyrrolidinium polybromide (MEPBr2n+1) enabled evaluation of the reorganization energy (λ), which reflects the solvation structure in the inner Helmholtz plane (IHP). λ was achieved by fitting the electron transfer rate-limited voltammogram at a Pt ultramicroelectrode (UME) to the Marcus–Hush–Chidsey model for heterogeneous electron transfer kinetics. However, it is time-consuming or even impossible to prepare electrode materials, including alloys of numerous compositions in the form of UME, for each experiment. Herein, we report a method to evaluate the λ of MEPBr2n+1 by scanning electrochemical cell microscopy (SECCM), which allows high throughput electrochemical measurements using a single electrode with high spatial resolution. Fast mass transport in the nanosized SECCM tip is critical for achieving heterogeneous electron transfer-limited voltammograms. Furthermore, investigating λ on a high-entropy alloy materials library composed of Pt, Pd, Ru, Ir, and Ag suggests a negative correlation between λ and the work function. Given that the potential of zero charge correlates with the work function of electrodes, this can be attributed to the surface-charge sensitive ionic structure in the IHP of MEPBr2n+1, modulating the solvation energy of the redox-active species in the IHP. [ABSTRACT FROM AUTHOR]

Understanding the interaction between cyclic stresses and corrosion of magnesium (Mg) and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials. This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials, with an emphasis on microscale processes, and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques. The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects (grain size, precipitates, deformation twins), as well as the formation of pits. Furthermore, in the case of coated alloys, the role of coating defects in these phenomena is also described. In this context, the feasibility of using scanning electrochemical microscopy (SECM), scanning vibrating electrode technique (SVET), scanning ion-selective electrode technique (SIET), localized electrochemical impedance spectroscopy (LEIS) and scanning Kelvin probe (SKP) methods to study the corrosion-fatigue interaction of Mg alloys is examined. A comprehensive review of the current literature in this field is presented, and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed.

Finding strategies to enhance catalysts' electrochemical activity is based on controlling the material design. Bidimensional materials (2DM) such as MoS2 are explored as catalysts for the hydrogen evolution reaction (HER). A comprehensive study of the effects of doping 2D materials with transition metals based on theoretical predictions in tandem with experimental investigation correlates the doping type to the changes in the electronic and electrochemical activity. Localized electrochemical maps obtained by scanning electrochemical cell microscopy (SECCM) reveal that Ti‐doping induces a heterogeneous increase in 2H‐MoS2 basal plane electrochemical activity, while Ni‐doping induces a homogeneous decrease. Additionally, Kelvin probe microscopy provides insight into Ti‐doping, showcasing a decline in the 2H‐MoS2 work function, therefore confirming the predictions from density functional theory simulations. In essence, the findings underscore the potential of transition metal coordination on the 2H‐MoS2 surface as an attractive method for locally doping 2D materials with minimal damage to the crystalline lattice, consequently enhancing the electrochemical activity on the material's basal plane. [ABSTRACT FROM AUTHOR]

The influence of the ion transfer on photoinduced electron transfer (ET) reactions was studied on the surface of hyperbranched semiconducting BiVO4 particles spontaneously adsorbed at the liquid‐liquid (L/L) interface between an aqueous LiCl solution and bis(triphenylphosphoranylidene) ammonium tetrakis(pentaflurophenyl)borate (BATB) in 1,2‐dichlorethane. The organic electrolyte was supplemented with [Co(bpy)3](PF6)3 to accept photoexcited electrons from BiVO4 under formation of the corresponding Co(II) complex. The L/L interface was stabilized at the orifice of a micropipette (MP) and allowed to record ion transfer cyclic voltammetry (ITCV) by applying a Galvani potential difference Δowϕ ${{\rm{\Delta }}_o^w \varphi }$ between two reference electrodes in the electrolyte solutions with intermittent illumination by visible light (λ>420 nm). The photogenerated holes caused oxidation of water to O2. Co(II) and O2 were detected at constant Δowϕ ${{\rm{\Delta }}_o^w \varphi }$ at an amperometric microelectrode (ME) facing the orifice of the MP in either the organic or the aqueous electrolyte. The overall current exhibits a photocurrent only in the Δowϕ ${{\rm{\Delta }}_o^w \varphi }$ ‐range, in which the IT of PF6− is kinetically limited. The amperometric detection of photogenerated products followed the same pattern as the photocurrent in the total current. [ABSTRACT FROM AUTHOR]

For the anodic H2O2 generation, it has been shown that the electrolyte composition can steer the reaction pathway toward increased H2O2 generation. Previous efforts made on composition optimization found that the impact of the molar fraction of carbonate species varies for different anodes, and therefore, controversies remain concerning the reaction pathways as well as the species involved in H2O2 formation. Considering that water oxidation results in the liberation of protons within the anode microenvironment, the corresponding acidification would cause an equilibrium shift between carbonate species, which in turn may modulate the reaction pathway. We determined the changes in the fraction of carbonate species in the vicinity of an anode by performing local pH measurements using a Au nanoelectrode positioned in close proximity to an operating anode by shear‐force scanning electrochemical microscopy (SECM). It could be confirmed that the main anionic species at the interface is HCO3−, at potentials where H2O2 is preferentially formed, regardless of the pH value in the bulk. The simultaneous use of a Au−Pt double barrel microelectrode in generator‐collector SECM measurements demonstrates that the local HCO3− concentration is collectively determined by the oxidation current, buffer capacity, and bulk pH of the electrolyte. [ABSTRACT FROM AUTHOR]

We present a molecular‐scale investigation of the axial coordination effect of atomic iodine on Fe‐N4 sites in the oxygen reduction reaction (ORR) by electrochemical scanning tunneling microscopy (ECSTM). A well‐defined model catalytic system with explicit and uniform iodine‐coordinated Fe‐N4 sites was constructed facilely by the self‐assembly of iron(II) phthalocyanine (FePc) on an I‐modified Au(111) surface. The electrocatalytic activity of FePc for the ORR shows notable enhancement with axial iodine ligands. The modulation of the electronic structure of Fe sites to evoke a higher spin configuration by axial iodine was evidenced. The interaction strength between oxygen‐containing species and active centers becomes weaker due to the presence of iodine ligands, and the reaction is thermodynamically preferable. Furthermore, the reaction dynamics of FePc on I/Au(111) were explicitly determined via in situ ECSTM potential pulse experiments. In contrast, axial atomic iodine was found inefficacious for improving the activity of Co‐N4 sites, and electron rearrangement was found to be marginal, demonstrating that adequate interactions between axial ligands and metal sites for optimizing electronic structures and catalytic behaviors are prerequisites for the impactful role of axial ligands. [ABSTRACT FROM AUTHOR]

The meniscus-confined electrodeposition (MCED) technique offers advantages such as low cost and wide applicability, making it a promising method in the field of micro/nanofabrication. However, unstable meniscal morphology and poor deposition quality during planar deposition in MCED necessitate the development of improved methods. Therefore, a planar adaptive micro-tuning deposition method (PAMTDM), which utilizes the positioning technology of scanning electrochemical cell microscopy (SECCM) and employs a singular value decomposition (SVD) planar fitting method to determine the flatness of the deposition plane, is proposed. An adaptive micro-tuning motion mode was proposed by analyzing the variation patterns of the meniscus. Moreover, a combination of multi-physics finite element simulations and orthogonal experimental methods was introduced to determine the optimal motion parameters. The experimental results demonstrate that the PAMTDM effectively addresses the issues encountered during planar growth. Compared to the point-by-point deposition method, the PAMTDM achieves a threefold increase in deposition speed for continuous deposition of 105-μm-long line segments in two-dimensional planes, with a deposition current error of less than 0.2 nA. In conclusion, the proposed method provides significant insights into the broad future applications of MCED. [ABSTRACT FROM AUTHOR]

The vast number of element combinations and the explosive growth of composition space pose significant challenges to the development of high‐entropy alloys (HEAs). Here, we propose a procedural research method aimed at accelerating the discovery of efficient electrocatalysts for oxygen reduction reaction (ORR) based on Pt‐based quinary HEAs. The method begins with an element library provided by a large language model (LLM), combined with microscale precursor printing and pulse high‐temperature synthesis techniques to prepare multi‐element combination HEA array in one step. Through high‐throughput measurement using scanning electrochemical cell microscopy (SECCM), precise identification of highly active HEA element combinations and exploration of composition space for a specific combination are achieved. Advantageous element combinations are further validated in practical electrocatalytic evaluations. The contributions of individual element sites and the synergistic effects among elements of such HEAs in enhancing reaction activity are elucidated via density functional theory (DFT) calculations. This method integrates high‐throughput experiments, practical catalyst validation, and DFT calculations, providing a new pathway for accelerating the discovery of efficient multi‐element materials in the field of energy catalysis. [ABSTRACT FROM AUTHOR]

Redox processes in the polymer film of poly-N,N′-ethylenebis(3-methoxysalicylideneimine were studied for the first time by in situ methods including electron spin resonance spectroscopy, ultraviolet—visible—near-infrared spectroscopy, and Fourier transform infrared spectroscopy. The integration of the obtained data with the results of electrochemical nanomechanical atomic force microscopy measurements allowed us to determine causes of a low electrochemical oxidative polymerization efficiency of this compound and a rapid loss of its electrochemical activity in the oxidation—reduction processes. [ABSTRACT FROM AUTHOR]

In scanning electrochemical microscopy (SECM), the addition of a redox active species plays an essential role. Those deliberately added mediators may alter results in SECM studies. In investigations of lithium‐ion battery (LIB) materials, especially of the positive electrode, the oxidation potentials of commonly used mediator substances such as ferrocene are located within the operation potential of the electrode. Thus, they possibly interfere with the regular charge/discharge processes. In situ studies are therefore in need of approaches reducing or eliminating the use of mediators. Within this publication, a novel mediator dosing (MD) concept is introduced. A capillary was closely positioned at the tip of the scanning probe. By gravity flow, stable flow rates of mediator solution of up to 32.4±0.6 μL h−1 were achieved. These low amounts were found to be sufficient to form a ferrocene zone at the probe tip enabling feedback mode SECM measurements with comparable quality to measurements directly in ferrocene solution. Proof of concept experiments were conducted by investigation of a thin‐film electrode with a micro‐structured surface. Furthermore, the MD concept was applied in imaging experiments of a commercially available LIB graphite electrode. [ABSTRACT FROM AUTHOR]

Correlative methods to characterize single entities by electrochemistry and microscopy/spectroscopy are increasingly needed to elucidate structure‐function relationships of nanomaterials. However, the technical constraints often differ depending on the characterization techniques to be applied in combination. One of the cornerstones of correlative single‐entity electrochemistry (SEE) is the substrate, which needs to achieve a high conductivity, low roughness, and electrochemical inertness. This work shows that graphitized sputtered carbon thin films constitute excellent electrodes for SEE while enabling characterization with scanning probe, optical, electron, and X‐ray microscopies. Three different correlative SEE experiments using nanoparticles, nanocubes, and 2D Ti3C2Tx MXene materials are reported to illustrate the potential of using carbon thin film substrates for SEE characterization. The advantages and unique capabilities of SEE correlative strategies are further demonstrated by showing that electrochemically oxidized Ti3C2Tx MXene display changes in chemical bonding and electrolyte ion distribution. [ABSTRACT FROM AUTHOR]

There is a need for high-throughput, scale-relevant, and direct electrochemical analysis to understand the corrosion behavior and sensitivity of nuclear materials that are exposed to extreme (high pressure, temperature, and radiation exposure) environments. We demonstrate the multi-scale, multi-modal application of scanning electrochemical cell microscopy (SECCM) to electrochemically profile corrosion alterations in nuclear alloys in a microstructurally resolved manner. Particularly, we identify that both mechanically deformed and irradiated microstructures show reduced charge-transfer resistance that leads to accelerated oxidation. We highlight that the effects of mechanical deformation and irradiation are synergistic, and may in fact, superimpose each other, with implications including general-, galvanic-, and/or irradiation-activated stress-corrosion cracking. Taken together, we highlight the ability of non-destructive, electrochemical interrogations to ascertain how microstructural alterations result in changes in the corrosion tendency of a nuclear alloy: knowledge which has implications to rank, qualify and examine alloys for use in nuclear construction applications. [ABSTRACT FROM AUTHOR]

To study the influence of different cleaning methods on the corrosion resistance of 316L stainless steel surface, this paper carried out polarisation curves and electrochemical impedance spectroscopy studied on the uncleaned, acid pickling cleaning, and picosecond laser cleaning samples. The surface morphology of the samples after electrochemical testing was detected by laser confocal microscopy and scanning electron microscopy, and then the electrochemical corrosion behaviour of the samples in 3.5% NaCl solution was analysed under different cleaning methods. The results show that compared with the uncleaned sample, the corrosion potential of the sample after picosecond laser cleaning was relatively improved. At this time, the corrosion current density was as low as 2.29 × 10–6 A/cm2, the polarisation resistance value was as high as 18615 Ω·cm2, the impedance modulus was as high as 5.5 × 105 Ω, and the capacitance-impedance radius reached the maximum value. In conclusion, the corrosion resistance of the sample after picosecond laser cleaning was better. [ABSTRACT FROM AUTHOR]

• Interaction between corrosion and fatigue of magnesium alloy at microscale level. • Application of scanning electrochemical techniques in these processes. • Interaction of microstructures with local corrosion/ fatigue processes. Understanding the interaction between cyclic stresses and corrosion of magnesium (Mg) and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials. This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials, with an emphasis on microscale processes, and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques. The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects (grain size, precipitates, deformation twins), as well as the formation of pits. Furthermore, in the case of coated alloys, the role of coating defects in these phenomena is also described. In this context, the feasibility of using scanning electrochemical microscopy (SECM), scanning vibrating electrode technique (SVET), scanning ion-selective electrode technique (SIET), localized electrochemical impedance spectroscopy (LEIS) and scanning Kelvin probe (SKP) methods to study the corrosion-fatigue interaction of Mg alloys is examined. A comprehensive review of the current literature in this field is presented, and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing highly efficient and cost‐effective electrocatalysts for oxygen reduction reaction (ORR) in aqueous media is crucial for energy conversion systems such as fuel cells or Zn‐air batteries. Electrode materials from spent devices such as lithium‐ion batteries (LiBs) are a serious environmental problem. One of the solutions is their reuse for other electrochemical processes. This work demonstrates the application of solid residues of carbon‐based powders left over from the hydrometallurgical recycling process of LIBs' waste as efficient catalysts for ORR. Microscopic and spectroscopic studies of the residue disclosed their porous structure and various cobalt contents, depending on the recycling procedure. These battery wastes display ORR catalytic activity when deposited at the liquid‐liquid and solid electrode‐electrolyte interfaces. Scanning Electrochemical Microscopy (SECM) tests showed that assembling battery waste at the liquid‐liquid interface boosts the efficiency of H2O2 production by one to two orders of magnitude. The catalytic activity towards 2‐electron ORR strongly depends on waste powder compositions and structures, e.g., porosity, heteroatom presence, level of defects, and graphitization. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence (ECL) is rapidly evolving from an analytical method into an optical microscopy. The orthogonality of the electrochemical trigger and the optical readout distinguishes it from classic microscopy and electrochemical techniques, owing to its near‐zero background, remarkable sensitivity, and absence of photobleaching and phototoxicity. In this minireview, we summarize the recent advances in ECL imaging technology, emphasizing original configurations which enable the imaging of biological entities and the improvement of the analytical properties by increasing the complexity and multiplexing of bioassays. Additionally, mapping the (electro)chemical reactivity in space provides valuable information on nanomaterials and facilitates deciphering ECL mechanisms for improving their performances in diagnostics and (electro)catalysis. Finally, we highlight the recent achievements in imaging at the ultimate limits of single molecules, single photons or single chemical reactions, and the current challenges to translate the ECL imaging advances to other fields such as material science, catalysis and biology. [ABSTRACT FROM AUTHOR]

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High‐entropy alloys (HEAs), especially in the form of compositional complex solid solutions (CCSS), have gained attention in the field of electrocatalysis. However, exploring their vast composition space concerning their electrocatalytic properties imposes significant challenges. Scanning electrochemical cell microscopy (SECCM) offers high‐speed electrochemical analysis on surface areas with a lateral resolution down to tens of nm. However, high‐precision piezo positioners often used for the motion of the tip limit the area of SECCM scans to the motion range of the piezo positioners which is typically a few tens of microns. To bridge this experimental gap, the study proposes a long‐range SECCM system with a rapid gas‐exchange environmental cell for high‐throughput electrochemical characterization of 100 mm diameter HEA thin‐film material libraries (ML) obtained by combinatorial co‐sputtering. Due to the gas–liquid interface at the positioned SECCM droplet on the sample, high‐throughput evaluation under industrial current density conditions becomes feasible. This allows the direct correlation between electrocatalytic activity and material composition with high statistical reliability. The multidimensional data obtained accelerates materials discovery, development, and optimization. [ABSTRACT FROM AUTHOR]

Electroanalysis is a type of analytical method used to study an analyte by measuring its electrical properties in an electrochemical cell. It has been widely used because it is a relatively simple and inexpensive technique, has a low detection limit and is able to measure original electrical signals. Electroanalysis has advanced with the development of nanotechnology, offering new opportunities for analysis. Scanning electrochemical microscopy (SECM) is a probe-based surface analysis instrument that enables real-time surface and interfacial analysis with spatial resolution in an electrochemical environment. In this review, we focus on the use of nanoscale SECM for improved electroanalysis. After introducing the fabrication, characterization, and modification of nanoelectrodes, which are the key to enabling nanoscale SECM, we introduce the instrumentation and fundamental principles of SECM. Several examples are provided to illustrate the advanced electroanalysis of photo-electrocatalysts and biosystems based on nanoscale SECM, which will be utilized as a more powerful electroanalytical tool in the future when combined with other analytical instruments.

A method is presented to quantitatively analyze the reduction of vanadium(V) to vanadium(IV) over two flat carbon substrates (glassy carbon and graphite foil) using the feedback mode of scanning electrochemical microscopy. A pulse profile is validated and applied during approach curve experiments of a 10 μm Pt microelectrode. By fitting the approach curve data, electron transfer constants are calculated for various potentials and k0 is extracted from the corresponding Tafel plot. Furthermore, surface functional groups were introduced to the carbon substrates by acid treatment; however, kinetic parameters of the sluggish reduction reaction were only influenced to a minor extent. Finally, the same approach, combined with in situ‐Raman microscopy, is applied to a single graphene layer using a 2.7 μm Pt microelectrode. In this case, increased activity for both, the vanadium(V) reduction and vanadium(IV) oxidation reaction, was found close to the graphene edge sites by means of electrochemical microscopy for the first time. [ABSTRACT FROM AUTHOR]

Scanning electrochemical microscopy (SECM) has emerged as a powerful method to quantitatively investigate the transport of molecules and ions across various biological membranes as represented by living cells. Advantageously, SECM allows for the in situ and non-destructive imaging and measurement of high membrane permeability under simple steady-state conditions, thereby facilitating quantitative data analysis. The SECM method, however, has not provided any information about the interactions of a transported species, i.e., a permeant, with a membrane through its components, e.g., lipids, channels, and carriers. Herein, we propose theoretically that SECM enables the quantitative investigation of membrane-permeant interactions by employing transient conditions. Specifically, we model the membrane-permeant interactions based on a Langmuir-type isotherm to define the strength and kinetics of the interactions as well as the concentration of interaction sites. Finite element simulation predicts that each of the three parameters uniquely affects the chronoamperometric current response of an SECM tip to a permeant. Significantly, this prediction implies that all three parameters are determinable from an experimental chronoamperometric response of the SECM tip. Complimentarily, the steady-state current response of the SECM tip yields the overall membrane permeability based on the combination of the three parameters. Interestingly, our simulation also reveals the optimum strength of membrane-permeant interactions to maximize the transient flux of the permeant from the membrane to the tip. [ABSTRACT FROM AUTHOR]

We have fabricated multifunctional conductive fabrics composed of polypyrrole/BaTiO3/poly(acrylonitrile‐co‐methylacrylate) (PPy/BaTiO3/P(AN‐co‐MA)(PBA) utilizing a simple process including dip coating and in situ chemical polymerization of pyrrole, which oxidized both ammonium persulfate (APS) and ammonium persulfate + iron (III) chloride (APS + FeCl3) for flexible and wearable textile applications. The influence of the oxidant nature, PPy content, and BaTiO3 on the surface structures, electrochemical, and semiconducting characteristics of the fabrics was examined using scanning electrochemical microscopy (SEM), electrochemical impedance spectroscopy (EIS), and the Mott–Schottky (M–S) studies. The study revealed that the size of the polymer nanostructures on fabric has an impact on the electrochemical impedance properties. Specifically, a decrease in diameter (when FeCl3 + APS is used) or the formation of more compact swelling surface structures (when only APS is used) is associated with changes in the conductivity of the coated fabric. Based on the EIS tests, the composite coating (S0.1, S0.2, and S0.3) with FeCl3 has a higher electrical conductivity compared to the coating with APS (PBA). The M–S tests indicate that the semiconducting characteristics of coated fabrics are dependent upon the kind of oxidant, the amount of PPy, and the presence of BaTiO3. [ABSTRACT FROM AUTHOR]

In the present study, the fabrication route, including combining the aerosol deposition method and magnetron sputtering, was demonstrated for the fabrication of metal-supported solid oxide fuel cells. Thick-film anode layers (approximately 45 µm) of 10 mol.% gadolinia-doped ceria (GDC) and nickel (57/43 wt% ratio) were deposited by means of the aerosol deposition method on porous metal (Cr-28 wt%, Fe) supports from softly agglomerated submicron powders. The half-cells with the anode layers were sintered at 1000 °C in vacuum. Thin-film membranes of gadolinia-doped ceria (approximately 4 µm) were deposited by magnetron sputtering. (La0.80Sr0.20)0.95CoO3−δ (LSC) cathode layers were applied by screen printing with subsequent in situ sintering. The manufactured cells were investigated by scanning electron microscopy and electrochemical measurements. Depending on the manufacturing route and testing temperature, the cells with hydrogen as a fuel and air as an oxidant demonstrated open circuit voltages from 0.57 to 0.82 V. At 750 °C, the cell maximum power density was 0.3 W cm−2. [ABSTRACT FROM AUTHOR]

The adsorption of a conductive mineral toward a collector changes its interface electrochemical property, implying the hydrophobization mechanism of froth flotation. Herein, the interface electrical behavior of chalcopyrite was investigated by in situ scanning electrochemical microscopy (SECM). And the results demonstrated that the treatment of N, N-diethyl-S-[2-amino-2-(hydroxyimino) ethyl] dithiocarbamate ester (DEAHEDTC) significantly reduced the tip feedback current i and heterogenous electron transfer rate constant k of chalcopyrite interface, implying the self-assembly of DEAHEDTC on chalcopyrite surface. The adsorption mechanism investigations further revealed that both DEAHEDTC's C(=NOH)-NH2 and N-C(=S) groups combined with the surface Cu atom(s) of chalcopyrite, leaving its hydrophobic groups outward against chalcopyrite. For the hydrophobic groups that are non-conducting, the electrochemical activity of chalcopyrite interface decreased. While the hydrophobization of DEAHEDTC returned a high flotation recovery of chalcopyrite particles. [ABSTRACT FROM AUTHOR]

Constructing low‐tortuosity structure is a facile and effective strategy to significantly improve the electrochemical performances of thick electrodes of batteries. In this study, the low‐tortuosity structured electrodes with an array grooved structure are fabricated using a method of laser etching post‐processing, promoting excellent electrochemical performance of sodium‐ion batteries (SIBs). The effects of laser post‐processing parameters including the etching shape, interval, and scan number on the structures and electrochemical performances of the prepared electrodes are investigated. Results show that the array grooved structures of the laser‐treated electrodes not only reduce the tortuosity to enhance the ion transfer efficiency, but also provide extra space to accommodate more electrolyte, which helps strengthen the electrochemical reaction kinetics of the electrodes. The proposed electrode with a parallelogram etching shape, an interval of 0.1 mm, and a scan number of 10 can produce a high rate capacity of 120.7 mAh g−1 at 500 mA g−1 and an outstanding cycle performance with a high capacity maintenance rate of 97.8% after 200 cycles. This study validates a new method to create low‐tortuosity electrodes for SIBs by optimizing the process parameter, which can be potentially extended to the fabrication of other advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Mg-rare earth (RE) alloy, i.e., Mg-1Zn-1Gd (ZG11), was treated by a conventional pulse anodization process. The effect of electrical parameters (processing time, duty cycle and applied current) on the microstructure and corrosion resistance of anodized film was investigated by orthogonal method. SEM and XRD were used to characterize the microstructures and compositions of anodized films. Polarization curve, electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) were performed to evaluate the corrosion resistances of anodized samples. The results show that with the employment of appropriate electrical parameters, corrosion resistance of ZG11 alloy can be significantly enhanced (icorr decreases by nearly three orders of magnitude) after anodized for less than 2 min. Besides, the optimal sample selected from orthogonal experiments in terms of the thickness and porosity of anodized film appropriately matches with the sample with the best corrosion resistance determined by electrochemical corrosion measurements, indicating the strong relationship between the thickness and porosity of anodized film and its corrosion resistance. Additionally, results of cell proliferation tests demonstrate that the varied surface morphologies and microstructure characteristics of the anodized samples in the present study do not necessarily influence the related cytocompatibilities. The study helps to further understand the effect orders of different current parameters on the structure and properties of anodized film and therefore provides a high-efficiency and low-energy consumption way to manufacture Mg alloys with excellent corrosion resistances. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations demonstrate neighboring Pt atoms can enhance the metal activity of NiCoP for hydrogen evolution reaction (HER). However, it remains a great challenge to link Pt and NiCoP. Herein, we introduced curvature of bowl‐like structure to construct Pt/NiCoP interface by adding a minimal 1 ‰‐molar‐ratio Pt. The as‐prepared sample only requires an overpotential of 26.5 and 181.6 mV to accordingly achieve the current density of 10 and 500 mA cm−2 in 1 M KOH. The water dissociation energy barrier (Ea) has a ~43 % decrease compared with NiCoP counterpart. It also shows an ultrahigh stability with a small degradation rate of 10.6 μV h−1 at harsh conditions (500 mA cm−2 and 50 °C) after 3000 hrs. X‐ray photoelectron spectroscopy (XPS), soft X‐ray absorption spectroscopy (sXAS), and X‐ray absorption fine structure (XAFS) verify the interface electron transfer lowers the valence state of Co/Ni and activates them. DFT calculations also confirm the catalytic transition step of NiCoP can change from Heyrovsky (2.71 eV) to Tafel step (0.51 eV) in the neighborhood of Pt, in accord with the result of the improved Hads at the interface disclosed by in situ electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) tests. [ABSTRACT FROM AUTHOR]

Photo(electro)catalysts use sunlight to drive chemical reactions such as water splitting. A major factor limiting photocatalyst development is physicochemical heterogeneity which leads to spatially dependent reactivity. To link structure and function in such systems, simultaneous probing of the electrochemical environment at microscopic length scales and a broad range of timescales (ns to s) is required. Here, we address this challenge by developing and applying in-situ (optical) microscopies to map and correlate local electrochemical activity, with hole lifetimes, oxygen vacancy concentrations and photoelectrode crystal structure. Using this multi-modal approach, we study prototypical hematite (α-Fe2O3) photoelectrodes. We demonstrate that regions of α-Fe2O3, adjacent to microstructural cracks have a better photoelectrochemical response and reduced back electron recombination due to an optimal oxygen vacancy concentration, with the film thickness and extended light exposure also influencing local activity. Our work highlights the importance of microscopic mapping to understand activity, in even seemingly homogeneous photoelectrodes. Physicochemical heterogeneity poses a significant constraint in photocatalyst advancement. Here the authors introduce a multimodal optical microscopy platform to assess activity and defects concurrently in photoelectrocatalysts, revealing that disorder can unexpectedly enhance local photoelectrocatalytic performance in certain instances. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) conjugated with polymers are well-known for their powerful and effective antimicrobial properties. In particular, the incorporation of AgNPs in biocompatible catecholamine-based polymers, such as polydopamine (PDA), has recently shown promising antimicrobial activity, due to the synergistic effects of the AgNPs, silver(I) ions released and PDA. In this study, we generated AgNPs-PDA-patterned surfaces by localised electrochemical depositions, using a double potentiostatic method via scanning electrochemical cell microscopy (SECCM). This technique enabled the assessment of a wide parameter space in a high-throughput manner. The optimised electrodeposition process resulted in stable and homogeneously distributed AgNP-microspots, and their antimicrobial activity against Escherichia coli was assessed using atomic force microscopy (AFM)-based force spectroscopy, in terms of bacterial adhesion and cell elasticity. We observed that the bacterial outer membrane underwent significant structural changes, when in close proximity to the AgNPs, namely increased hydrophilicity and stiffness loss. The spatially varied antimicrobial effect found experimentally was rationalised by numerical simulations of silver(I) concentration profiles. [ABSTRACT FROM AUTHOR]

Scanning electrochemical cell microscopy (SECCM) has emerged as a transformative technology for electrochemical materials characterisation and the study of single entities, garnering global adoption by numerous research groups. While details on the instrumentation and operational principles of SECCM are readily available, the growing need for practical guidelines, troubleshooting strategies, and a systematic overview of applications and trends has become increasingly evident. This tutorial review addresses this gap by offering a comprehensive guide to the practical application of SECCM. The review begins with a discussion of recent developments and trends in the application of SECCM, before providing systematic approaches to (and the associated troubleshooting associated with) instrumental set up, probe fabrication, substrate preparation and the deployment of environmental (e.g., atmosphere and humidity) control. Serving as an invaluable resource, this tutorial review aims to equip researchers and practitioners entering the field with a comprehensive guide to essential considerations for conducting successful SECCM experiments. [ABSTRACT FROM AUTHOR]

This article, published in Chemical Communications, explores the electrochemical reduction of CO2 on molybdenite (MoS2) electrocatalysts. The study utilizes scanning electrochemical cell microscopy (SECCM) to directly observe the activity of different surface structures of MoS2 in reducing CO2. The findings reveal that nanoscale defects, particularly those with exposed edge planes, demonstrate higher overall activity in CO2 reduction compared to the relatively inactive basal plane. This research offers valuable insights for the development of cost-effective electrocatalysts for large-scale CO2 electrolysis. The study focuses on the electrochemical reduction of carbon dioxide (CO2) on 2H-MoS2 using scanning electrochemical cell microscopy (SECCM). It investigates the impact of various structural features, such as creases, step edges, and nanoflakes, on the electrocatalytic activity of 2H-MoS2. The results indicate that creases and step edges exhibit enhanced CO2 reduction activity compared to the bulk material, while nanoflakes are highly active but not selective for CO2 reduction. These findings contribute to our understanding of the structure-activity relationships of 2H-MoS2 in CO2 electroreduction. [Extracted from the article]

Electrochemical nucleation and growth (EN&G) is an inherently dynamic process governed by atomic-level interactions. Understanding the electrochemical phase formation on foreign substrates presents a formidable challenge at the fundamental level. One of the main challenges lies in uncovering both the energetic state of the substrate and the complex interaction between the substrate and the newly formed phase at the "electrode–electrolyte" interface. Furthermore, obtaining direct, unconvoluted, information is not straightforward due to the intricate nature of the phase boundary and phase formation process. In this work, we explore the EN&G from a local perspective by independently probing hundreds of different surface regions with scanning electrochemical cell microscopy (SECCM), providing a novel perspective and insights into the activity distribution and role of the substrate state in the nucleation process. We highlight the significance of acknowledging the diversity at the microscopic scale by summarizing the electrochemical profiles with statistical measures and observing their temporal- or potential-dependent evolution. Our results show that the energy required for the formation of stable nuclei on active sites varies due to surface heterogeneities, significantly impacting the overpotential required on low-energy and high-energy substrates. Upon a cross-system examination, trends emerge thanks to our high-throughput approach. Although nucleation is driven by the most active sites, we observe that it is possible to probe less active sites. Interestingly, these can significantly change their activity after being subjected to polarization. Non-uniform distributions of nucleation activity are disclosed and can be best fitted with two expressions: lognormal and Weibull. The understanding of these distributions is the bridge connecting the microscopic information to macroscopic outcomes, shedding light on how surface heterogeneities influence nucleation rates and deposition behaviors. Characterizing the distribution provides valuable insights into the underlying mechanism, offering a deeper understanding of the nature of active sites and highlighting the capabilities of our local approach for leveraging data-driven analysis. [ABSTRACT FROM AUTHOR]

To explore the influence of electrolyte concentration, single pulse energy, current density and scan times on the hydrophobic properties of laser-assisted electrochemical composite etching 2024 aluminum alloy surface, the experimental platform of laser-assisted electrochemical composite etching is built. Based on the results of the single-factor experiments, the response surface method (RSM) is chosen to optimize the process parameters. The optimum combination of process parameters is obtained, and the accuracy of the regression equation is verified by experiments. Through residual analysis, the established regression model fits well. By analysis of variance (ANOVA), the sequence of influence of the factors on apparent contact angle (from large to small) is single pulse energy, scan times, electrolyte concentration, and current density. With the maximum apparent contact angle as the goal, the combination of process parameters adjusted after optimization is: electrolyte concentration 2.0 mol/L, single pulse energy 20µJ, current density 18 mA, and scan times 15. Under these conditions, the experimental values of apparent contact angle is 157°, which is close to the predicted value (158°) by the models. The relative errors is 0.6%. It indicates that the regression model is accurate and reliable. This study shows that RSM is an effective method to optimize the process parameters and obtain the ideal experimental results. [ABSTRACT FROM AUTHOR]

Multi‐principal element alloys (MPEAs) are gaining interest in corrosion and electrocatalysis research due to their electrochemical stability across a broad pH range and the design flexibility they offer. Using the equimolar CrCoNi alloy, we observe significant metal dissolution in a corrosive electrolyte (0.1 M NaCl, pH 2) concurrently with the oxygen evolution reaction (OER) in the transpassive region, despite the absence of hysteresis in polarization curves or other obvious corrosion indicators. We present a characterization scheme to delineate the contribution of OER and alloy dissolution, using scanning electrochemical microscopy (SECM) for OER‐onset detection, and quantitative chemical analysis with inductively coupled‐mass spectrometry (ICP‐MS) and ultraviolet visible light (UV/Vis) spectrometry to elucidate metal dissolution processes. In situ electrochemical atomic force microscopy (EC‐AFM) revealed that the transpassive metal dissolution on CrCoNi is dominated by intergranular corrosion. These results have significant implications for the stability of MPEAs in corrosion systems, emphasizing the necessity of analytically determining metal ions released from MPEA electrodes into the electrolyte when evaluating Faradaic efficiencies of OER catalysts. The release of transition metal ions not only reduces the Faradaic efficiency of electrolyzers but may also cause poisoning and degradation of membranes in electrochemical reactors. [ABSTRACT FROM AUTHOR]

The toxicity of emerging organic pollutants to photosystems of aquatic plants is still not well clarified. This study aimed to develop a novel ecotoxicological experimental protocol based on nanoscale electrochemical mapping of photosynthetic oxygen evolution of aquatic plants by scanning electrochemical microscopy (SECM). The protocol was also checked by confocal laser scanning microscopy (CLSM), the traditional Clark oxygen electrode method, and the chlorophyll fluorescence technique. The typical persistent organic pollutant 2,4-dichlorophenol (2,4-DCP) in a water environment and the common aquatic Microsorium pteropus (M. pteropus) were chosen as the model organic pollutant and tested plant, respectively. It was found that the SECM method could discriminate the responses of stoma micromorphology and spatial pattens of photosynthetic oxygen evolution on single stoma well. The shape of stoma blurred with increasing 2,4-DCP concentration, which was in good agreement with the CLSM images. The dose–response curves and IC50 values obtained from the SECM data were verified by the data measured by the traditional Clark oxygen electrode method and chlorophyll fluorescence test. The IC50 value of single-stoma oxygen emission of plant leaves exposed for 24 h, which was derived from the SECM current data (32,535 μg L−1), was close to those calculated from the maximum photosynthetic efficiency (Fv/Fm) measured by the chlorophyll fluorescence test (33,963 μg L−1) and the Clark oxygen electrode method photosynthetic oxygen evolution rate (32,375 μg L−1). The 72 h and 96 h 2,4-DCP exposure data further confirmed the reliability of the nanoscale stoma oxygen emission mapping methodology for ecotoxicological assessment. In this protocol, the procedures for how to collect effective electrochemical data and how to extract useful information from the single-stoma oxygen emission pattern were well established. This study showed that SECM is a feasible and reliable ecotoxicological tool for evaluation of toxicity of organic pollutants to higher plants with a unique nanoscale visualization advantage over the conventional methods. [ABSTRACT FROM AUTHOR]

The scarcity of state‐of‐the‐art oxygen evolution reaction (OER) electrocatalysts has led to intensive research on alternative viable electrocatalytic materials. While activity and cost are the main factors to be sought after, the catalyst stability under harsh acidic conditions is equally crucial. Considering that OER is a proton‐coupled electron‐transfer reaction that involves local acidification of the reaction environment by liberation of H+, the catalyst stability can be largely compromised in such conditions. Consequently, probing the pH value near the catalyst surface under operation leads to a deeper understanding of this process. The applicability of bare Au microelectrodes and nanoelectrodes as sensitive local pH probes during OER is shown in this work by using scanning electrochemical microscopy (SECM). Two case studies are presented, including the state‐of‐the‐art OER catalyst (IrO2) in acidic media and a ZnGa2O4 catalyst in alkaline buffered solution, demonstrating the suitability of the Au probe to accurately determine the local pH value in a wide pH range. [ABSTRACT FROM AUTHOR]

The development of new technologies for the current energy and environmental challenges requires the acquisition of a very fundamental knowledge about the structure and activity of catalytic materials at the nanometric scale. As a consequence, in situ and operando methodologies are blossoming, but only a fraction of them really aims at a local vision that would allow watching atoms at work during reactions. In this short report, we want to outline the merits of a new technique based on scanning tunnelling microscopy (Current-roughness electrochemical scanning tunneling microscopy, cr-EC-STM) which can visualize electrocatalytic reactions down at the single atom level. Results of two case studies in the field of hydrogen evolution reaction (HER) are briefly summarized, witnessing the capability of cr-EC-STM to provide critical information about the structure and catalytic performance of the active sites with atomic resolution. [ABSTRACT FROM AUTHOR]

This communication introduces a quick and easy method to modify a typical disk electrode's surface geometry. The method involves masking fragments of the flat surface of the working electrode, by applying a specific thin layer of chemically stable insulating material, leaving unvarnished, electrochemically active surface. Desired shapes are achieved by using a properly laser-engraved stainless-steel plate and a stamper to transfer the profiled varnish from the steel plate to the surface of the electrode. Three shapes - microdisk, microband, and ring electrodes - were applied to a platinum disk electrode, validated through optical and scanning electrochemical microscopies, and cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Forisomes are giant structural plant mechanoproteins that reversibly undergo a transition from a longitudinally expanded to a contracted (dispersed) state. This transition is driven by a change in the concentration of Ca2+ ions. Artificial forisomes, expressed in yeast, have a width of 0.7 µm and a length of 4.6 µm and adsorb onto a gold surface. Scanning electrochemical microscopy imaging of the adsorbed forisomes reveales a heterogenous film in which several proteins adsorb together on the substrate surface. The adsorbed forisomes maintain their biological activity and undergo reversible contraction–expansion reactions. Infrared spectroscopy (IRS) shows that Ca2+ ions are coordinated to the carboxylate groups in the side chains of Asp and Glu affecting the 3D arrangement of the corresponding protein fragments allowing for a longitudinal contraction, dispersion of the forisome volume, and water uptake. In films, expanded forisomes accumulate small ions (ethylendiaminetetraacetic acid dianion or [Fe(CN)6]4‐) that are released upon Ca2+ driven dispersion. The properties described here make forisomes attractive for biotechnological applications. [ABSTRACT FROM AUTHOR]