Electrochemical Skeletal Indole Editing via Nitrogen Atom Insertion by Sustainable Oxygen Reduction Reaction.

Skeletal molecular editing gained considerable recent momentum and emerged as a uniquely powerful tool for late-stage diversifications. Thus far, superstoichiometric amounts of costly hypervalent iodine(III) reagents were largely required for skeletal indole editing. In contrast, we herein show that electricity enables sustainable nitrogen atom insertion reactions to give bio-relevant quinazoline scaffolds without stoichiometric chemical redox-waste product. The transition metal-free electro-editing was enabled by the oxygen reduction reaction (ORR) and proved robust on scale, while tolerating a variety of valuable functional groups.

Chirality-Induced Spin Selectivity Enables New Breakthrough in Electrochemical and Photoelectrochemical Reactions.

To facilitate the transition from a carbon-energy-dependent society to a sustainable society, conventional engineering strategies, which encounter limitations associated with intrinsic material properties, should undergo the paradigm shift. From a theoretical viewpoint, the spin-dependent feature of oxygen evolution reaction (OER) reveals the potential of a spin-polarization strategy in enhancing the performance of electrochemical (EC) reactions. The chirality-induced spin selectivity (CISS) phenomenon attracts unprecedented attention owing to its potential utility in achieving novel breakthroughs. This paper starts with the experimental results aimed at enhancing the efficiency of the spin-dependent OER focusing on the EC system based on the CISS phenomenon. The applicability of spin-polarization to EC system is verified through various analytical methodologies to clarify the theoretical groundwork and mechanisms underlying the spin-dependent reaction pathway. The discussion is then extended to effective spin-control strategies in photoelectrochemical system based on the CISS effect. Exploring the influence of spin-state control on the kinetic and thermodynamic aspects, this perspective also discusses the effect of spin polarization induced by the CISS phenomenon on spin-dependent OER. Lastly, future directions for enhancing the performance of spin-dependent redox systems are discussed, including expansion to various chemical reactions and the development of materials with spin-control capabilities.

A Rechargeable "Rocking Chair" Type Zn-CO2 Battery.

Rising global temperatures and critical energy shortages have spurred researches into CO2 fixation and conversion within the realm of energy storage such as Zn-CO2 batteries. However, traditional Zn-CO2 batteries employ double-compartment electrolytic cells with separate carriers for catholytes and anolytes, diverging from the "rocking chair" battery mechanism. The specific energy of these conventional batteries is constrained by the solubility of discharge reactants/products in the electrolyte. Additionally, H2O molecules tend to trigger parasitic reactions at the electrolyte/electrode interfaces, undermining the long-term stability of Zn anodes. In this report, we introduce an innovative "rocking chair" type Zn-CO2 battery that utilizes a weak-acidic Zn(OTf)2 aqueous electrolyte compatible with both cathode and anode. This design minimizes side reactions on the Zn surface and leverages the high catalytic activity of the cathode material, allowing the battery to achieve a substantial discharge capacity of 6734 mAh g-1 and maintain performance over 65 cycles. Moreover, the successful production of pouch cells demonstrates the practical applicability of Zn-CO2 batteries. Electrode characterizations confirm superior electrochemical reversibility, facilitated by solid discharge products of ZnCO3 and C. This work advances a "rocking chair" Zn-CO2 battery with enhanced specific energy and a reversible pathway, providing a foundation for developing high-performance metal-CO2 batteries.

A comprehensive review of the application of Zr-based metal-organic frameworks for electrochemical sensors and biosensors.

A family of inorganic-organic hybrid crystalline materials made up of organic ligands and metal cations or clusters is known as metal-organic frameworks (MOFs). Because of their unique stability, intriguing characteristics, and structural diversity, zirconium-based MOFs (Zr-MOFs) are regarded as one of the most interesting families of MOF materials for real-world applications. Zr-MOFs that have the ligands, metal nodes, and guest molecules enclosed show distinct electrochemical reactions. They can successfully and sensitively identify a wide range of substances, which is important for both environmental preservation and human health. The rational design and synthesis of Zr-MOF electrochemical sensors and biosensors, as well as their applications in the detection of drugs, biomarkers, pesticides, food additives, hydrogen peroxide, and other materials, are the main topics of this comprehensive review. We also touch on the current issues and potential future paths for Zr-MOF electrochemical sensor research.

Applications of Electrophotocatalysis in C-H Functionalization of Organic Molecules.

Electrophotocatalysis (EPC) has evolved as a new scientific discipline around the boundary of highly active fields: electrochemistry and photocatalysis. EPC allows us to combine the energy of light and electric potential to activate previously inaccessible compounds via single-electron transfer (SET). Herein, we review the most essential applications of EPC to the C-H functionalization of molecules. This work discusses mechanisms that can be encountered when designing such processes and analyzes technical aspects of performing EPC reactions in the laboratory.

Oxygen-Assisted Supercapacitive Swing Adsorption of Carbon Dioxide.

We report on the supercapacitive swing adsorption (SSA) of carbon dioxide at different voltage windows in the presence of oxygen using activated carbon electrodes, and deliquescent, aqueous electrolytes. The presence of O2 in the CO2/N2 gas mixture results in an up to 11 times higher CO2 adsorption capacity with 3M MgBr2 (at 0.6V) and up to 4-5 times higher adsorption capacity with 3M MgCl2 (at 1V). A tradeoff between high CO2 adsorption capacities and lower coulombic efficiencies was observed at voltages above 0.6V. The energetic and adsorptive performance of the electrodes in the presence of oxygen below 0.5V was similar to the performance with a CO2/N2 mixture without oxygen at 1V. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of the electrodes demonstrate that the specific capacitance increases while the diffusion resistance decreases in the presence of oxygen. Oxygen concentrations ranging between 5-20% give similar energetic and adsorptive performance. The electrodes exhibit stable performance for up to 100 cycles of operation.

A solid state electrolyte based enzymatic acetone sensor.

This paper introduces a novel solid-state electrolyte-based enzymatic sensor designed for the detection of acetone, along with an examination of its performance under various surface modifications aimed at optimizing its sensing capabilities. To measure acetone concentrations in both liquid and vapor states, cyclic voltammetry and amperometry techniques were employed, utilizing disposable screen-printed electrodes consisting of a platinum working electrode, a platinum counter electrode, and a silver reference electrode. Four different surface modifications, involving different combinations of Nafion (N) and enzyme (E) layers (N + E; N + E + N; N + N + E; N + N + E + N), were tested to identify the most effective configuration for a sensor that can be used for breath acetone detection. The sensor's essential characteristics, including linearity, sensitivity, reproducibility, and limit of detection, were thoroughly evaluated through a range of experiments spanning concentrations from 1 µM to 25 mM. Changes in acetone concentration were monitored by comparing currents readings at different acetone concentrations. The sensor exhibited high sensitivity, and a linear response to acetone concentration in both liquid and gas phases within the specified concentration range, with correlation coefficients ranging from 0.92 to 0.98. Furthermore, the sensor achieved a rapid response time of 30-50 s and an impressive detection limit as low as 0.03 µM. The results indicated that the sensor exhibited the best linearity, sensitivity, and limit of detection when four layers were employed (N + N + E + N).

Biofunctional photoelectrochemical/electrochemical immunosensor based on BiVO4/BiOI-MWCNTs and Au@PdPt for alpha-fetoprotein detection.

A biofunctional immunosensor combining photoelectrochemical (PEC) and electrochemical (EC) was proposed for the quantitative detection of the liver cancer marker alpha-fetoprotein (AFP) in human blood. BiVO4/BiOI-MWCNTs photoactive materials were first prepared on conductive glass FTO, and the photoelectrode was functionalized by chitosan and glutaraldehyde. Then, the AFP capture antibody (Ab1) was successfully modified on the photoelectrode, and the label-free rapid detection of AFP antigen was achieved by PEC. In addition, Au@PdPt nanospheres were also used as a marker for binding to AFP detection antibody (Ab2). Due to the excellent catalytic properties of Au@PdPt in EC reaction, a signal increase in the EC response can be achieved when Ab2 binds to the AFP antigen, which ensures high sensitivity for the detection of AFP. The detection limits of PEC and EC are 0.050 pg/mL and 0.014 pg/mL, respectively. The sensor also possesses good specificity, stability and reproducibility, shows excellent performance in the detection of clinical samples and has good clinical applicability.

Origin of O2 Generation in Sulfide-Based All-Solid-State Batteries and its Impact on High Energy Density.

The cathode surface of sulfide-based all-solid-state batteries (SBs) is commonly coated with amorphous-LiNbO3 in order to stabilize charge-discharge reactions. However, high-voltage charging diminishes the advantages, which is caused by problems with the amorphous-LiNbO3 coating layer. This study has investigated the degradation of amorphous-LiNbO3 coating layer directly during the high-voltage charging of SBs. O2 generation via Li extraction from the amorphous-LiNbO3 coating layer is observed using electrochemical gas analysis and electrochemical X-ray photoelectron spectroscopy. This O2 leads to the formation of an oxidative solid electrolyte (SE) around the coating layer and degrades the battery performance. On the other hand, elemental substitution (i.e., amorphous-LiNbxP1- xO3) reduces O2 release, leading to stable high-voltage charge-discharge reactions of SBs. The results have emphasized that the suppression of O2 generation is a key factor in improving the energy density of SBs.

A High-Performance, Low Defected, and Binder-free Graphene-based Supercapacitor Obtained via Synergistic Electrochemical Exfoliation and Electrophoretic Deposition Process.

An integrated electrochemical exfoliation and electrophoretic deposition (EPD) method is developed to achieve a high performance graphene supercapacitor. The electrochemical delamination of graphite sheet has obtained a low defected few-layer graphene adorned with oxygen-containing functional groups. Then, the EPD process produced a binder-free electrode to alleviate the graphene restacking problem. The electrode prepared using a deposition voltage of 5V exhibits the highest specific capacitance of 145.95 F/g at 0.5 A/g from three-electrode measurement. Moreover, this EPD-prepared electrode also demonstrates superior electrochemical properties compared to electrodes fabricated using PVDF binder. In the real symmetrical cell, the EPD-prepared electrode also shows excellent performance with a high rate capability of 82.31% (from 0.5 A/g to 10 A/g), high cycling stability of 95.00% (at 5 A/g) after 10,000 cycles, and rapid frequency response with short relaxation time (τ0) of 9.73 ms. These results indicate that this integration method is beneficial to construct a high performance binder-free supercapacitor electrode consisting of low-defected graphene materials, low electrode resistance, and less agglomeration of graphene sheets by utilizing an environmentally friendly process.

Lithium-coupled electron transfer reactions of nano-confined WOx within Zr-based metal-organic framework.

Interfacial charge transfer reactions involving cations and electrons are fundamental to (photo/electro) catalysis, energy storage, and beyond. Lithium-coupled electron transfer (LCET) at the electrode-electrolyte interfaces of lithium-ion batteries (LIBs) is a preeminent example to highlight the importance of charge transfer in modern-day society. The thermodynamics of LCET reactions define the minimal energy for charge/discharge of LIBs, and yet, these parameters are rarely available in the literature. Here, we demonstrate the successful incorporation of tungsten oxides (WOx) within a chemically stable Zr-based metal-organic framework (MOF), MOF-808. Cyclic voltammograms (CVs) of the composite, WOx@MOF-808, in Li+-containing acetonitrile (MeCN)-based electrolytes showed an irreversible, cathodic Faradaic feature that shifted in a Nernstian fashion with respect to the Li+ concentration, i.e., ∼59 mV/log [(Li+)]. The Nernstian dependence established 1:1 stoichiometry of Li+ and e-. Using the standard redox potential of Li+/0, the apparent free energy of lithiation of WOx@MOF-808 (ΔGapp,Li) was calculated to be -36 ± 1 kcal mol-1. ΔGapp,Li is an intrinsic parameter of WOx@MOF-808, and thus by deriving the similar reaction free energies of other metal oxides, their direct comparisons can be achieved. Implications of the reported measurements will be further contrasted to proton-coupled electron transfer (PCET) reactions on metal oxides.

Hybrid nanoflower-based electrochemical lateral flow immunoassay for Escherichia coli O157 detection.

An electrochemical biosensor has been developed for detection of Escherichia coli O157 by integrating lateral flow with screen-printed electrodes. The screen-printed electrodes were attached under the lateral flow detection line, and organic-inorganic nanoflowers prepared from E. coli O157-specific antibodies as an organic component were attached to the lateral flow detection line. In the presence of E. coli O157, an organic-inorganic nanoflower-E. coli O157-antimicrobial peptide-labelled ferrocene sandwich structure is formed on the lateral flow detection line. Differential pulse voltammetry is applied using a smartphone-based device to monitor ferrocene on the detection line. The resulting electrochemical biosensor could specifically detect E. coli O157 with a limit of detection of 25 colony-forming units mL-1. Through substitution of antibodies of organic components in organic-inorganic nanoflowers, biosensors have great potential for the detection of other pathogens in biomedical research and clinical diagnosis.

Rapid, Point-of-Care Microwave Lysis and Electrochemical Detection of Clostridioides difficile Directly from Stool Samples.

The rapid detection of the spore form of Clostridioides difficile has remained a challenge for clinicians. To address this, we have developed a novel, precise, microwave-enhanced approach for near-spontaneous release of DNA from C. difficile spores via a bespoke microwave lysis platform. C. difficile spores were microwave-irradiated for 5 s in a pulsed microwave electric field at 2.45 GHz to lyse the spore and bacteria in each sample, which was then added to a screen-printed electrode and electrochemical DNA biosensor assay system to identify presence of the pathogen's two toxin genes. The microwave lysis method released both single-stranded and double-stranded genome DNA from the bacterium at quantifiable concentrations between 0.02 µg/mL to 250 µg/mL allowing for subsequent downstream detection in the biosensor. The electrochemical bench-top system comprises of oligonucleotide probes specific to conserved regions within tcdA and tcdB toxin genes of C. difficile and was able to detect 800 spores of C. difficile within 300 µL of unprocessed human stool samples in under 10 min. These results demonstrate the feasibility of using a solid-state power generated, pulsed microwave electric field to lyse and release DNA from human stool infected with C. difficile spores. This rapid microwave lysis method enhanced the rapidity of subsequent electrochemical detection in the development of a rapid point-of-care biosensor platform for C. difficile.

Detection of aldehydes from degradation of lipid nanoparticle formulations using a hierarchically-organized nanopore electrochemical biosensor.

Degradation of ionizable lipids in mRNA-based vaccines was recently found to deactivate the payload, demanding rigorous monitoring of impurities in lipid nanoparticle (LNP) formulations. However, parallel screening for lipid degradation in customized delivery systems for next-generation therapeutics maintains a challenging and unsolved problem. Here, we describe a nanopore electrochemical sensor to detect ppb-levels of aldehydes arising from lipid degradation in LNP formulations that can be deployed in massively parallel fashion. Specifically, we combine nanopore electrodes with a block copolymer (BCP) membrane capable of hydrophobic gating of analyte transport between the bulk solution and the nanopore volume. By incorporating aldehyde dehydrogenase (ALDH), enzymatic oxidation of aldehydes generates NADH to enable ultrasensitive voltammetric detection with limits-of-detection (LOD) down to 1.2 ppb. Sensor utility was demonstrated by detecting degradation of N-oxidized SM-102, the ionizable lipid in Moderna's SpikeVax™ vaccine, in mRNA-1273 LNP formulation. This work should be of significant use in the pharmaceutical industry, paving the way for automated on-line quality assessments of next-generation therapeutics.

A Class of Sodium Transition-Metal Sulfide Cathodes With Anion Redox.

Sodium-ion batteries (SIBs) are entering commercial relevance as a sustainable and low-cost alternative to lithium-ion batteries. Improving the energy density of SIBs is critical to enable their widespread adoption. Here, a new class of cathode materials Na6MS4 (M = Co, Mn, Fe, and Zn) that exhibit high charge-storage capacity is reported. Using Na6CoS4 as a prototypical example, a six-electron conversion reaction dominated by anion redox is observed, confirmed through various electrochemical and spectroscopic techniques. After the initial cycle, Na6CoS4 delivers a high capacity of 392 mA h g-1 with a long lifespan of over 500 cycles. The reaction involves, initially, the transformation of crystalline Na6CoS4 to a nearly amorphous structure consisting of mainly CoS and sulfur nanoparticles, which then reversibly cycles between nearly amorphous a-CoS/S and a-Na6CoS4. Such anion-redox-driven conversion-type cathodes hold the potential to enable energy-dense, stable SIBs.

Aptamer-based electrochemical nanobiosensor for research and monitoring of multiple sclerosis in mice models.

Multiple sclerosis (MS) is a severe progressive autoimmune-inflammatory, demyelinating process in the central nervous system (CNS) with heterogeneous neurological symptoms appearing as a consequence of myelin break down. Myelin basic protein (MBP) makes up to 30 % of the CNS myelin [1] and it is known to be released into the cerebrospinal fluid (CSF) as a bioindicator of MS. Autoimmune encephalomyelitis (EAE) is a mice model of MS widely used for research and development of new treatments [2]. Herein, MBP specific aptamer developed for possible therapeutic purposes in mouse model [3] was applied as a bioreceptor for MBP recognition. A nanobiosensor for MBP detection and monitoring was developed by using graphene oxide (GO) nanoparticles integrated onto the screen-printed carbon electrodes (SPCE) and aptamer immobilized to create a bioactive layer on the sensor surface for MBP binding. The measurements were carried out using electrochemical impedance spectrometry (EIS). Validation studies were carried out in a biological matrix (artificial CSF) containing MBP, and MSA. The aptasensor had LOD in artificial CSF 0.01 ng/mL and showed its usability in the concentration range of 0.01 … 64 ng/mL.

Electrode and Electrolyte Co-Energy-Storage Electrochemistry Enables High-Energy Zn-S Decoupled Batteries.

In the search for next-generation green energy storage solutions, Cu-S electrochemistry has recently gained attraction from the battery community owing to its affordability and exceptionally high specific capacity of 3350 mAh gs -1. However, the inferior conductivity and substantial volume expansion of the S cathode hinder its cycling stability, while the low output voltage limits its energy density. Herein, a hollow carbon sphere (HCS) is synthesized as a 3D conductive host to achieve a stable S@HCS cathode, which enables an outstanding cycling performance of 2500 cycles (over 9 months). To address the latter, a Zn//S@HCS alkaline-acid decoupled cell is configured to increase the output voltage from 0.18 to 1.6 V. Moreover, an electrode and electrolyte co-energy storage mechanism is proposed to offset the reduction in energy density resulting from the extra electrolyte required in Zn//S decoupled cells. When combined, the Zn//S@HCS alkaline-acid decoupled cell delivers a record energy density of 334 Wh kg-1 based on the mass of the S cathode and CuSO4 electrolyte. This work tackles the key challenges of Cu-S electrochemistry and brings new insights into the rational design of decoupled batteries.

X-ray Spectroscopy at the SuperXAS and Debye Beamlines: from in situ to Operando.

Understanding structure-performance relationships are essential for the rational design of new functional materials or in the further optimization of (catalytic) processes. Due to the high penetration depth of the radiation used, synchrotron-based hard X-ray techniques (with energy > 4.5 keV) allow the study of materials under realistic conditions (in situ and operando) and thus play an important role in uncovering structure-performance relationships. X-ray absorption and emission spectroscopies (XAS and XES) give insight into the electronic structure (oxidation state, spin state) and local geometric structure (type and number of nearest neighbor atoms, bond distances, disorder) up to ~5 Å around the element of interest. In this mini review, we will give an overview of the in situ and operando capabilities of the SuperXAS beamline, a facility for hard X-ray spectroscopy, through recent examples from studies of heterogeneous catalysts, electrochemical systems, and photoinduced processes. The possibilities for time-resolved experiments in the time range from ns to seconds and longer are illustrated. The extension of X-ray spectroscopy at the new Debye beamline combined with operando X-ray scattering and diffraction and further developments of time-resolved XES at SuperXAS will open new possibilities after the Swiss Light Source upgrade mid 2025.

Operando Neutron Imaging.

In the past, neutron imaging has been the little brother of advanced neutron spectroscopy techniques due to its apparent simplicity. However, this simplicity allows the studying of complex chemical and electrochemical processes and related devices even under harsh reaction conditions such as high pressure, high temperature, corrosive and/or air sensitive environments. We review a number of highly relevant case studies as archetypal examples of modern energy technology; that is heat storage, power-to-X, batteries, fuel cells, and catalysis. The promising results trigger the further development of neutron imaging towards a chemical imaging method.

Electrochemical Monitoring of Real-Time Vesicle Dynamics Induced by Tau in a Confined Nanopipette.

The microtubule-associated protein tau participates in neurotransmission regulation via its interaction with synaptic vesicles (SVs). The precise nature and mechanics of tau's engagement with SVs, especially regarding alterations in vesicle dynamics, remain a matter of discussion. We report an electrochemical method using a synapse-mimicking nanopipette to monitor vesicle dynamics induced by tau. A model vesicle of ~30 nm is confined within a lipid-modified nanopipette orifice with a comparable diameter to mimic the synaptic lipid environment. Both tau and phosphorylated tau (p-tau) present two-state dynamic behavior in this biomimetic system, showing typical ionic current oscillation, induced by lipid-tau interaction. The results indicate that p-tau has a stronger affinity to the lipid vesicles in the confined environment, blocking the vesicle movement to a higher degree. Taken together, this method bridges a gap for sensing synaptic vesicle dynamics in a confined lipid environment, mimicking vesicle movement near the synaptic membrane. These findings contribute to understanding how different types of tau protein regulate synaptic vesicle motility and to underlying its functional and pathological behaviours in disease.