Electrode Surface Research Articles

PEDOT:PSS Electropolymerization Protocol for Microelectrodes Enabling Low‐Cost Impedance‐Based Cellular Assays

ABSTRACTElectric cell‐substrate impedance sensing (ECIS) is a label‐free method for in vitro cell analysis in different research fields such as virology, cancer research, and stem cell research. In the ECIS configuration, the working electrode (WE) is typically much smaller than the counter electrode, thus the measured impedance between both is mainly dominated by the impedance of the WE. However, if the impedance of the WE is too high, it is challenging to detect small changes in impedance caused by cells attached to the electrode surface. In this study, we present an easily reproducible and cost‐effective method to lower the impedance of commercial ECIS electrodes, and by this increase the cell contribution in adhesion assays. Hereby we deposit a thin layer of poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) only onto the gold electrodes by electropolymerization and study the layer characteristics in detail. We compare cell‐free and cell‐covered impedance spectra of gold and PEDOT:PSS electrodes recorded with a low‐cost potentiostat and analyze the ECIS spectra of two different cell lines in detail.

Electronic Synergistic Effects on the Stability and Oxygen Evolution Reaction Efficiency of the Mesoporous LiMn2-xMxO4 (M = Mn, Fe, Co, Ni, and Cu) Electrodes.

Stable porous manganese oxide-based electrodes are essential for clean energy generation and storage because of their high natural abundance and health safety. This investigation focuses on mesoporous LiMn2-xMxO4 (where M is Fe, Co, Ni, and Cu and x is 0, 0.1, 0.3, 0.5, and 0.67) electrodes and thin/thick films. The mesoporous electrodes and films are fabricated by coating clear and homogeneous ethanol solutions of the salts (LiNO3, [Mn(OH2)4](NO3)2, and [M(OH2)x](NO3)2) and surfactants (P123 and CTAB) and calcining at elevated temperature (denoted as F-LiMn2-xMxO4, G-LiMn2-xMxO4, and meso-LiMn2-xMxO4, respectively). The electrochemical properties, stability, and oxygen evolution reaction (OER) performance of the F/G-LiMn2-xMxO4 electrodes are investigated in alkaline media using a three electrode setup. The F-LiMn1.33M0.67O4 electrodes (where M is Mn, Fe, Co, and Ni) exhibit low Tafel slopes of 60, 43, 44, and 32 mV/dec, respectively. While all the Mn-rich and F-LiMn2-xFexO4 electrodes degrade via Mn(VI) disproportionation reaction, the 33% Co electrode shows high stability during the OER. The nickel-based electrodes are stable with as little as 15% Ni and display excellent OER performance over 25% Ni, albeit undergoing a transformation that accumulates Ni(OH)2 species on the electrode surface. Copper in the F-LiMn2-xCuxO4 electrodes is homogeneous at low Cu percentages but forms a CuO phase above 15% Cu, undergoes degradation, and displays a weak OER performance. In short, Co and Ni stabilize the F-LiMn1.33Co0.67O4 and F-LiMn1.7Ni0.3O4 electrodes, which display excellent OER performance.

Integrated Carbon Dioxide Capture by Amines and Conversion to Methane on Single-Atom Nickel Catalysts.

Direct electrochemical reduction of carbon dioxide (CO2) capture species, i.e., carbamate and (bi)carbonate, can be promising for CO2 capture and conversion from point-source, where the energetically demanding stripping step is bypassed. Here, we describe a class of atomically dispersed nickel (Ni) catalysts electrodeposited on various electrode surfaces that are shown to directly convert captured CO2 to methane (CH4). A detailed study employing X-ray photoelectron spectroscopy (XPS) and electron microscopy (EM) indicate that highly dispersed Ni atoms are uniquely active for converting capture species to CH4, and the activity of single-atom Ni is confirmed using control experiments with a molecularly defined Ni phthalocyanine catalyst supported on carbon nanotubes. Comparing the kinetics of various capture solutions obtained from hydroxide, ammonia, primary, secondary, and tertiary amines provide evidence that carbamate, rather than (bi)carbonate and/or dissolved CO2, is primarily responsible for CH4 production. This conclusion is supported by 13C nuclear magnetic resonance (NMR) spectroscopy of capture solutions as well as control experiments comparing reaction selectivity with and without CO2 purging. These findings are understood with the help of density functional theory (DFT) calculations showing that single-atom nickel (Ni) dispersed on gold (Au) is active for the direct reduction of carbamate, producing CH4 as the primary product. This is the first example of direct electrochemical conversion of carbamate to CH4, and the mechanism of this process provides new insight on the potential for integrated capture and conversion of CO2 directly to hydrocarbons.

Optimizing protic ionic liquid electrolyte for pre-intercalated Ti3C2Tx MXene supercapacitor electrodes

Electrical double-layer capacitors (EDLCs) are of increasing importance in energy storage from renewable sources. The properties of the electrode and electrolyte materials influence the energy and power densities of EDLCs. We examined the specific capacitance and ion dynamics of a protic ionic liquid confined in pre-intercalated Ti3C2Tx MXene. Our electrochemical measurements demonstrated that the creation of a protic ionic liquid, 1-butyl-3-H-imidazolium bis(trifluoromethanesulfonyl)imide (BuIMH-NTf2), using a mixture of ionic liquid, 1-butyl imidazole (BuIM), and salt, bis(trifluoromethanesulfonyl)imide (HNTf2), in a ratio of 0.8:0.2 led to the optimal capacitance. Remarkably, quasi-elastic neutron scattering measurements revealed increased particle mobility at this composition, attributed to the more efficient accumulation of BuIMH+ on the electrode surface. This deposit of additional ions results in fewer BuIM molecules away from the surface, enhancing their mobility due to reduced crowding. This composition-dependent electrochemical behavior will guide the formulation of more efficient protic ionic liquid systems, enabling faster ion transport in energy storage devices.

Production of cost-effective green energy using Mn/Gd co-substituted cobalt ferrites hydroelectric cells and their oxygen evolution reaction

A thorough investigation into hydroelectric cells (HECs) composed of spinel ferrites, aiming to generate environmentally friendly electricity through the dissociation of water molecules into H3O+ and OH- ions without producing any harmful by-products has been reported. Utilizing a modified sol-gel auto-combustion synthesis method, we synthesized highly porous Mn2+/Gd3+ co-substituted cobalt ferrites (CFO) with the formula) [Co1-xMnxFe2-yGdyO4, 0≤x≤0.30 and y = 0.10]. X-ray diffraction (XRD) analysis revealed a singular-phase cubic structure, while Rietveld refinement provided essential parameters such as crystallite size, lattice constant, density, porosity percentage, and unit-cell volume. Morphological examination using Field emission scanning electron microscopy (FESEM) confirmed nanoparticle formation with an average size of 60.418 nm, and porosity increasing from 30 % to 51 % with Mn2+ ion doping, indicating enhanced water adsorption. XPS analysis highlighted increased lattice defects due to Mn/Gd co-substitution, boosting water adsorption capacity. Vibrating Sample Measurements showed a rise in Ms value with increasing Mn2+ concentration. Fabricated HECs delivered a maximum output current density of 13.906 mA/cm2, with 20 % Mn-substituted gadolinium cobalt ferrites-based HEC achieved a peak short-circuit current of 9.16 mA. These cells exhibited pseudo-capacitive behaviour, characterized by rapid and reversible faradaic reactions near electrode surfaces, while ionic diffusion mechanisms confirmed ion diffusion over the material's surface. Co1-xMnxGd0.1Fe1.9O4 (x = 0.20) is the optimal composition to get best OER performance having an overpotential of 342 mV at 10 mA/cm2 with a Tafel slope of 48 mV/dec in alkaline medium. This study underscores the potential of Mn2+/Gd3+ co-substituted cobalt ferrite as a promising alternative in green energy conversion applications, potentially replacing conventional fuel and solar cells. It has been concluded that the x = 0.20 is the composition that exhibits the best OER as well as HEC performance.

Highly Sensitive and Biocompatible Microsensor for Selective Dynamic Monitoring of Dopamine in Rat Brain.

Highly selective and sensitive in vivo neurotransmitter dynamic monitoring of the central nervous system has long been a challenging endeavor. Here, an implantable and biocompatible microsensor with excellent performances was reported by electrodepositing poly(3,4-ethylenedioxythiophene)-electrochemically reduced graphene oxide (PEDOT-ERGO) nanocomposites and poly(tannic acid) (pTA) sequentially on the carbon fiber electrode (CFE) surface, and its feasibility in in vivo electrochemical sensing applications were demonstrated. Due to the synergistic electrocatalytic effect of PEDOT-ERGO nanocomposites with the negative-charged pTA on dopamine (DA) redox reaction, the microsensor exhibits high detection sensitivities of 1.1 and 0.37 nA μM-1 in the detection ranges of 0.02-0.5 and 0.5-20 μM with a low limit of detection of 9.2 nM. Also, the microsensor shows excellent selectivity, good sensing stability, repeatability, and reproducibility. In addition, the highly hydrophilic and negative-charged pTA inhibits the nonspecific adsorption of hydrophobic proteins, which endows the microsensor with good antifouling ability. Moreover, DA dynamics in rat brain were successfully monitored in real time, and the selective sensing ability of the microsensor in vivo was also demonstrated. The present study provides a new method for selective dynamics monitoring of DA in the brain, which would help to better understand the pathological and physiological functions of DA.

Electropolymerization of a New Diketopyrrollopyrrole Derivative into Inherent Chiral Polymer Films

Electropolymerization is a convenient way to obtain conducting polymers (CPs) directly adhered to an electrode surface. CPs are well-known for their various application fields in photovoltaic cells, chemical sensors, and electronics. By implementing chirality into a CP, the application possibilities will spread further onto chiral sensors or optoelectronics. In this work, we introduce a new inherently chiral polymer based on a macrocyclic 3,4-ethylenedioxythiophene-diketopyrrolopyrrole-3,4-ethylenedioxythiophene triad (EDOT-DPP-EDOT) fused by 1,4-phenylene groups, which was prepared via oxidative electropolymerization directly on the electrode surface. The investigation of the chiroptical properties was performed by circular dichroism spectroscopy in the solid state. The enantiomeric pure polymer films obtained showed dissymmetry factors of up to −2.71 × 10−4, whereby linear dichroism contributions can be widely excluded.

Sodium‐Difluoro(oxalato)Borate‐Based Electrolytes for Long‐Term Cycle Life and Enhanced Low‐Temperature Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) are emerging as a promising alternative for next‐generation energy storage solutions, driven by the economic and environmental benefits of abundant sodium resources. A pivotal aspect of SIB advancement is the development of advanced electrolytes, which remains a formidable challenge. Herein, a facile and scalable synthesis method for low‐cost sodium‐difluoro(oxalato)borate (NaDFOB) is reported and explored its application as a standalone electrolyte salt for SIBs. The NaDFOB‐based ether electrolyte demonstrates exceptional electrochemical stability, solvent compatibility, and the unique capacity to form a dense, robust solid‐electrolyte interphase layer on electrode surfaces. As a result, the Na4Fe3(PO4)2P2O7 (NFPP) cathode with NaDFOB‐based electrolyte exhibits ultrahigh cycling stability with a remarkable capacity retention of 98.7% after 1000 cycles. Furthermore, an Ah‐level hard carbon (HC)//NFPP pouch cell using NaDFOB‐based ether electrolyte shows an impressive cycle life of 500 cycles, coupled with an average Coulombic efficiency of 99.9%. The pouch cells also maintain superior electrochemical performance across a broad temperature range from −40 to 60 °C, showcasing the electrolyte's versatility. This work contributes significant insights into the strategic design and application of innovative salts, paving the way for longer‐lasting SIBs with enhanced electrochemical performance.

Strong Ion‐Dipole Interactions for Stable Zinc‐Ion Batteries with Wide Temperature Range

AbstractAqueous zinc‐ion batteries are widely recognized as promising alternatives to lithium batteries due to their excellent safety, environmental compatibility, and cost‐effectiveness. Nonetheless, the formation of dendrites, corrosion, and undesirable side reactions on the zinc surface pose significant challenges to the cycling stability of zinc‐ion batteries. In this study, polar propylene carbonate (PC) is paired with tetrafluoroborate anions to establish a strong ion‐dipole interaction. Strong ion‐dipole interaction can not only alter the solvation structure of zinc ions but also facilitate the formation of a dynamic double electric layer on the surface of the zinc electrode, suppressing the formation of ZnF2 interface and carbonate, thereby facilitating uniform zinc ion deposition, and consequently improving battery cycling stability over a broad temperature range. Concretely, the formulated electrolyte enhances the cycling stability of the battery over a wide temperature range of −30 to 40 °C, accompanied by a capacity retention of ≈100% even after 10 000 cycles at −30 °C. The symmetrical battery utilizing this electrolyte exhibits stable cycling performance for over 1200 h at 25 °C and 1900 h at −30 °C, respectively. The findings provide a promising direction for the development of long‐cycle batteries capable of operating over a wide temperature range.

Surface functionalizing for high‐temperature ceramic fuel cells using electrochemical deposition technique

AbstractElectrochemical deposition technique, a method widely recognized for its precision and versatility in the electronics industry, is gaining attraction in the energy field, particularly in developing solid oxide fuel cells (SOFCs). Its ability to deposit metal compounds with nanostructures under simple ambient conditions makes it invaluable for modifying conventional electrodes with refined morphologies and compositions. In this mini‐review, we explore the principles of electrochemical deposition and highlight its recent applications in SOFC technology. Our focus lies on its pivotal role in fabricating coating layers or catalysts on electrodes with improved functionalities to build more efficient and durable fuel cells. Furthermore, we discuss emerging strategies for electrode surface modification and the potential of electrochemical deposition in advancing SOFC design and functionality. Our review also outlines future research directions aimed at harnessing and expanding the capabilities of electrochemical deposition in energy conversion applications.

A portable and sensitive DNA-based electrochemical sensor for detecting piconewton-scale cellular forces

BackgroundCell-generated forces are a key player in cell biology, especially during cellular shape formation, migration, cancer development, and immune response. The measurement of forces exerted and experienced by cells is fundamental in understanding these mechanosensitive cellular behaviors. While cell-generated forces can now be detected based on techniques like fluorescence microscopy, atomic force microscopy, optical/magnetic tweezers, however, most of these approaches rely on complicated instruments or materials, as well as skilled operators, which could limit their potential broad applications in regular biological laboratories. ResultsA new type of smartphone-based electrochemical sensor is developed here for cellular force measurement. In this system, a double-stranded DNA-based force probe, known as tension gauge tether, is attached to the surface of a gold screen-printed electrode, which is then incorporated into a portable smartphone-based electrochemical device. Cellular force-induced DNA detachment on the sensor surface results in multiple redox reporters to reach the surface of the electrode and generate enhanced electrochemical signals. To further improve the sensitivity, a CRISPR-Cas12a system has also been incorporated to cleave the remaining surface-attached anchor DNA strand. Using integrin-mediated tension as an example, piconewton-scale adhesion forces generated by ≤ 10 HeLa cells could now be reliably detected. Meanwhile, the threshold forces of these electrochemical sensors can also be modularly tuned to detect different levels of cellular forces. SignificanceThese novel DNA-based highly sensitive, portable, cost-efficient, and easy-to-use electrochemical sensors can be potentially powerful tools for detecting different cell-generated molecular forces. Functioning as complementary tools with traction force microscopy and fluorescent probes, these electrochemical sensors can be straightforwardly applied in regular biological laboratories for understanding the basic mechanical principles of cell signaling and for developing novel strategies and materials in tissue engineering, regenerative medicine, and cell therapy.

Sustained Regeneration of Hydrogen Peroxide at the Water-Gas Interface of Electrogenerated Microbubbles on an Electrode Surface.

Microbubbles, inside-out microdroplets, act as extraordinary microreactors to facilitate thermodynamically unfavorable reactions in bulk solutions of water. We explored the formation of hydrogen peroxide (H2O2) and its sustained regeneration at the interface of water-gas microbubbles. For this purpose, the chemiluminescence of luminol was recorded by a digital camera to map the intensity of blue light emission over the time of about 20 min. The formation and regeneration of hydrogen peroxide were also monitored by fluorescence microscopic imaging of a hydrogen peroxide probe. The microscopic images consistently show a stable glow around the microbubbles over time during which the formed hydrogen peroxide diffuses into the bulk solution. This observation confirms that the concentration of H2O2 at the interface is 30 times higher than that in the water solution bulk after several minutes, which can be attributed to its regeneration at the water-gas interface. These findings increase our understanding of why the chemistries of gas microbubbles in water and water microdroplets surrounded by gas are so distinct from those of bulk-phase water.

Influence of Electrolyte Saturation on the Performance of Li-O2 Batteries.

Electrolyte saturation can strongly affect the Li-O2 battery performance. However, it is unclear to what extent saturation reduction will impact the battery capacity. In this study, we investigated the influence of electrolyte saturation and distribution within a porous positive electrode on the deep discharge-charge capacities and cycling stability. The study used both models and experiments to investigate the change of electrolyte distribution, double-layer capacitance, ohmic resistance, and O2 concentration in the positive electrode at different electrolyte saturations. Results revealed that electrodes with 60% electrolyte saturation achieved almost the same maximum discharge (6.38 vs 6.76 mAh/cm2) and charge (5.52 vs 5.65 mAh/cm2) capacities with fully saturated electrodes. The partially wet positive electrode (40% saturation) obtained more cycles than the electrode with 100% saturation before the discharge capacity dropped below the cutoff point. However, the electrode with 40% saturation had a low average charging efficiency of 88.76%, whereas the fully saturated electrode obtained 98.96% charging efficiency. Moreover, the fully wet positive electrode had the lowest overpotential during cycling (1.26-1.39 V). The measured electrochemically active surface areas showed that even 40% saturation could sufficiently wet the positive electrode surface and obtain a double-layer capacitance (18.12 mF) similar to that with 100% saturation (20.4 mF). Furthermore, a considerable increase in O2 concentration at wetted surface areas was observed for the electrolyte saturation of less than 60% due to the significantly higher O2 diffusivity in the gas phase.

Hexagonal Prism-Shaped AIE-Active MOFs as Coreactant-Free Electrochemiluminescence Luminophores Coupled with Hollow Cu2-xO@Pd Heterostructures as Efficient Quenching Probes for Sensitive Biosensing.

For most self-luminous metal-organic framework (MOF)-involved electrochemiluminescence (ECL) systems, the integration of exogenous coreactants is indispensable to promote ECL efficiency. However, the introduction of a coreactant into an electrolyte would result in poor stability, thereby inevitably affecting analytical accuracy. Herein, by employing aggregation-induced emission luminogens as ligands, we first synthesized one hexagonal prism-shaped MOF that displays robust and steady ECL signal without an exogenous coreactant. Furthermore, adenosine triphosphate (ATP), as the target analyte, can be fixed on the electrode surface directly owing to the strong coordination between Zr4+ and phosphate groups. According to the ECL resonance energy transfer effect, hollow Cu2-xO@Pd heterostructures are conveniently prepared and act as efficient quenching probes. Remarkably, the resultant urchin-like hollow structure could provide more active sites to anchor ATP aptamers, thus enhancing the ECL quenching efficiency. In this manner, an elaborate coreactant-free ECL system was developed to detect ATP, which demonstrates a remarkable detection limit of 0.17 nM, as well as excellent stability and reproducibility. The present work offers significant enlightenment for the further evolution of advanced ECL systems integrated with MOF-based luminophores.

Electroanalytical Probing of Triphasic Hydrogen Storage and Transport in Films of Nanoparticulate Polymer of Intrinsic Microporosity (PIM-1)

AbstractPreliminary experiments are reported to show quantitatively that hydrogen gas can be stored under triphasic conditions in wet nanoparticulate polymer of intrinsic microporosity (PIM-1) applied as a film to a platinum disk electrode surface. Based on chronoamperometric data, it is shown that the resulting triphasic interface is able to store hydrogen gas at apparent concentrations higher (3 orders of magnitude increase for an approx. 15 μm thick film with typically capp,hydrogen = 80 mM; Dapp,hydrogen = 1.2 × 10–11 m2s−1) than the known solubility of hydrogen gas in aqueous electrolyte (chydrogen = 0.08 mM; Dhydrogen = 5.0 × 10–9 m2s−1) at room temperature. Due to film roughness/heterogeneity, the apparent hydrogen concentration can only be estimated, but it increases with film thickness. At the same time the apparent diffusion coefficient is lowered considerably due to the molecularly rigid/glassy polymer host. The resulting modified electrode is investigated/proposed for energy storage applications with different amounts of PIM-1 nanoparticle deposits attached to the platinum surface. Graphical Abstract

Gold–Graphene Quantum Dot Hybrid Nanoparticle for Smart Diagnostics of Prostate Cancer

Prostate cancer is one of the most prevalent cancers afflicting men worldwide, often detected at advanced stages, leading to increased mortality rates. Addressing this challenge, we present an innovative approach employing electrochemical biosensing for early-stage prostate cancer detection. This study used Indium–Tin Oxide (ITO) as a substrate and a deposited gold–graphene quantum dot (Au–GQD) nanohybrid to establish electrochemical sensing platforms for DNA-hybridization assays. A capturing DNA probe, PCA3, was covalently immobilized on the surface of the Au–GQDs and deposited electrochemically onto the ITO electrode surface. The Au–GQDs enabled the capturing of the target PCA3 biomarker probe. The sensor achieved a limit of detection (LoD) of up to 211 fM and presented a linear detection range spanning 1 µM to 100 fM. A rapid 5-min response time was also achieved. The tested shelf life of the pre-immobilized sensor was approximately 19 ± 1 days, with pronounced selectivity for its intended target amidst various interferants. The sensing device has the potential to revolutionize prostate cancer management by facilitating early-stage detection and screening with enhanced treatment efficacy.

Enhancing Li+ Transportation at Graphite‐Low Concentration Electrolyte Interface Via Interphase Modulation of LiNO3 and Vinylene Carbonate

ABSTRACTThe solvent‐rich solvent sheath in low‐concentration electrolytes (LCEs) not only results in high desolvation energy of Li+, but also forms organic‐rich solid electrolyte interface film (SEI) with poor Li+ conductivity, which hinders Li+ transport at the electrode‐electrolyte interface and greatly limits the application of LCEs. Here, the electrochemical performance of the LCEs is enhanced by dual interfacial modification with LiNO3 and vinylene carbonate (VC) additives. Results show that LiNO3 is preferentially reduced at about 1.65 V to form an inorganic‐rich but incomplete SEI inner layer. The formation of Li3N and LiNxOy inorganic components helps to achieve rapid Li+ transport in the SEI film, and the bare electrode surface caused by the incomplete SEI inner layer provides a place for the subsequent decomposition of VC. Then, at a lower potential of about 0.73 V, VC is reduced to generate the poly(VC)‐rich SEI outer layer, which provides lithium‐philic sites and greatly weakens the interaction between Li+ and ethylene carbonate (EC). The interaction modulates the Li+ solvation structure at the interface and reduces the desolvation energy of Li+. This ingenious design of the bilayer SEI film greatly enhances Li+ transport and inhibits the decomposition of traditional carbonate solvents and the swelling of graphite. As a result, the electrochemical performance of the battery using 0.5 M LiPF6 EC/diethyl carbonate (DEC) + 0.012 M LiNO3 + 0.5 vt% VC is improved to a higher level than the one using 1.0 M LiPF6 EC/DEC electrolyte. This research expands the design strategy and promising applications of LCEs by constructing a favorable SEI to enhance Li+ transport at the electrode‐electrolyte interface.

A Dual Effect Additive Modified Electrolyte Strategy to Improve the Electrochemical Performance of Zinc-Based Prussian Blue Analogs Energy Storage Device.

Prussian blue analogs (PBA) exhibit excellent potential for energy storage due to their unique three-dimensional open framework and abundant redox active sites. However, the dissolution of transition metal ions in water can compromise the structural integrity of PBAs, leading to significant issues such as low cycle life and capacity decay. To address these challenges, we proposed a dual-effect additive-modified electrolyte method to alleviate such issues, introducing sodium ferrocyanide (Na4Fe(CN)6) into aqueous alkaline electrolytes. It could not only capture Zn2+ dissolved on the surface of Na1.86Zn1.46[Fe(CN)6]0.87 (ZnHCF) electrode material during the cycling process but also conduct redox reactions on the electrode surface to provide additional capacitance. Through experiments and molecular simulation calculations, it showed that Na4Fe(CN)6 can restrict the movement of Zn dissolution into the electrolyte on the electrode surface. Based on this, an asymmetric supercapacitor based on ZnHCF//activated carbon was assembled with a modified electrolyte. The assembled supercapacitor displayed a specific capacitance of 1,329.65 mF cm-2, a power density of 2,900 mW cm-2, and an energy density of 388.28 mW h cm-2. This study provides a new idea for the design and construction of stable and efficient PBA energy storage materials by inhibiting the leaching of transition metals in PBA.

A novel label-free impedance biosensor for KRAS G12C mutations detection based on PET-RAFT and ROP synergistic signal amplification

The KRAS G12C mutations, as crucial biomarkers, are closely associated with non-small cell lung cancer. Here, a novel label-free electrochemical biosensor with synergistic signal amplification of photocell energy transfer-reversible addition fragmentation chain transfer (PET-RAFT) and ring-opening polymerization (ROP) was developed for the first time for sensitive detection of KRAS G12C mutations. Specifically, hairpin DNA (hDNA), which act as biomolecular probe, was self-assembled on Au electrode surface by Au-S bond. 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid (CDTPA), the chain transfer agent of PET-RAFT reaction, was then attached to hDNA via amide bond. After that, the target DNA (tDNA) was captured on the electrode surface by complementary base pairing with hDNA. Subsequently, large numbers of electro-active monomers N-acryloxysuccinimide (NAS) were successfully grafted to the electrode surface via PET-RAFT reaction, which provided plenty of junction sites for doxorubicin-polycaprolactone (Dox-PCL) synthesized by ROP. Finally, the Dox-PCL was connected to the electrode surface by ester bond, significantly amplifying the electrochemical signal. Under optimized conditions, the biosensor has a wide linear detection range of 0.1 pM to 1 μM, with a detection limit of 86.9 fM. Attribute to its high sensitivity, specificity, reproducibility and stability, this biosensor possesses considerable potential in early diagnosis of disease and biomedical research.

Surface Fluorination Mediated Electro-Oxidative Degradation of HFPO-DA on Boron-Doped Diamond Electrode

Heptafluoropropylene oxide dimer acid (HFPO-DA), as an alternative to perfluorooctanoic acid (PFOA), has been shown to pose similar environmental and health risks as other perfluorinated compounds. The electrochemical-based advanced oxidation processes are promising techniques for the treatment of perfluorinated compounds, and the boron-doped diamond (BDD) anode could degrade HFPO-DA under mild conditions. However, the roles of radicals in the degradation and how to overcome the steric hindrance of the –CF3 branch on the carboxyl group were not yet clear. In this study, we investigated the degradation mechanism of HFPO-DA on the BDD anode. Instead of other non-active anodes (PbO2 and SnO2 electrodes), HFPO-DA can be degradable on the BDD electrode with a rate constant logarithmic correlation to the applied current density. The hydroxyl radical (•OH) was one of the key factors in the degradation of HFPO-DA, accounting for almost 89% of the significant effect, and the direct electron transfer was the rate-limiting step in the degradation reaction. Physicochemical characterization including field emission scanning electron microscope (FE-SEM), X-ray photo-electron spectroscopy (XPS), water contact angle, and electrochemical property indicated that the BDD electrode was fluorinated after electrolysis, the electrode surface became more hydrophobic due to the bonding of –CxFy, leading to a decrease in the electrochemically active area. Moreover, degradation products (pentafluoropropionic acid, trifluoroacetic acid, and fluorine ion) were detected and the mass balance of carbon and fluorine was calculated during the degradation. Therefore, a degradation mechanism for HFPO-DA was proposed, which involved direct electron transfer, decarboxylation, radical reaction, decarboxylation, and decarboxylation. The de–CF3 step initiated the fluorination of the BDD electrode, which was initiated by the defluorination process. This study contributes to the understanding of the electro-oxidative degradation of perfluoroalkyl ether carboxylic acids and provides guidance for the application of electrochemical advanced oxidation processes.