Nanostructured Electrodes Research Articles

Overlooked competition and promotion effects in electrochemical oxidation of humic acid and ammonia in landfill leachate

Electrochemical oxidation (EO) can effectively reduce the degree of humification and toxicity of landfill leachate by generating highly active oxidative species in situ. However, the selective and competitive oxidation of humic acid (HA) and ammonia (NH4+) and the role of different oxidative species during the EO process in complex aqueous conditions remain unclear. In this study, a nanostructured tin-antimony electrode (Ti/Sb-SnO2 NFs) was prepared and compared with three types of commercial electrodes (Ti/Ir-RuO2, Ti4O7, Ti/Sb-SnO2) in terms of electrochemical properties and electrocatalytic oxidation of HA and NH4+. The de-humification capacity, interactive effects of HA and NH4+ on each other's oxidation by different oxidative species, as well as the related oxidation byproducts were investigated. The differences in pollutant electrooxidation among the different electrodes were found to be insignificant. The presence of HA was found to be detrimental to NH4+ degradation while reducing the N2 conversion rate. Interestingly, NH4+ initially inhibited the degradation rates of HA while promoted the degradation and reduced the accumulation of organic chlorine during the later EO process. A proposed mechanism accounts for both competitive and promotional effects for simultaneous HA and NH4+ oxidation during the EO process.

Nickel Disulfide (NiS2): A Sustainable Low‐Cost Electrode Material for High‐Performance Supercapacitors

In the family of transition metal sulfides, nickel disulfide (NiS2) received significant attention in the recent past, particularly as an electrode‐active material for supercapacitors due to its high specific capacitance, high power density, long cyclic stability, and low cost. A detailed overview on the supercapacitor applications of NiS2 is lacking in the literature. In this review article, the unique features of NiS2 in terms of its various methods of synthesis, characterizations, and electrochemical performance evaluations are described. This review provides an in‐depth understanding on the unique properties of ultrathin nanostructured NiS2 such as structural properties, electronic properties, optical properties, and so on. Later, the various methods of synthesis including hydrothermal method, solvothermal method, solvent‐free approach, and so on are reviewed. Further, the strategies are discussed to improve the electrochemical performance of NiS2 by preparing hybrids or nanocomposites with other types of electrode‐active materials. The influence of electrode nanostructure and surface morphology on the charge storage is discussed with the help of specific examples. Furthermore, the potential challenges and future perspectives of NiS2 for commercial supercapacitors are examined. This review proclaims the development of novel approaches and strategies for the effective utilization of NiS2‐based electrodes for high‐performance low‐cost supercapacitors.

Zr/Ni metal oxide nanostructures: Electrochemical exploration and urea oxidation catalysts

Metal-organic framework (MOF) derived metal oxide nanostructures hold immense promise as electrodes for energy storage/conversion applications, notably in supercapacitors and urea oxidation. This study explores into optimizing such nanostructures, specifically focusing on a Zr/Ni ratio of 1:1, which has exhibited favorable electrochemical and catalytic performance. Employing thorough characterization methods, including PXRD analysis, we verified the successful synthesis of a ZrO2/NiO binary phase (i.e. Zr/Ni) nanostructure via the MOF-derived approach, showcasing its versatility as a catalyst across diverse energy conversion domains. The Zr/Ni nanostructure electrode displayed noteworthy characteristics, boasting a capacity of 432 C/g alongside exceptional cycling stability of 99%, reflecting battery-like electrochemical behavior. Furthermore, in an asymmetric device setup (Zr/Ni//AC), it achieved a notable potential of up to 1.4 V with an impressive power density of 1044.56 W/kg. Additionally, the Zr/Ni nanostructure demonstrated efficient electrocatalytic activity in urea oxidation, evidenced by a maximum current density of 60 mA/cm2. This underscores its viability as a preferred catalyst in energy conversion applications, signaling opportunities for further exploration and advancement in this dynamic field.

Raman Monitoring of the Electro-Optical Synergy-Induced Enhancements in Carbon-Bromine Bond Cleavage, Reaction Rate, and Product Selectivity of p-Bromothiophenol.

Electro-optical synergy has recently been targeted to improve the separation of hot carriers and thereby further improve the efficiency of plasmon-mediated chemical reactions (PMCRs). However, the electro-optical synergy in PMCRs needs to be more deeply understood, and its contribution to bond dissociation and product selectivity needs to be clarified. Herein, the electro-optical synergy in plasmon-mediated reduction of p-bromothiophenol (PBTP) was studied on a plasmonic nanostructured silver electrode using in situ Raman spectroscopy and theoretical calculations. It was found that the electro-optical synergy-induced enhancements in the cleavage of carbon-bromine bonds, reaction rate, and product selectivity (4,4'-biphenyl dithiol vs thiophenol) were largely affected by the applied bias, laser wavelength, and laser power. The theoretical simulation further clarified that the strong electro-optical synergy is attributed to the matching of energy band diagrams of the plasmonic silver with those of the adsorbed PBTP molecules. A deep understanding of the electro-optical synergy in PBTP reduction and the clarification of the mechanism will be highly beneficial for the development of other highly efficient PMCRs.

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions.

Bubble dynamics significantly impact mass transfer and energy conversion in electrochemical gas evolution reactions. Micro-/nanostructured surfaces with extreme wettability have been employed as gas-evolving electrodes to promote bubble departure and decrease the bubble-induced overpotential. However, effects of the electrodes' wickability on the electrochemical reaction performances remain elusive. In this work, hydrogen evolution reaction (HER) performances are experimentally investigated using micropillar array electrodes with varying interpillar spacings, and effects of the electrodes' wettability, wickability as well as bubble adhesion are discussed. A deep learning-based object detection model was used to obtain bubble counts and bubble departure size distributions. We show that microstructures on the electrode have little effect on the total bubble counts and bubble size distribution characteristics at low current densities. At high current densities, however, micropillar array electrodes have much higher total bubble counts and smaller bubble departure sizes compared with the flat electrode. We also demonstrate that surface wettability is a critical factor influencing HER performances under low current densities, where bubbles exist in an isolated regime. Under high current densities, where bubbles are in an interacting regime, the wickability of the micropillar array electrodes emerges as a determining factor. This work elucidates the roles of surface wettability and wickability on enhancing electrochemical performances, providing guidelines for the optimal design of micro-/nanostructured electrodes in various gas evolution reactions.

A micro-electrochemical sensor based on a nanostructured carbon paste electrode as an original tool for selective detection of ultra-traces of 17α –ethinylestradiol in environmental water samples and in biologic fluids

A new electrochemical micro-sensor has been designed for the sensitive detection of ultra-traces of 17α – ethinylestradiol (EE2). A carbon paste cavity micro-electrode modified by carbon black nanoparticles (GC-nCB)-µCPE was used with an electrochemical preconcentration (EP) step of EE2 on (GC-nCB)-µCPE at 0.0 V during 300 s in a 0.01 mol.L-1 phosphate buffer solution (pH = 7.4) before voltammetric determination. The results demonstrate that two line calibrations were obtained in the concentration ranges of 0.005 to 0.2 μmol.L-1 and 0.2 to 1 μmol.L-1. The detection and quantification limits are estimated at 1.4 nmol.L-1 and 4.9 nmol.L-1, respectively. Moreover, a high sensitivity of 4.16 µA.mol−1.L and good selectivity for the quantification of EE2 in the presence of different interfering organic and inorganic compounds were observed. Based on the results (satisfactory recovery (less than 3.5 %) and relationship standard deviation (less than 2.5 %)),the designed micro-sensor can be successfully applied to the analysis of EE2 in environmental water samples and in biologic fluids.The modified microsensor presented an efficient and inexpensive tool for the quantification of EE2.

Enhanced Supercapacitive Performance in Catalyst‐Free Binary Composite SnO2–RuO2 Nanostructured Thin Films for Symmetric Supercapacitor Device

In the present work, thin film electrodes of ruthenium oxide (RuO2), tin oxide (SnO2), and their composite SnO2–RuO2 are deposited on 304 stainless steel substrates using pulsed laser deposition (PLD). These nanostructured electrodes are then evaluated for their suitability in electrochemical energy storage applications. A symmetric supercapacitor device (SSD) is constructed using the SnO2–RuO2 composite electrodes. Compared to individual SnO2 and RuO2 electrodes, the composite electrodes exhibit enhanced specific capacitance and cycle life. This improvement is attributed to modifications in surface morphology and electronic properties. This modified surface morphology of the composite electrode, creates favourable conditions for electrolyte interaction and ion transport, ultimately contributing to the observed increase in specific capacitance. Specifically, the composite electrode demonstrates a specific capacitance of 170.2 Fg−1 at a current density of 0.1 mA cm−2, outperforming SnO2 (37.4 Fg−1). The SnO2–RuO2//SnO2–RuO2 SSD exhibites a specific capacitance of 70.0 Fg−1 at a current density of 0.1 mA cm−2, coupled with energy density and power density values of 19.05 Wh kg−1 and 645 W kg−1, respectively, within a voltage window of 1.4 V. The SSD displays an impressive capacitive retention of 81.27% over 10 000 cycles, indicating its potential for practical energy storage applications.

Effective photoabsorption and band-structural engineering in CuxO/NiO interfacial photosensor for improved ultraviolet response

Energy bands modulations in thin films heterostructure has offered exceptional leads towards the development of photosensing material. In this work, nanostructured metal oxides interfacial electrode structure has been employed to fabricate a highly sensitive ultraviolet (UV) sensor with high responsivity and detectivity. A unique, simple and cost-effective electrodeposition approach was adopted for the growth of the film samples. The interfacial structural effect and optical energy band modulations on the photo-electronic structure and UV detector performance of the structure have been examined. The films had fair transmissions of the visible light spectrum with CuxO dominance in the resulting bilayer structure and a high absorption peak in the ultraviolet (UV) region. The energy band gap redshifted towards the bilayer structure from 3.74 to 2.67 eV. Charge carriers trapping through surface recombination has been found to reduce from the assistance of ohmic contact formation of the heterostructure. The bilayer film-based photodetector demonstrated enhanced performance with photodetectivity (1.6⨯1011 Jones at 0.068 mWcm−2 power density), attributable to the existence of lower recombination state in the structure, according to the UV sensing study. The study showed that tailoring dissimilar metal oxide semiconducting films to the bilayer (CuxO/NiO) structure can provide excellent UV photodetector performance over single-layer of NiO and CuxO.

Enhanced electrochemical properties of PbO-rGO nanocomposite prepared by wet chemical method for supercapacitor applications

The supercapacitor is a future energy device because of its higher power density and outstanding cyclic stability with a quick charge and discharge process. Supercapacitors have a lower energy density than regular batteries. The electrochemical characteristic of supercapacitors is strongly depend on the electrode materials. The nanostructured electrode materials continue to be a main focus of supercapacitor research. The considered electrode materials, such as, Lead oxide (PbO) and reduced graphene oxide (rGO) have been widely used in supercapacitors due to their fascinating physicochemical properties. The PbrG was synthesized using the simple and cost-effective ultrasonic-assisted solution method. The prepared PbO and PbrG were examined in XRD, TEM and XPS. The XRD studies confirmed the presence of crystal structure in PbO and PbrG. The TEM images reveal the embellishment of PbO on the rGO sheets. The PbrG showed a higher specific capacitance (448 F/g) compared to PbO NANO (177 F/g) with better cycling stability until 5000 cycles and exhibited excellent conductivity due to the presence of rGO. These properties of PbrG ensures that this electrode material play a beneficial role in the energy storage applications.

Cellulose‐based smart materials: Novel synthesis techniques, properties, and applications in energy storage and conversion devices

AbstractThere has been a significant scope toward the cutting‐edge investigations in hierarchical carbon nanostructured electrodes originating from cellulosic materials, such as cellulose nanofibers, available from natural cellulose and bacterial cellulose. Elements of energy storage systems (ESSs) are typically established upon inorganic/metal mixtures, carbonaceous implications, and petroleum‐derived hydrocarbon chemicals. However, these conventional substances may need help fulfilling the ever‐increasing needs of ESSs. Nanocellulose has grown significantly as an impressive 1D element due to its natural availability, eco‐friendliness, recyclability, structural identity, simple transformation, and dimensional durability. Here, in this review article, we have discussed the role and overview of cellulose‐based hydrogels in ESSs. Additionally, the extraction sources and solvents used for dissolution have been discussed in detail. Finally, the properties (such as self‐healing, transparency, strength and swelling behavior), and applications (such as flexible batteries, fuel cells, solar cells, flexible supercapacitors and carbon‐based derived from cellulose) in energy storage devices and conclusion with existing challenges have been updated with recent findings.

Electrospun nickel cobalt phosphide/carbon nanofibers as high-performance electrodes for supercapacitors

Nickel cobalt phosphide/carbon nanofibers (NiCoP/C) with an average diameter of approximate 200 nm are prepared by electrospinning combined with calcinations. Carbon nanofibers with an average pore size of 10.77 nm as conductive skeletons support the dispersed NiCoP nanoparticles with the size ranging from 20 to 80 nm, providing abundant reactive sites and facilitating the electrochemical reactions. The specific capacitance of NiCoP/C reaches 478 F g−1 at 2 A g−1 in a 3 M KOH electrolyte, showing superior electrochemical properties compared to its counterparts. After 5000 charge/discharge cycles at 10 A g−1, 99.99 % of initial specific capacitance is retained. In addition, an asymmetric supercapacitor assembled using NiCoP/C as positive electrode and activated carbon as negative electrode exhibits an energy density of 16.72 Wh kg−1 at a high-power density of 7250 W kg−1. Furthermore, the capacitance loss of the supercapacitor is only 0.04 % after 5000 cycles at 10 A g−1, which is mainly attributed to the enhanced stability of NiCoP nanoparticles owing to the assistance of carbon nanofibers as the skeleton. The synergistic effects of NiCoP nanoparticles and carbon nanofibers result in the boosted electrochemical performances. This study demonstrates the potential application of carbon nanofibers as conductive skeletons for nanostructured electrodes.

Low-cost inkjet-printed nanostructured biosensor based on CRISPR/Cas12a system for pathogen detection

The escalating global incidence of infectious diseases caused by pathogenic bacteria, especially in developing countries, emphasises the urgent need for rapid and portable pathogen detection devices. This study introduces a sensitive and specific electrochemical biosensing platform utilising cost-effective electrodes fabricated by inkjet-printing gold and silver nanoparticles on a plastic substrate. The biosensor exploits the CRISPR/Cas12a system for detecting a specific DNA sequence selected from the genome of the target pathogen. Upon detection, the trans-activity of Cas12a/gRNA is triggered, leading to the cleavage of rationally designed single-strand DNA reporters (linear and hairpin) labelled with methylene blue (ssDNA-MB) and bound to the electrode surface. In principle, this sensing mechanism can be adapted to any bacterium by choosing a proper guide RNA to target a specific sequence of its DNA. The biosensor's performance was assessed for two representative pathogens (a Gram-negative, Escherichia coli, and a Gram-positive, Staphylococcus aureus), and results obtained with inkjet-printed gold electrodes were compared with those obtained by commercial screen-printed gold electrodes. Our results show that the use of inkjet-printed nanostructured gold electrodes, which provide a large surface area, in combination with the use of hairpin reporters containing a poly-T loop can increase the sensitivity of the assay corresponding to a signal variation of 86%. DNA targets amplified from various clinically isolated bacteria, have been tested and demonstrate the potential of the proposed platform for point-of-need applications.

Pengaruh Konsentrasi Oksida Logam CuO Sebagai Superkapasitor Berbasis Karbon Aktif

Supercapacitors are promising energy storage devices in future energy technology. In this research, the primary and applied aspects of supercapacitors are developed. Various techniques have been developed specifically to estimate specific capacitances. Various attempts have been made in the literature to increase the specific capacitance value of the electrode materials. Electrode materials with unique structural and electrochemical properties, such as high capacity and cyclic stability, exhibit good supercapacitor performance. Many new electrode materials have been developed to play an essential role in capacitance behavior. This research focuses on the highly efficient application of nanostructured electrode materials such as nanoporous carbon and metal oxide CuO for supercapacitors. Nanopore carbon is made from coconut shell, which is synthesized using a simple heating method. Next, carbon nanopore and CuO nanoparticle composites were carried out with composition variations of 0.5,10,15, and 20% of the total weight. The results of cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge tests, maximum results were obtained on a composition of 5% CuO nanoparticles with a capacitance of 280 F/gr and a conductivity of 1.14 X 10-2 S/cm. This result is due to an increase in the surface area between the pore surfaces, so more ions are trapped, causing the filling process to take place quickly.

Nanostructured boron-doped diamond electrodes for two-electron water oxidation to produce hydrogen peroxide

Boron-doped diamond (BDD) electrodes have been widely used in water treatment, e.g., degradation of antibiotics and pigments for water purification. Hydrogen peroxide production by two-electron electrochemical oxidation of water is a green and attractive method that has the potential to replace the conventional anthraquinone autoxidation (AO) process. In this study, BDD films were prepared on single-crystal silicon wafers by using hot-filament chemical vapor deposition (HFCVD) technique. Then, dense tubular nanostructure (nanotubes) arrays were prepared on the BDD films employing inductively coupled plasma (ICP) etching. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) proved the formation of oxygen-terminated nanostructures, which was ascribed to the oxygen plasma and the self-masking. The length of diamond nanotubes as well as the root diameter increased gradually and non-linearly with the increase of etching time. It was indicated by cyclic voltammetry (CV) analysis that the effective active area of the electrodes increased after etching, and variations of resulting reaction performance were observed. The oxygen-terminated and nanostructured BDD electrode obtained by etching with the optimized parameters features better electrocatalytic performance, with reduced oxidation potential and 46.8 % higher Faraday Efficiency (FE) for hydrogen peroxide production, compared to the original BDD sample. Therefore, the manufacturing of nanostructures is an effective method to improve the efficiency of BDD water oxidation for the production of hydrogen peroxide.

Investigation of the Efficacy of a Listeria monocytogenes Biosensor Using Chicken Broth Samples.

Foodborne pathogens are microbes present in food that cause serious illness when the contaminated food is consumed. Among these pathogens, Listeria monocytogenes is one of the most serious bacterial pathogens, and causes severe illness. The techniques currently used for L. monocytogenes detection are based on common molecular biology tools that are not easy to implement for field use in food production and distribution facilities. This work focuses on the efficacy of an electrochemical biosensor in detecting L. monocytogenes in chicken broth. The sensor is based on a nanostructured electrode modified with a bacteriophage as a bioreceptor which selectively detects L. monocytogenes using electrochemical impedance spectroscopy. The biosensing platform was able to reach a limit of detection of 55 CFU/mL in 1× PBS buffer and 10 CFU/mL in 1% diluted chicken broth. The biosensor demonstrated 83-98% recovery rates in buffer and 87-96% in chicken broth.

Development of Nanostructured Lanthanum Strontium Cobalt Ferrite/Gadolinian-Doped Ceria Composite Electrodes of Solid Oxide Cells Formed by In Situ Polarization.

In the development of nanoscale oxygen electrodes of high-temperature solid oxide cells (SOCs), the interface formed between the nanoelectrode particles and the electrolyte or electrolyte scaffolds is the most critical. In this work, a new synthesis technique for the fabrication of nanostructured electrodes via in situ electrochemical polarization treatment is reported. The lanthanum strontium cobalt ferrite (LSCF) precursor solution is infiltrated into a gadolinia-doped ceria (GDC) scaffold presintered on a yttria-stabilized zirconia (YSZ) electrolyte, followed by in situ polarization current treatment at SOC operation temperatures. Electrode ohmic and polarization resistances decrease with an increase in the polarization current treatment. Detailed microstructure analysis indicates the formation of a convex-shaped interface between the LSCF nanoparticles (NPs) and the GDC scaffold, very different from the flat contact between LSCF and GDC observed after heating at 800 °C with no polarization current treatment. The embedded LSCF NPs on the GDC scaffold contribute to the superior stability under both fuel cell and electrolysis operation conditions at 750 °C and a high peak power density of 1.58 W cm-2 at 750 °C. This work highlights a novel and facile route to in situ construct a stable and high-performing nanostructured electrode for SOCs.

Enhancement of Performance and Sulfur Tolerance of Ceria-Based Fuel Electrodes in Low Temperature SOFC

The trend of operating the solid oxide fuel cell at significantly lower operation temperatures enables the application of electrodes with finer microstructure or even nanostructured electrodes with increased active surface and enhanced performance. To maintain the high performance in hydrocarbon fuels commonly impurified with sulfur compounds, a required sulfur tolerance has to be maintained. In this study we compare performance and H2S-poisoning of four ceria-based electrodes: conventional Ni/Ce0.9Gd0.1O2−δ cermets and sub-μm scaled Ce0.8Gd0.2O2−δ -electrodes with and without infiltrated nickel. Symmetrical cells were operated in a hydrogen/steam/nitrogen gas mixture with and without minor amounts of H2S at 600 °C. The performance is analyzed by electrochemical impedance spectroscopy. The distribution of relaxation times is applied to deconvolute the electrochemical processes followed by a complex nonlinear least square fit to quantify the loss processes and the impact of sulfur. Whereas two different Ni/Ce0.9Gd0.1O2−δ cermet electrodes exhibit polarization resistances at 600 °C without/with 0.1 ppm H2S of 2.89/5.56 Ωcm2 and 2.15/2.75 Ωcm2, the single phase Ce0.8Gd0.2O2−δ electrode reaches 0.98/2.37 Ωcm2. With an infiltration of Ni-nitrate forming nickel nanoparticles on the gadolinia-doped ceria-surfaces, the ASR could be drastically reduced to 0.32/0.37 Ωcm2.

Influence of nanocolumnar electrode geometry on electrochemical sensor performance

The concentration of glucose in sweat recently has been measured with high sensitivity, selectivity, and reproducibility by nanostructured NiO electrodes manufactured by the glancing angle deposition (GLAD) technique. The GLAD technique allows electrode morphological properties such as porosity and film thickness to be tightly controlled, providing ample opportunity to enhance the sensor performance. Currently, the selection of optimal GLAD parameters is determined experimentally by trial and error, at high costs in time and resources. Numerical simulation allows the effects of various parameters on sensor performance to be investigated at a much lower cost compared to experimental studies. In this work, a 2D reaction–diffusion model for the surface-catalyzed reactions in the nanostructured GLAD electrodes is developed, which are then solved using the finite element method. Parametric studies on the nanocolumn thickness and nanocolumn separation of the GLAD structures are then conducted to optimize GLAD-based electrode structures with different adsorption and catalytic rates. This research offers new guidance for rapidly designing highly effective sensors with higher sensitivity and lower limits of detection.

Ultrasensitive Aptasensing Platform for the Detection of β-Amyloid-42 Peptide Based on MOF Containing Bimetallic Porphyrin Graphene Oxide and Gold Nanoparticles.

The prompt detection of diseases hinges on the accessibility and the capability to identify relevant biomarkers. The integration of aptamers and the incorporation of nanomaterials into signal transducers have not only expedited but also enhanced the development of nanoaptasensors, enabling heightened sensitivity and selectivity. Here, the bimetallic nickel-cobalt-porphyrin metal-organic framework ((Ni + Cu)TPyP MOF) is regarded as an electron mediator, immobilization platform for an Alzheimer aptamer and to increase the electrochemical signal for the detection of the main biomarker of Alzheimer's disease (AD), amyloid β (Aβ-42). Furthermore, the ((Ni + Cu)TPyP MOF) was combined with reduced graphene oxide (rGO) and gold nanoparticles (AuNPs), on a gold electrode (GE) to provide an efficient interface for immobilizing aptamer strands. Concurrently, the incorporation of rGO and AuNPs imparts enhanced electrical conductivity and efficacious catalytic activity, establishing them as adept electrochemical indicators. Owing to the superior excellent electrical conductivity of rGO and AuNPs, coupled with the presence of ample mesoporous channels and numerous Ni and Cu metal sites within (Ni + Cu)TPyP MOF, this nanostructure with abundant functional groups is proficient in immobilizing a substantial quantity of aptamer. These interactions are achieved through robust π-π stacking and electrostatic interactions, alongside the high affinity between the thiol group of the aptamer and AuNPs concurrently. The as-prepared ternary (Au@(Ni + Cu)TPyP MOF/rGO) nanostructure electrode exhibited an enhancement in its electrochemically active surface area of about 7 times, compared with the bare electrode and the Aβ-42 redox process is highly accelerated, so the peak currents are significantly higher than those obtained with bare GE substrate. Under the optimized conditions, the designed aptasensor had the quantitative detection of Aβ-42 with a low detection limit of 48.6 fg mL-1 within the linear range of 0.05 pg mL-1 to 5 ng mL-1 by differential pulse voltammetry (DPV), accompanied by precise reproducibility, satisfactory stability (95.6% of the initial activity after 10 days), and minimal impact of interfering agents. Recorded results in human blood plasma demonstrated the high efficacy of porphyrin MOF system sensing even in the clinical matrix. The great performance of this aptasensor indicates that our new design of Au@(Ni + Cu)TPyP MOF/rGO nanostructure provides more opportunities for the detection of chemical signals in early diagnosis of Alzheimer's disease.

Quantum control of exciton wave functions in 2D semiconductors.

Excitons-bound electron-hole pairs-play a central role in light-matter interaction phenomena and are crucial for wide-ranging applications from light harvesting and generation to quantum information processing. A long-standing challenge in solid-state optics has been to achieve precise and scalable control over excitonic motion. We present a technique using nanostructured gate electrodes to create tailored potential landscapes for excitons in 2D semiconductors, enabling in situ wave function shaping at the nanoscale. Our approach forms electrostatic traps for excitons in various geometries, such as quantum dots, rings, and arrays thereof. We show independent spectral tuning of spatially separated quantum dots, achieving degeneracy despite material disorder. Owing to the strong light-matter coupling of excitons in 2D semiconductors, we observe unambiguous signatures of confined exciton wave functions in optical reflection and photoluminescence measurements. This work unlocks possibilities for engineering exciton dynamics and interactions at the nanometer scale, with implications for optoelectronic devices, topological photonics, and quantum nonlinear optics.