Noe. T. Alvarez

Aryl diazonium electrografting enables robust covalent bonding of organic molecules to metallic and carbon-based substrates. Despite its widespread use, the influence of specific functional groups on the electrode–electrolyte interfacial response remains insufficiently understood. Once grafted, these molecules alter the electronic environment of the substrate, affecting interfacial stability, charge transfer, and interactions with the surrounding medium. On conductive metals, organic layers have often been reported to increase electron transfer resistance, and forming stable monolayers remains challenging due to the high reactivity of N≡N⁺ precursors. Here, we combine quantum chemistry calculations with impedance spectroscopy to investigate the interfacial behavior of 4-aminophenyl and 4-nitrobenzene groups grafted onto Au surfaces. Experimentally, 4-aminophenyl grafting decreases charge transfer resistance, while 4 nitrobenzene increases it. Theoretical analysis supports these observations by revealing differences in charge distribution at the interface, adsorption geometries, and bonding strength, clarifying the relative stability and electronic influence of each linker. Conductance is also evaluated in multiple electrode configurations, including systems where carbon nanotubes are linked to gold substrates. This combined theoretical–experimental approach demonstrates how atomistic analysis could guide the design of improved conductive interfaces and highlights the importance of quantum chemical methods for tailoring molecular anchoring and optimizing nanoscale electronic device performance.

Nano- and micro-particulate forms of lead represent a persistent threat to drinking water safety, yet they cannot be detected by electrochemical methods. This review highlights recent advances and the remaining challenges in the field.

Orthophosphate is a common inhibitor used to prevent dissolved lead leaching from the pipes into drinking water. Lead phosphate scales can aggregate over time, detach, and cause severe water contamination. Accurate quantification of Pb requires rigorous acid treatment to obtain a sample that is free of insoluble particles. This paper describes the use of membrane electrolysis for the reagent-free dissolution of real lead phosphate scales collected from corroded pipes. The method allows for the in-situ generation of acidic environment, which in the combination with anodic stripping voltammetry provides a powerful tool for the accurate and reagentless quantification of Pb in contaminated water samples. The integration of the sample preparation and voltammetric detection in a single unit allows for the autonomous operation with minimal attention, making this method suitable for the development of on-site quantification devices. This technique has been successfully applied to electrochemically dissolve and quantify highly insoluble lead phosphate in tap water, allowing the complete dissolution and accurate voltammetric quantification of particulate Pb without any external acid addition for treatment of the tap water samples. The results were in a good agreement with inductively coupled plasma-mass spectrometry measurements, showing ≤14% relative error.

As energy storage devices, electrochemical double-layer capacitors (EDLCs) are a potential alternative to traditional batteries owing to their higher charge-discharge capability, higher power density, and longer life span; however, EDLCs typically lack energy density. Carbon nanotubes (CNTs), which have a high surface area and excellent conductivity, are promising for improving the energy density in EDLCs. In this study, an innovative approach was adopted to fabricate CNT-metal electrodes, in which chemical bonds between vertically aligned carbon nanotubes (VACNTs) and Au metal were formed via a linker molecule, resulting in robust, highly electrically conductive CNT-Au bonds without compromising the free-standing nature and quality of the VACNT array. Specifically, VACNT arrays prepared through chemical vapor deposition on an Al₂O₃/Si substrate were transferred onto Au metal while maintaining their free-standing arrangement. The average resistance at the CNT-Au interface was 0.5 kΩ over an area of 1 nm², as measured using an atomic force microscopy-based technique. Supercapacitors fabricated using the prepared VACNT-Au electrodes had a specific capacitance of 50 mF cm^-2 (9.5 F g^-1), thereby outperforming most pure VACNT-based EDLCs. Moreover, these devices exhibited outstanding stability, with 74% capacitance retention after 100,000 charge-discharge cycles.

Voltammetric methods hold promise for the rapid and sensitive quantification of melatonin. This study reports the direct electrochemical quantification of melatonin using carbon nanotube (CNT) fiber cross‐sections as microelectrodes. Six identical highly densified CNT fiber cross‐sections were employed to quantify melatonin in the range of 0.05–100 μM. The limit of detection and quantification were 10 and 35 nM, respectively, with a sensitivity of 0.1322 nA/μM. Interference studies with uric acid, hypoxanthine, and ascorbic acid demonstrate its performance. Real‐world application was highlighted by measuring melatonin in food, pharmaceutical, and human urine samples.

The measurement of glucose through electrochemical methods is a great example to illustrate the practical application of electrochemistry. Although many students enrolled in chemistry classes are familiar with the glucose meter, only a few have delved into the underlying principles governing its operation. This experiment aims to address this gap by introducing students to modern electrochemical measurements, showcasing the potential for analyzing minute sample quantities and reviewing fundamental concepts related to enzymatic catalysis and buffers. The experimental procedure described here involves the utilization of screen-printed gold electrodes for the amperometric detection of glucose in simulated urine. The glucose-containing sample is spiked with glucose oxidase, an enzyme that catalyzes the oxidation of glucose, generating hydrogen peroxide, which is subsequently detected through amperometric measurements. By constructing a calibration graph, students are able to determine the concentration of glucose in simulated urine. While primarily designed for introductory biochemistry laboratory sessions aimed at freshmen students, this experiment can be easily modified and adapted to suit more advanced courses.