Synthesis and electrochemical characterization of Si/TiO2/Au composite anode: Efficient oxygen evolution and hydroxyl radicals generation

Preparation of Ti/RuO2-IrO2 electrodes and their application in broad-spectrum electrochemical detection of COD

An electrode with RuO2 and IrO2 co-deposited on a Ti surface (Ti/RuO2-IrO2), notable for its high catalytic activity and stability, was developed for the rapid and environmentally friendly electrochemical determination of chemical oxygen demand (COD). This study thoroughly examined factors influencing electrode preparation, COD detection mechanisms, and the factors affecting COD detection, as well as broad-spectrum analysis. Under optimal conditions, which include a deposition time of 53.5 min, a current density of 5.5 mA/cm2, and 2.35 mmol of RuCl3, the electrode achieved a linear correlation coefficient of 0.99 for COD detection. The co-doping of RuO2 and IrO2 significantly enhanced the electrode's specific surface area and charge transfer rate, thereby improving the oxidation of organic compounds. The detection limit for COD was established at 1.8 mg/L, with a range of 0-250 mg/L, using an oxidation potential of 0.90 V and an electrolysis time of 150 s at an initial electrolyte pH of 6 with 0.03 mol/L NaNO3. The electrode effectively oxidized organic compounds across this range and demonstrated tolerance to chloride concentrations up to 800 mg/L. Electrode stability was confirmed through 30 repetitive cycles with no significant performance degradation. The detection results for simulated water samples were in strong agreement with the results obtained from the dichromate colorimetric method, with a linear equation of y = 0.01x+1.11, with an R2 of 0.99. The detection outcomes for six different sources of real water samples indicated consistent correlation between the electrochemical COD detection method using the Ti/RuO2-IrO2 electrode and the dichromate colorimetric method. This research showed the Ti/RuO2-IrO2 electrode has certain potential as COD detection element, leveraging its high charge transfer rate and extensive active area.

Step-by-step guide for electrochemical generation of highly oxidizing reactive species on BDD for beginners

Selecting the ideal anodic potential conditions and corresponding limiting current density to generate reactive oxygen species, especially the hydroxyl radical (•OH), becomes a major challenge when venturing into advanced electrochemical oxidation processes. In this work, a step-by-step guide for the electrochemical generation of •OH on boron-doped diamond (BDD) for beginners is shown, in which the following steps are discussed: i) BDD activation (assuming it is new), ii) the electrochemical response of BDD (in electrolyte and ferri/ferro-cyanide), iii) Tafel plots using sampled current voltammetry to evaluate the overpotential region where •OH is mainly generated, iv) a study of radical entrapment in the overpotential region where •OH generation is predominant according to the Tafel plots, and v) finally, the previously found ideal conditions are applied in the electrochemical degradation of amoxicillin, and the instantaneous current efficiency and relative cost of the process are reported.

New Insights on Designing the Next-Generation Materials for Electrochemical Synthesis of Reactive Oxidative Species Towards Efficient and Scalable Water Treatment: A Review and Perspectives

Electrochemical water remediation technologies offer several advantages and flexibility for water treatment and degradation of contaminants. These technologies generate reactive oxidative species (ROS) that degrade pollutants. For the implementation of these technologies at an industrial scale, efficient, scalable, and cost-effective in-situ ROS synthesis is necessary to degrade complex pollutant mixtures, treat large amount of contaminated water, and clean water in a reasonable amount of time and cost. These targets are directly dependent on the materials used to generate the ROS, such as electrodes and catalysts. Here, we review the key design aspects of electrocatalytic materials for efficient in-situ ROS generation. We present a mechanistic understanding of ROS generation, including their reaction pathways, and integrate this with the key design considerations of the materials and the overall electrochemical reactor/cell. This involves tunning the interfacial interactions between the electrolyte and electrode which can enhance the ROS generation rate up to ~ 40% as discussed in this review. We also summarized the current and emerging materials for water remediation cells and created a structured dataset of about 500 electrodes and 130 catalysts used for ROS generation and water treatment. A perspective on accelerating the discovery and designing of the next generation electrocatalytic materials is discussed through the application of integrated experimental and computational workflows. Overall, this article provides a comprehensive review and perspectives on designing and discovering materials for ROS synthesis, which are critical not only for successful implementation of electrochemical water remediation technologies but also for other electrochemical applications.

A High-Performance Self-Supporting Electrochemical Biosensor to Detect Aflatoxin B1

High-performance electrochemical biosensors for the rapid detection of aflatoxin B1 (AFB₁) are urgently required in the food industry. Herein, a multi-scaled electrochemical biosensor was fabricated by assembling carboxylated polystyrene nanospheres, an aptamer and horseradish peroxidase into a free-standing carbon nanofiber/carbon felt support. The resulting electrochemical biosensor possessed an exceptional performance, owing to the unique structures as well as the synergistic effects of the components. The 3D porous carbon nanofiber/carbon felt support served as an ideal substrate, owing to the excellent conductivity and facile diffusion of the reactants. The integration of carboxylated polystyrene nanospheres with horseradish peroxidase was employed as a signal amplification probe to enhance the electrochemical responses via catalyzing the decomposition of hydrogen peroxide. With the aid of the aptamer, the prepared sensors could quantitatively detect AFB₁ in wine and soy sauce samples via differential pulse voltammetry. The recovery rates of AFB₁ in the samples were between 87.53% and 106.71%. The limit of detection of the biosensors was 0.016 pg mL^-1. The electrochemical biosensors also had excellent sensitivity, reproducibility, specificity and stability. The synthetic strategy reported in this work could pave a new route to fabricate high-performance electrochemical biosensors for the detection of mycotoxins.

A Chemosensor Based on Gold Nanoparticles and Dithiothreitol (DTT) for Acrylamide Electroanalysis

Rapid and simple electroanalysis of acrylamide (ACR) was feasible by a gold electrode modified with gold nanoparticles (AuNPs) and dithiothreitol (DTT) with enhanced detection sensitivity and selectivity. The roughness of bare gold (Au) increased from 0.03 μm to 0.04 μm when it was decorated with AuNPs. The self-assembly between DTT and AuNPs resulted in a surface roughness of 0.09 μm. The DTT oxidation occurred at +0.92 V. The Au/AuNPs/DTT surface exhibited a surface roughness of 0.24 μm after its exposure to ACR with repeated analysis. SEM imaging illustrated the formation of a polymer layer on the Au/AuNPs/DTT surface. Surface plasmon resonance analysis confirmed the presence of AuNPs and DTT on the gold electrode and the binding of ACR to the electrode's active surface area. The peak area obtained by differential pulse voltammetry was inversely proportional to the ACR concentrations. The limit of detection (LOD) and the limit of quantitation (LOQ) were estimated to be 3.11 × 10-9 M and 1 × 10-8 M, respectively, with wide linearity ranging from 1 × 10-8 M to 1 × 10-3 M. The estimated levels of ACR in potato chips and coffee samples by the sensor were in agreement with those of high-performance liquid chromatography.