3D printable conductive materials for the fabrication of electrochemical sensors:A mini review

The review presents recent developments in the use of conductive materials that can be printed using additive manufacturing (3D printing), enabling the development of mass-produced electrochemical sensors of varying geometries. This review will highlight some key electroanalytical applications of 3D-printed electrochemical sensors and discuss their potential future capabilities. Keywords: 3D printing, Additive manufacturing, Electrochemistry, Conductive electrode, 3D printed electrode, Electrochemical senso

Investigating the effects of primary amine linkers with different carbon chain lengths on the acid dissociation constant (pKa) for covalently immobilized anthraquinone at the electrode surface using linear and non-linear fittings

Electrografting of primary amine linkers is a widely used technique to covalently immobilize redox molecules or biomolecules at the electrode surface as it can produce a uniform and highly stable monolayers. Herein, we discussed the effects of having primary amine linkers with different carbon chain lengths as a medium to attach anthraquinone (AQ) at the electrode surface to study its acid dissociation constant (pKa); anthraquinone was covalently attached to glassy carbon (GC) electrodes in aqueous buffer solutions at different pH values ranging from pH 1 to pH 13. In this study, ethylenediamine (EDA, C2) and hexanediamine (HDA, C6) were used as the primary amine linkers. The pKa values of the surface-bound AQ were determined from the linear and non-linear fittings performed on the graphs of the mid potential (Emid) of the redox peaks for AQ against the pH. The pKa values obtained from the linear fittings were using the value at the intersection point of two linear slopes between two pH gradients, whilst the pKa values for the non-linear fittings were determined according to the Nernst pH reduction theory. Overall, the non-linear fittings can provide us with a reliable and accurate approach in determining the pKa values of AQ

Recycling chocolate aluminium wrapping foil as to create electrochemical metal strip electrodes

The development of low-cost electrode devices from conductive materials has recently attracted considerable attention as a sustainable means to replace the existing commercially available electrodes. In this study, two different electrode surfaces (surfaces 1 and 2, denoted as S1 and S2) were fabricated from chocolate wrapping aluminum foils. Energy dispersive X-Ray (EDX) and field emission scanning electron microscopy (FESEM) were used to investigate the elemental composition and surface morphology of the prepared electrodes. Meanwhile, cyclic voltammetry (CV), chronoamperometry, electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were used to assess the electrical conductivities and the electrochemical activities of the prepared electrodes. It was found that the fabricated electrode strips, particularly the S1 electrode, showed good electrochemical responses and conductivity properties in phosphate buffer (PB) solutions. Interestingly, both of the electrodes can respond to the ruthenium hexamine (Ruhex) redox species. The fundamental results presented from this study indicate that this electrode material can be an inexpensive alternative for the electrode substrate. Overall, our findings indicate that electrodes made from chocolate wrapping materials have promise as electrochemical sensors and can be utilized in various applications

Recent advances on metal nitride materials as emerging electrochemical sensors: A mini review

Metal nitride materials are garnering interest in many fields including electrochemistry, although they are still at an early stage of investigation and underexplored. This mini review provides insights on the latest advancements in the field of electroanalytical chemistry based on metal nitride materials, specifically focusing on the best performing transition metal nitride sensors published between 2017 and 2020 for important targets such as glucose, hydrogen peroxide and dissolved oxygen. Nickel cobalt nitride electrodes demonstrate electrocatalytic behaviours toward glucose oxidation and hydrogen peroxide reduction processes. Meanwhile, zirconium nitride electrodes could replace platinum/carbon electrodes for oxygen reduction reaction. This article also introduces solid molybdenum nitride microdisk electrodes, which can easily be prepared and maintained and show diffusion-control voltammetric responses for the complex peroxodisulfate reduction reaction. This mini review will benefit researchers who would like to delve into the potential of metal nitride electrodes as electrochemical sensor

Two-dimensional SnS and SnSe as hosts of K-ion storage: a first-principles prediction

Potassium ion batteries (KIBs) have attracted remarkable consideration due to their intrinsic safety and huge availability of potassium. However, the large size of the K ion and low charge−discharge efficiency are the main obstacles to the progress of KIBs. To overcome these hurdles, we chose SnS and SnSe monolayers as K anodes for KIBs due to their layered structural assemblies, wider surface area to accommodate more K content, and high thermal stabilities. First-principles simulations were carried out to study the electronic properties and K storage capability of SnS and SnSe monolayers as anode materials for KIBs. We found that K adsorption enhances the electrical conductivity of both SnS and SnSe monolayers, which become metallic after the adsorption of a very minor concentration of K. The outcomes of the ab initio molecular dynamic simulations display the thermal stability of the host materials for KIBs. According to our calculations, the theoretical capacities of SnS and SnSe monolayers are 355 and 271 mA h/g, respectively. Consequently, we obtain very low average voltages of 0.45 V for SnS and 0.36 V for SnSe monolayers. In addition, the low diffusion barriers for the K-ion on SnS and SnSe monolayers are 0.14 and 0.16 eV, correspondingly, illustrating the fast ion transfer rate with rapid potassiation and depotassiation. These intriguing results suggest that SnS and SnSe monolayers could be promising anode materials for KIBs

Qualitative and quantitative methods of Capsaicinoids: a mini‑review

The interest in capsaicinoids increased recently due to its potential for commercial use, including food products, dietary supplements, pharmaceutical, and self-defence products. Hence, there is an urge to develop an efficient qualitative and quantitative method of capsaicinoids so as to protect the consumer right and upright the regulation regarding their concentration in the aforementioned products. Therefore, this mini-review is aimed at assisting readers in choosing the best analytical method for detecting capsaicinoids in a variety of samples, which includes selected recent journals. HPLC, NMR spectroscopy, and electrochemical sensors are among the analytical methods chosen in this review. The advantages, disadvantages, and limitations of each analytical method are thoroughly examined. It also discusses the validation methods such as the accuracy, precision, sensitivity, selectivity, and detection limits of the techniques. This mini-review is believed to benefit not only researchers, but also the related regulatory institutions in the determination of capsaicinoids

Hexanediamine monolayer electrografted at glassy carbon electrodes enhances oxygen reduction reaction in aqueous neutral media

This study presents for the first time the electrocatalytic behaviour of hexanediamine (HDA) monolayer electrografted at glassy carbon (GC) electrodes that enhanced oxygen reduction reaction (ORR) in aqueous neutral media. HDA modified GC electrodes gave a higher current density than platinum bare electrodes based on the cyclic voltammograms (CV), although a ~0.21 V vs. Ag/AgCl higher onset potential was observed at −0.1 mA cm-2. Electrochemical impedance spectra (EIS) showed that the electrocatalytic reaction on HDA monolayer film towards dissolved oxygen molecules is controlled by diffusion and charge transfer processes. From the scan rate studies and the Laviron equation, it was found that the ORR on this modified electrode proceeded via a fast four-electrons transfer

Identification of chrysotile in brake pads and linings from Malaysian vehicles and heavy vehicles by using Polarized Light Microscope (PLM)

Exposure to types of asbestos such as chrysotile and crocidolite increases respiratory disease risks such as lung cancer, mesothelioma, and asbestosis. Nevertheless, asbestos products banning in Malaysia is only limited to crocidolite as per stated in OSHA (Prohibition of Use of Substance) Order 1999, though other types are highly suspected to be found in asbestos-containing materials (ACM) like brake pads and linings. This study ascertains the presence of asbestos fibres, particularly chrysotile, in brake pads and linings used in Malaysia's vehicle and heavy vehicle sector. Seven different brake pads; three from vehicle brands, and four from heavy vehicle brands were collected by bulk sampling approaches from the market and field. Dust fibres were extracted using slow grinding method and analysed under Polarized Light Microscope (PLM). The fibre characteristics such as colour, morphology, pleochroism, extinction, and dispersion staining technique were examined, referring the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods (NMAM) 9002. Additionally, the observed samples also were verified by an accredited lab to support the authenticity of the outcome. From the analysis and lab results, chrysotile fibres were consistently detected in all brake pad samples, fulfilling the fibre characteristics and positive elongation signs

Deep eutectic solvent coated cerium oxide nanoparticles based polysulfone membrane to mitigate environmental toxicology

In this study, ceria nanoparticles (NPs) and deep eutectic solvent (DES) were synthesized, and the ceria-NP’s surfaces were modified by DES to form DES-ceria NP filler to develop mixed matrix membranes (MMMs). For the sake of interface engineering, MMMs of 2%, 4%, 6% and 8% filler loadings were fabricated using solution casting technique. The characterizations of SEM, FTIR and TGA of synthesized membranes were performed. SEM represented the surface and cross-sectional morphology of membranes, which indicated that the filler is uniformly dispersed in the polysulfone. FTIR was used to analyze the interaction between the filler and support, which showed there was no reaction between the polymer and DES-ceria NPs as all the peaks were consistent, and TGA provided the variation in the membrane materials with respect to temperature, which categorized all of the membranes as very stable and showed that the trend of stability increases with respect to DES-ceria NPs filler loading. For the evaluation of efficiency of the MMMs, the gas permeation was tested. The permeability of CO2 was improved in comparison with the pristine Polysulfone (PSF) membrane and enhanced selectivities of 35.43 (αCO2/CH4) and 39.3 (αCO2/N2) were found. Hence, the DES-ceria NP-based MMMs proved useful in mitigating CO2 from a gaseous mixture