High-Performance BaTiO3 Film Based on Aqueous Tape Casting for Ultrathin MLCC Applications

Environment-friendly aqueous tape-casting are proposed as an inevitable tendency for producing a high-quality BaTiO3-based film in the development of ultra-thin multilayer ceramic capacitors. In this study, aqueous BaTiO3 suspension with high solids loading produced by using polycarboxylate ammonium salt APC (dispersant), proprietary acrylic formulation binder solution WB4101 (binder), and acrylic resin PL002 (plasticizer), respectively. It is demonstrated that the green density, tensile strength, and strain at failure of the 9.5-μm-thin BaTiO3 tape achieves 3.65 g/cm3, 7.65 MPa, and 11%, respectively. In particular, the capacitance and dielectric loss of BaTiO3-based MLCC chips at room temperature are found to be approximately 28 nF and 0.02 compatible with Pt electrodes. Additionally, the TCC, ferroelectric hysteresis loops, change of dielectric constants versus DC-BIAS field, and evolution of electrical resistivity under accelerated DC stressing of BaTiO3-based MLCC are studied. The results provide an effective method for the future improvement in aqueous MLCC applications.

Activation of Porous Pt Electrodes Deposited on YSZ Electrolyte by Nitric Acid Treatment

The effect of nitric acid treatment on the electrochemical performance of porous Pt electrodes deposited on YSZ (abbreviation from yttria stabilized zirconia) electrolyte was investigated. Two identical symmetrical Pt/YSZ/Pt cells with porous Pt electrodes were fabricated, after which the electrodes of the first cell were kept as sintered, while those of the second cell were impregnated with HNO3 solution. The electrochemical behavior of the prepared electrodes was studied using impedance spectroscopy and cyclic voltammetry. Significant reduction of the polarization resistance of the HNO3-treated electrodes was revealed. The observed enhancement of the electrochemical performance of porous Pt electrodes was assumed to be caused by adsorption of NOx-species on YSZ and Pt surfaces, which promotes oxygen molecules dissociation and transport to the triple phase boundary by the “relay-race” mechanism. The obtained results allow for considering the nitric acid treatment of a porous Pt electrode as an effective way of electrode activation.

Rapid, multianalyte detection of opioid metabolites in wastewater

By monitoring opioid metabolites, wastewater-based epidemiology (WBE) could be an excellent tool for real-time information on consumption of illicit drugs. A key limitation of WBE is the reliance on costly laboratory-based techniques that require substantial infrastructure and trained personnel, resulting in long turnaround times. Here, we present an aptamer-based graphene field effect transistor (AptG-FET) platform for simultaneous detection of three different opioid metabolites. This platform provides a reliable, rapid, and inexpensive method for quantitative analysis of opioid metabolites in wastewater (WW). The platform delivers a limit of detection (LOD) 2-3 orders of magnitude lower than previous reports, but in line with the concentrations range (pg/ml to ng/ml) of these opioid metabolites present in real samples. To enable multianalyte detection we developed a facile, reproducible, and high yield fabrication process producing twenty G-FETs with integrated side gate platinum (Pt) electrodes on a single chip. Our devices achieved the simultaneous and selective multianalyte detection of three different metabolites: Noroxycodone (NX), 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), and Norfentanyl (NF) in wastewater.

The UV Effect on the Chemiresistive Response of ZnO Nanostructures to Isopropanol and Benzene at PPM Concentrations in Mixture with Dry and Wet Air

Towards the development of low-power miniature gas detectors, there is a high interest in the research of light-activated metal oxide gas sensors capable to operate at room temperature (RT). Herein, we study ZnO nanostructures grown by the electrochemical deposition method over Si/SiO2 substrates equipped by multiple Pt electrodes to serve as on-chip gas monitors and thoroughly estimate its chemiresistive performance upon exposing to two model VOCs, isopropanol and benzene, in a wide operating temperature range, from RT to 350 °C, and LED-powered UV illumination, 380 nm wavelength; the dry air and humid-enriched, 50 rel. %, air are employed as a background. We show that the UV activation allows one to get a distinctive chemiresistive signal of the ZnO sensor to isopropanol at RT regardless of the interfering presence of H2O vapors. On the contrary, the benzene vapors do not react with UV-illuminated ZnO at RT under dry air while the humidity’s appearance gives an opportunity to detect this gas. Still, both VOCs are well detected by the ZnO sensor under heating at a 200–350 °C range independently on additional UV exciting. We employ quantum chemical calculations to explain the differences between these two VOCs’ interactions with ZnO surface by a remarkable distinction of the binding energies characterizing single molecules, which is −0.44 eV in the case of isopropanol and −3.67 eV in the case of benzene. The full covering of a ZnO supercell by H2O molecules taken for the effect’s estimation shifts the binding energies to −0.50 eV and −0.72 eV, respectively. This theory insight supports the experimental observation that benzene could not react with ZnO surface at RT under employed LED UV without humidity’s presence, indifference to isopropanol.