Design of Amphibious Vehicle for Unmanned Mission in Water Quality Monitoring Using Internet of Things.

Unmanned aerial vehicles (UAVs) have gained significant attention in recent times due to their suitability for a wide variety of civil, military, and societal missions. Development of an unmanned amphibious vehicle integrating the features of a multi-rotor UAV and a hovercraft is the focus of the present study. Components and subsystems of the amphibious vehicle are developed with due consideration for aerodynamic, structural, and environmental aspects. Finite element analysis (FEA) on static thrust conditions and skirt pressure are performed to evaluate the strength of the structure. For diverse wind conditions and angles of attack (AOA), computational fluid dynamic (CFD) analysis is carried out to assess the effect of drag and suitable design modification is suggested. A prototype is built with a 7 kg payload capacity and successfully tested for stable operations in flight and water-borne modes. Internet of things (IoT) based water quality measurement is performed in a typical lake and water quality is measured using pH, dissolved oxygen (DO), turbidity, and electrical conductivity (EC) sensors. The developed vehicle is expected to meet functional requirements of disaster missions catering to the water quality monitoring of large water bodies.

RuO2-ReO3 composite nanofibers for efficient electrocatalytic responses.

We present a facile synthetic route to ruthenium dioxide (RuO2)-rhenium oxide (ReO3) electrospun composite nanofibers and their electrocatalytic responses for capacitance and H2O2 sensing. The contents of rhenium oxide of electrospun ruthenium dioxide (RuO2) were carefully controlled by an electrospinning process with the preparation of the precursor solutions followed by the thermal annealing process in air. The electrochemical applications of RuO2-ReO3 electrospun composite nanofibers were then investigated by modifying these materials on the surface of glassy carbon (GC) electrodes, RuO2-ReO3(n)/GC (n = 0.0, 0.07, 0.11, and 0.13), where n denotes the relative atomic ratio of Re to the sum of Ru and Re. Specific capacitance and H2O2 reduction sensitivity were remarkably enhanced depending on the amount of ReO3 increased. Among the four compositions of RuO2-ReO3(n), RuO2-ReO3(0.11)/GC showed the highest performances, i.e., a 20.9-fold higher specific capacitance (205 F g(-1) at a potential scan rate (v) of 10 mV s(-1); a capacity loss of 19% from v = 10 to 2000 mV s(-1)) and a 7.6-fold higher H2O2 reduction sensitivity (668 µA mM(-1) cm(-2), normalized by GC disk area), respectively, compared to only RuO2/GC.

Cerium-Based Perovskite Mixed Metal Oxide as the Radical Scavenger for PEM Fuel Cells Operating under Low Humidity Conditions.

When the polymer electrolyte membrane fuel cell (PEMFC) is operated under low humidity, the proton conductivity decreases due to membrane dehydration, causing adverse effects on fuel cell performance. Introducing appropriate additives to the membrane and catalyst layer to prevent membrane degradation at low humidity brings significant performance improvements to proton exchange membrane fuel cells. We developed a perovskite-structured multi-metal oxide Ce0.667Zr0.05Ti0.95O3-δ (CZTO) with high radical scavenging properties and good structural stability. The nanostructured ceramic CZTO is introduced into the membrane and cathode catalyst layer to improve the durability of the membrane electrode assembly. The Nafion-CZTO membrane exhibited maximum power densities of 1298 and 519 mW cm-2 at 100 and 20% relative humidity, respectively. The improved performance of Nafion-CZTO membranes over commercial Nafion membranes is due to the high proton conductivity and better radical scavenging properties of the CZTO additive. In addition, the expected positive effects of applying CZTO additives to the catalyst layer are verified by low charge transfer resistance and high electrochemical surface activity of the CZTO catalyst through electrochemical impedance spectroscopy and electrochemical surface area analyses.

Analysis of Ionic Domains on a Proton Exchange Membrane Using a Numerical Approximation Model Based on Electrostatic Force Microscopy.

Understanding the ionic channel network of proton exchange membranes that dictate fuel cell performance is crucial when developing proton exchange membrane fuel cells. However, it is difficult to characterize this network because of the complicated nanostructure and structure changes that depend on water uptake. Electrostatic force microscopy (EFM) can map surface charge distribution with nano-spatial resolution by measuring the electrostatic force between a vibrating conductive tip and a charged surface under an applied voltage. Herein, the ionic channel network of a proton exchange membrane is analyzed using EFM. A mathematical approximation model of the ionic channel network is derived from the principle of EFM. This model focusses on free charge movement on the membrane based on the force gradient variation between the tip and the membrane surface. To verify the numerical approximation model, the phase lag of dry and wet Nafion is measured with stepwise changes to the bias voltage. Based on the model, the variations in the ionic channel network of Nafion with different amounts of water uptake are analyzed numerically. The mean surface charge density of both membranes, which is related to the ionic channel network, is calculated using the model. The difference between the mean surface charge of the dry and wet membranes is consistent with the variation in their proton conductivity.

Highly branched RuO2 nanoneedles on electrospun TiO2 nanofibers as an efficient electrocatalytic platform.

Highly single-crystalline ruthenium dioxide (RuO2) nanoneedles were successfully grown on polycrystalline electrospun titanium dioxide (TiO2) nanofibers for the first time by a combination of thermal annealing and electrospinning from RuO2 and TiO2 precursors. Single-crystalline RuO2 nanoneedles with relatively small dimensions and a high density on electrospun TiO2 nanofibers are the key feature. The general electrochemical activities of RuO2 nanoneedles-TiO2 nanofibers and Ru(OH)3-TiO2 nanofibers toward the reduction of [Fe(CN)6](3-) were carefully examined by cyclic voltammetry carried out at various scan rates; the results indicated favorable charge-transfer kinetics of [Fe(CN)6](3-) reduction via a diffusion-controlled process. Additionally, a test of the analytical performance of the RuO2 nanoneedles-TiO2 nanofibers for the detection of a biologically important molecule, hydrogen peroxide (H2O2), indicated a high sensitivity (390.1 ± 14.9 µA mM(-1) cm(-2) for H2O2 oxidation and 53.8 ± 1.07 µA mM(-1) cm(-2) for the reduction), a low detection limit (1 µM), and a wide linear range (1-1000 µM), indicating H2O2 detection performance better than or comparable to that of other sensing systems.