Cavity ring-down spectroscopy (CRDS) is an ultra-sensitive direct absorption technique that offers unique advantages compared to other spectroscopic techniques. It can measure cooperative enhanced absorption for weakly absorbing species at ultra-low concentrations. This is achieved by leveraging the concept of a stable optical cavity, which allows for an effective optical path length of several kilometers within a small physical sample length. One advantage of CRDS technology is that it is unaffected by fluctuations in the intensity of the light source. Another advantage is its applicability to the detection of atoms, molecules, and radicals in the atmosphere. Additionally, the equipment associated with this technology is compact and robust. This paper will first introduce the fundamental principles and setup of CRDS technology. It will then provide an overview of the characteristics of the fabrication equipment and the high reflectivity mirror coating process used in cavity ring-down spectroscopy.

In this study, we successfully demonstrated a fuel cell fabrication method using a platinum-samarium-doped ceria (Pt-SDC) composite cathode, which could reduce the platinum content while maintaining the same thickness as the functional layer. The Pt-SDC composite cathode was deposited by a sputtering process in which two materials were simultaneously deposited by a co-sputtering system. Despite the decreased platinum content in the composite cathode, we achieved high performance of the fuel cell since Pt-SCD was able to form triple-phase boundaries (TPBs) not only at the interface between the cathode and the electrolyte but at the entire volumetric surface of the cathode. This composite cathode revealed that Pt-SDC could enhance the oxygen reduction reaction rate by enlarging the TPB site in the cathode. The fuel cell fabricated in this study with a composite cathode demonstrated improved performance at 1.66 times the peak power density of a pristine fuel cell.

Energy devices in modern society require high efficiency, carbon neutrality, and the capability of distributed power generation. A fuel cell is an energy conversion device, that satisfies all of these requirements. However, most fuel cells use hydrogen as a fuel, and more than half of hydrogen is currently produced through hydrocarbon reforming, resulting in significant energy loss. Additionally, the storage and supply of hydrogen require costly systems, and a large amount of energy is consumed during compression or liquidation processes. This paper develops a solid oxide fuel cell, that uses hydrocarbon directly as fuel to resolve this problem. A small amount of Ru is mixed with the Ni-based electrode, for the effective internal reforming of hydrocarbons. For rapid deposition of YSZ electrolytes, we developed a reactive sputtering process, using a DC power source. The developed thin-film solid oxide fuel cell, showed a performance of 76 mW/cm² at 500℃ using methane as fuel.

In this study, Yttria-stabilized zirconia (YSZ) functional layers were applied with different thin-film fabrication process such as sputtering and atomic layer deposition (ALD) to enhance oxygen reduction reaction (ORR) for solid oxide fuel cells. We confirmed that the YSZ functional layer deposited with sputtering showed relatively low grain boundary density, while the YSZ functional layer deposited with the ALD technique clearly indicated high grain boundary density through scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results. The YSZ functional layer coated with the ALD technique revealed that more ORR kinetics can occur using high grain boundary density than the functional layer deposited with sputtering. The peak power density of the SOFC deposited with ALD YSZ indicates 2-folds enhancement than the pristine SOFC.

Solid oxide fuel cell is a next generation energy conversion device that can efficiently convert the chemical energy of fuel into electrical energy. Fuel flexibility is one of the advantages of SOFCs over other types of fuel cells. SOFCs can operate with hydrocarbon type fuel. While nickel based composite is commonly used in direct methane fueled SOFC anode because of its great catalytic activity for methane reforming, the direct use of hydrocarbon fuels with pure Ni anode is usually insufficient for facile anode kinetics, and also deactivates the anode activity because of carbon deposition upon prolonged operation. In this report, the Ni based anodes with 20 nm thick catalytic functional layers, i.e., Pt, Ru, and Pt-Ru alloy, are fabricated by using the co-sputtering method to enhance the anode activity and power density of direct-methane SOFC operating at 500℃.

In this study, polymer bipolar plates for ultra-light polymer electrolyte membrane fuel cells (PEMFCs) were fabricated. Various methods for current collecting were applied to ensure electron conductivity of the polymer bipolar plates. Direct wire contact and Ag sputter process were applied. The Ag current collecting layer fabricated by the sputter process showed a well-covered and defectless surface. After preparations of bipolar plates, the effects of current collecting methods of bipolar plates on the electrochemical properties of PEMFCs were systematically investigated. The maximum power density of PEMFCs with the Ag current collecting of layered polymer bipolar plates decreased 37.39% because of increased ohmic resistance. However, the power/weight of PEMFCs with the Ag current collecting of layered polymer bipolar plates increased 27.23% because of the dramatically reduced weight (-50.63%) of bipolar plates compared to the graphite bipolar plates. We affirm that results in this report can provide meaningful insight for portable electrochemical energy devices.