Nano-size effects in graphite/graphene structure exposed to cesium vapor

Abstract

A thermionic energy converter with a nickel collector and cesium vapor as a working gas was studied, and an abnormally low value of the surface work function of ≈1 eV was obtained if the collector was covered by a thin carbon layer. Scanning electron microscopy x-ray microanalysis data of the elemental composition of the collector's surface after its long exposure to plasma indicate that the carbon structure was intercalated with cesium atoms, and this change to surface structure can be a reason for the anomalously low work function ∼1 eV. The thermionic energy converter with such a collector demonstrated high heat-to-electric power conversion efficiency up to ∼20%.

Low-Temperature Thermionic Converters Based on Metal–Nanostructured Carbon Composites

“…It has long been known that the presence of caesium on the surface of refractory metal anodes affects their work function. An experiment closer to ours was described in [45]. For a nickel anode with a nanocarbon coating (at its operating temperature of 900 K), it was found that adsorption of Cs can reduce the work function from 4.5 to 1.5 eV, and intercalation with caesium of the upper carbon layer (due to defects in it) with the formation of complexes Cs-O-Cs rising above the surface can reduce the work function to 0.95 eV at a sufficient their density on the anode surface.…”

“…Residual gases in the vacuum chamber in which the emission of electrons occurs, i.e. their ionization and interaction with the cathode and anode, also have a significant effect [15,27,35,[43][44][45]. Thus, the ad-sorption of some types of atoms can significantly change the electronic structure of the surface, including the formation of emission centres with a reduced work function.…”

Calculation of Graphene Work Function Variations Due to Alkali Metal + Oxygen Adsorption

“…[6] Mustafaev et al studied the graphite/graphene structure exposed to cesium vapor with trace amount of oxygen, and an abnormally low value of the surface work function of 1 eV was obtained. [7] Ma et al studied the way of adding oxygen in cesium-filled thermionic power generation device and its influence on thermoelectric performance; they found that the work function of the electrode after absorbing oxygen was lower, thus effectively improving the thermoelectric performance of the device. [8] The adsorption of AMs on the surface can lead to the decrease of work function, which was theoretically explained by Langmuir for the first time.…”

Magnetic and Plasmonic Composite Nanostructures for Creating Optical Filters at Substance and Material Diagnostics Systems

“…Введение. Стремительное развитие возникшего в конце XX в. направления научно-технических исследований, получившего название "нанотехнологии", позволяет предлагать новые решения ряда комплексных задач контроля и диагностики окружающей среды [1][2][3], веществ [4,5] и материалов [6][7][8], создания приборов нового поко-ления [9][10][11] и разработки энергетических систем [12,13]. Особую актуальность представляют оптические свойства нанообъектов и возможность их использования при реализации инфокоммуникационных систем передачи сигналов с мультиплексированием, демультиплексированием и фильтрацией в соответствующем частотном диапазоне.…”