A Study on Electric Conductivity of Phosphoric Acid Supported on Nano-Pore Rice Husk Silica in H<SUB>2</SUB>|Pt|H<SUB>3</SUB>PO<SUB>4</SUB>/RHS|Pt|O<SUB>2</SUB> Fuel Cells

Abstract

A direct current (DC) operating voltage and luminescence property of red electroluminescent (EL) devices with and/or without a silicon dioxide (SiO2) layer at interface between nanocrystalline Si (nc-Si) region and Si substrate has investigated. The removal of SiO2 layer in the EL device led to the lowering of DC operating voltage from 4.0 up to 2.0 V and the increase of luminescence intensity more than one order of magnitude. The external quantum efficiency of red luminescence from the EL device without the SiO2 layer at the DC operating voltage of 3.0 V was 0.5%. These were realized by the efficient and easy injection of carriers to the radiative recombination centers in the nc-Si region due to the removal of SiO2 layer. These results indicate that the removal of SiO2 layer is drastically improved the DC operating voltage and luminescence intensity for the nc-Si based EL device.

Interpretation on Nanoporous Network Structure in Rice Husk Silica Layer: A Graph Model

“…The rice grain consists of the brown rice and the hull or husk which encloses the brown rice. The husk weighs about 20% of the total grain and its thickness varies from 50 to 100 μm. , The husk is divided into three layersan outer 50 nm cellulose layer, a 2–5 μm silica layer, and an inner thick cellulose layer. − The elemental analysis of the husk indicates 5–10 wt % Si, 0.50 wt % K, 0.07 wt % Na, and 0.6 wt % Al on the basis of organics. , Thermal treatment of the rice husk in a controlled atmosphere produces silica particles with high purity, high surface area, nanometer pores, and high chemical reactivity. − Recently, the rice husk silica has been studied as a sustainable and environmentally friendly silica source − as well as a multifunctional mesoporous material. − Besides the possible applications of the thermally produced rice husk silica, there is also a question on the origin of its pore, i.e., whether it exists in the fresh rice husk or grows during the thermal process. To investigate the whole picture, we have conducted studies on the properties and structure of the silica layer in the fresh rice husk. , As a result, we report a porous nanoscaled network in the layer and its interpretation from the view of a mathematical graph in this study.…”