Morpho-Butterfly Inspired Lamella-based Optical Sensors for Measuring Percent Level Concentrations of H2 and CO with Au and CeO2

Abstract

Morpho-Butterfly inspired lamella structures were fabricated to make a multivariable optical sensor for measuring percent level concentrations of H2 and CO in a high temperature, zero-O2 environment. The SiO2 and Si3N4 3D structures were covered with gold nanoparticles (AuNPs) and cerium IV dioxide (CeO2) and exposed to varying concentrations of H2 and CO at 300°C. Experiments with AuNP sizes with an average diameter of 11 ± 3 nm and 3 ± 0.5 nm (larger and small AuNPs, respectively) showed that the larger AuNPs had a stronger response to the same concentrations of H2 and CO with less CO saturation and baseline drift. Further testing in the presence of 1% hydrocarbons (HCs) as an interfering gas showed excellent response to up to 17% H2 and CO in a zero-O2 environment with changes in reflected intensity of -13.1 ± 0.4% for H2 and -5.8 ± 0.3% for CO. The presence of HCs did not induce any baseline drift, with the total amount of drift being less than 0.5% over 13 hours of testing at 300°C.