Synthesis of a novel In2O3 hollow cube using in-situ partial oxidation with enhanced gas sensing platform to detect C3H8

Abstract

Indium oxide hollow cubes were made using a simple hydrothermal technique and calcination process, its crystalline form was cubic bixbyite-type, and had high purity of the calcined sample. Urea was selected as alkaline source, which was capable of cooperating with In3+ to create indium-urea complexes, hindering the growth of certain surfaces, further controlled the shape of the product. Comparing with In2O3 prepared with different amounts of urea, it was found that the best performing In2O3 hollow cube (In2O3-5) synthesized at a molar ratio (InCl3:CH4N2O) of 1:5, its form was a hollow cubic structure made of regular spherical particles stacked, possessed a relatively large specific surface area (64.9 m2/g) which was 1.2 times greater than In2O3-1, and it had smallest grain size (15 nm) compare with In2O3-1 (28 nm), In2O3-3 (23 nm), In2O3-8 (16 nm), and In2O3-10 (20 nm). The In2O3-5 sensor's sensitivity peaked at 180 °C, which is its ideal operating temperature (response value could reach 84.1), the response recovery time was 9s, also exhibited excellent selectivity for C3H8 (CO: 21.7, C2H4: 24.8, C2H5OH: 28.6, H2: 17.9 and H2S: 12.2). The results showed that In2O3-5 with a hollow cube structure formed more necessary channels for vacant oxygen species transport and further contributed to the sensitivity of the material to gases.