Preparation of Tin Oxide Quantum Dots in Aqueous Solution and Applications in Semiconductor Gas Sensors

Abstract

Tin oxide quantum dots (QDs) were prepared in aqueous solution from the precursor of tin dichloride via a simple process of hydrolysis and oxidation. The average grain size of QDs was 1.9 nm. The hydrothermal treatment was used to control the average grain size, which increased to 2.7 and 4.0 nm when the operating temperatures of 125 and 225 °C were employed, respectively. The X-ray photoelectron spectroscopy (XPS) spectrum and X-ray diffraction analysis (XRD) pattern confirmed a rutile SnO2 system for the QDs. A band gap of 3.66 eV was evaluated from the UV-VIS absorption spectrum. A fluorescence emission peak was observed at a wavelength of 300 nm, and the response was quenched by the high concentration of QDs in the aqueous solution. The current-voltage (I-V) correlation inferred that grain boundaries had the electrical characteristics of the Schottky barrier. The response of the QD thin film to H2 gas revealed its potential application in semiconductor gas sensors.

Semiconductor Photocatalyst of Tin Oxide Quantum Dots Prepared in Aqueous Solution for Degradation of Organic Pollutants in Contaminated Water

“…SnO 2 QDs were prepared from the analytical source reagents of SnCl 2 •2H 2 O and CH 4 N 2 S by a facile method, which had been described before [21,22]. SnCl 2 •2H 2 O and CH 4 N 2 S were mixed with mole ratio of 10:1 by dissolving into deionized water.…”

Fluorescence Characteristics of Aqueous Synthesized Tin Oxide Quantum Dots for the Detection of Heavy Metal Ions in Contaminated Water

“…SnO 2 QDs were synthesized in the aqueous solution by a facial method [36]. Analytical reagents of SnCl 2 ·2H 2 O (≥98.0%, Sinopharm Chemical Reagent Co., Ltd., Shanghai, China) and thiourea (CH 4 N 2 S, ≥99.0%, Sinopharm Chemical Reagent Co., Ltd., Shanghai, China) were used as raw materials.…”

Room-Temperature Semiconductor Gas Sensors: Challenges and Opportunities

“…Accordingly, the solution-processable nano-crystalline metal oxides, 41,42,60,61 not necessarily CQDs, have also attracted much attention. The RT gas-sensing effect have been observed on NO 2 -sensitive SnO 2 quantum wires (QWs), 62 H 2 -sensitive SnO 2 QDs, 63 H 2 S-sensitive ZnO, 64 and NH 3 -sensitive TiO 2 QDs. 65 One key challenge facing the commercialization of CQD RT gas sensors is to achieve simultaneously ultrahigh sensitivity and high signal-to-noise ratio (SNR).…”