Broad-spectrum UV absorption and gas-sensing improvement of ZnSnO3 cubic particles based on Al-doping and nano-TiO2 decoration

Abstract

Al-doped ZnSn(OH)6 crystalline precursors (Zn1-xAlxSn(OH)6+x) were synthesized with 4 wt% triethanolamine (TEOA). After dehydration of the precursors at high temperature (HT), the resulting Zn1-xAlxSnO3+x/2 (denoted as ZAxSO) samples with amorphous structure were obtained. The phase structure transition can be significantly distinguished by their XRD patterns. The pristine ZnSnO3 sample composed of microscale particles shows an excellent ultraviolet absorption from 200 to 400 nm, and Al-doping makes its UV absorption weakened in the wavelength of 300–400 nm. However, nano-TiO2 decoration enables the UV absorption strengthened in the wavelength range. Less content of Al-doping (x≤0.15) can improve the ethanol sensitivity of ZnSnO3 sample at HT (>200 °C). When x is 0.1, the resulting ZA0.1SO sample is more sensitive to 500 ppm ethanol than other samples, with a response value of 336.0 at 260 °C. After decoration of 10 wt% nano-TiO2, the operating temperature of the ZA0.1SO sample under 385 nm UV illumination is greatly decreased from 260 to 110 °C, with a high ethanol response of 231.4 at the same concentration. The effects of Al-doping and nano-TiO2 decoration on the gas-sensing properties of the pristine ZnSnO3 sample were discussed based on the structure analysis and UV absorption of the sensitive materials.