MOF-derived Pr-doped In2O3 hollow tubes rich in oxygen vacancies for enhancing the n-butanol sensing performance

Abstract

Pr-doped In₂O₃ (denoted as x at% Pr–In₂O₃, x represents the atomic percentage of Pr and In added) materials were derived from calcining Pr-doped indium based MOF synthesized using a solvothermal method. The 9.52 at% Pr–In₂O₃ gas sensor has a sensitive response (425), special selectivity, high humidity resistance (a high response of 201 at 80% RH), short response/recovery time (27 s/277 s) and long-term stability to 100 ppm (volume concentration in parts per billion) n-butanol at 260 °C. The excellent sensing performance of this sensor for n-butanol is attributed to the abundant oxygen vacancies generated by Pr doping into In₂O₃. The generation of oxygen vacancies is due to the lattice distortion caused by the different radii of Pr and In ions, and the charge compensation effect caused by the different valence states of Pr and In ions. Oxygen vacancies reduce the activation energy of the n-butanol reaction, provide active sites for gas molecules, narrow the bandgap width of semiconductor materials, improve the electron transfer efficiency, and allow more electrons to react with oxygen on the material surface, producing more chemisorbed oxygen (O⁻) for the n-butanol reaction. The ability of Pr³⁺/Pr⁴⁺ redox pairs to capture water molecules is the reason why the sensor has moisture resistance.