Tuning the oxygen defects and Fermi levels via In3+ doping in SnO2-In2O3 nanocomposite for efficient CO detection

In this work, In3+ doping SnO2-In2O3 nanocomposites were successfully synthesized via sol-gel method and grinding-annealing method. The structure and morphology of nanocomposites were characterized by XRD, FESEM and TEM. In3+ doping SnO2-In2O3 nanocomposites exhibited superior gas-sensing performance compared to pristine SnO2 and SnO2-In2O3 nanocomposite. Among these materials, the 8 mol% In3+ doping SnO2-In2O3 nanocomposite (40ISI(0.08)O(2) the mole ratio of Sn0.02In0.08O2 to In2O3 is 3:1) showed a higher baseline resistance, the highest response value and fast response speed. Specifically, the response value of 40ISI(0.08)O reached 9 toward 1000 ppm CO, which was over 3.2 times higher than that of pristine SnO2, and the response time was 15 s. The possible gas sensing mechanism was illustrated based on the results of XPS, UV-Vis DRS, room temperature PL spectra and BET test. By In3+ doping modification, the band gap of Sn0.02In0.08O2 (SI0.08O) became narrow, and the Fermi level shifted by 0.33 eV toward the valance band. The superior gas sensing properties of 40ISI(0.08)O were mainly attributed to the synergistic effect of the introduction of more oxygen defects, the modulation of Fermi levels and the large specific surface area of SI0.08O.

Automated summary

In3+-doped SnO2-In2O3 nanocomposites were successfully synthesized and characterized. Compared to the pristine SnO2 and SnO2-In2O3 nanocomposite, the doped nanocomposites exhibited superior gas-sensing performance. Among them, the 8 mol% In3+ doping SnO2-In2O3 nanocomposite showed the highest response value and fast response speed.