Synthesis and enhanced formaldehyde gas-sensing performance of mesoporous SnO2 nanospheres doped with trivalent metal-cations

Mesoporous SnO2, Sn0.861Al0.186O2, Sn0.921In0.106O2 and Sn0.959La0.055O2 nanospheres were successfully synthesized by a one-step solvothermal method. The compositions, crystal structures, microstructures, morphology and gas-sensing performance of the as-synthesized Al-, In- and La-doped SnO2 nanospheres were characterized by XRD, EDS, TEM, SEM, FT-IR, UV–vis and BET. All samples present the similar mesoporous-structural nanospheres due to the same chemical synthesis conditions. The gas-sensing results indicate that the cations-doping greatly affects the formaldehyde gas-sensing performance, and the response increases with the increasing radius of Al, In and La. Owing to the higher specific surface area and larger La3+ radius, Sn0.959La0.055O2 sensor presents the best gas-sensing performance with the response value of 149.59 to formaldehyde gas at 200 °C. It is concluded that metal-cation doping not only causes lattice distortion to increase oxygen vacancies, but also could refine the crystalline grain to improve the specific surface area of metal-cations doped SnO2 nanospheres.