Paclitaxel After hydrothermal reaction, the product was washed with distilled water 4 times and ethanol 1 time by centrifuge and dried at 70 ��C for 24 h. The pure and additive-loaded In2O3 hollow spheres could be prepared by the heat treatment of the above products at 500 ��C for 2 h. For simplicity, hereinafter, the pure, Cu, Nb, Ni, Pd, Sb-loaded In2O3 hollow spheres after heat treatment will be referred as In2O3, Cu-In2O3, Nb-In2O3, Pd-In2O3, Ni-In2O3, and Sb-In2O3 specimens, respectively. The morphologies of the hollow spheres were analyzed by field-emission scanning electron microscopy (FE-SEM, S-4800, Hitachi Co. Ltd.).For the gas sensing measurement, 0.1 g of each prepared hollow sphere was dispersed in 10 mL of D.I. water and these solutions were deposited on the sensor substrate by using the drop-coating technique.
An alumina substrate (1.5 �� 1.5 mm2) with two Au electrodes on its top surface and a micro-heater on its bottom surface was used. The temperature of the sensors was controlled by modulating the power of the microheater underneath the substrate. The sensor temperature was measured to be 371 and 440 ��C at the heater powers of 400 and 500 mW, respectively, by an IR temperature sensor (Rayomatic 14814-2, Euroton IRtec Co.). The uncertainty of sensor temperature was ��5 ��C. The sensor was positioned in a specially designed quartz tube chamber and dry synthetic air and mixing gas were flowed into this chamber. The gas response (S = Ra/Rg, Ra: resistance in air, Rg: resistance in gas) to 500 ppm CH4, 100 ppm NH3, H2, CO, and 5 ppm of H2S were measured using a multimeter (Keithley K2000) which connected with a computer.
3.?Results and DiscussionAll the as-prepared specimens after hydrothermal reaction were spheres with a size of 5�C7 ��m (Figure 1). The surface morphology, the presence of nano-size particles, and the connectivity between carbon spheres were slightly different Cilengitide for each specimen according to the doping of additives. After heat treatment of the precursor spheres at 500 ��C for 2 h, the as-prepared precursor spheres with clean surfaces (Figure 1) were converted into spheres with rough surfaces consisting of primary nanoparticles (Figure 2).Figure 1.SEM images of as-prepared carbon spheres coated with In- and additive-precursors: In-PR (precursor spheres selleck chemical to be converted into In2O3 hollow spheres); M-In-PR (M = Sb, Cu, Nb, Pd, and Ni; precursor spheres to be converted into M-In2O3 hollow spheres).
…Figure 2.SEM images of In2O3, Sb-In2O3, Cu-In2O3, Nb-In2O3, Pd-In2O3 and Ni-In2O3 spheres after heat treatment at 500 ��C for 2 h.The average diameters of ~100 In2O3, Sb-In2O3, Cu-In2O3, Nb-In2O3, Pd-In2O3 and Ni-In2O3 spheres were 2.3 �� 0.5 ��m, 2.4 �� 0.7 ��m, 2.2 �� 0.4 ��m, 2.3 �� 0.6 ��m, 2.3 �� 0.5 ��m, and 2.2 �� 0.5 ��m, respectively.