第八课堂测试：阅读理解Porous carbon microspheres (PCMSs) were prepared by ultrasonic spray pyrolysis and attached with microwires composed of carbon fibre paper after the dip and dry method (Fig. 2a,b and Supplementary Figs S1 and S2). The loading of the PCMSs was confirmed by scanning electron microscopic images of the carbon fibre paper microwires before and after the dip and dry process (inset of Fig. 2b and Supplementary Fig. S3). These images show the pores on the spherical surface of amorphous PCMS and its attachment with conductive microwires. X-ray diffraction patterns of the PCMSs and the microwires are shown in Supplementary Fig. S4. A high resolution transmission electron microscopic image shows diffracted fringes of the microwire’s cross-section (inset of Fig. 2c). The transmission electron microscopic images of the PCMS reflect void spaces (Fig. 2c and Supplementary Fig. S5), which were introduced after removal of the LiCl salt during synthesis. The specific surface area and pore size distribution of the PCMSs before the dip and dry step were tested by nitrogen adsorption-desorption measurements. The resulting isotherm (Fig. 2d) shows a hysteresis loop that is typical for mesoporous materials at high relative pressures. Its specific surface area, calculated by the Brunauer–Emmett–Teller method, was 910 m2 g-1. The pore size distribution, derived from the adsorption branch of the isotherm, is broad at ~20nm (inset of Fig. 2d). Surface functional groups of the PCMSs were detected by Fourier transform infrared spectroscopy and energy dispersive spectroscopy (EDS), and the results are shown in Supplementary Figs S6 and S7b, respectively. They were also evaluated by X-ray photoelectron spectroscopy (Fig. 2e). Quantitative analysis shows (Fig. 2f) two types of surface functional groups, C=O carbonyl group at 532 eV with the dominant percentage of 78% and C-OH at 530.8 eV with a percentage of 22%. The inset in Fig. 2f contains the results of the elemental analysis of PCMSs, which were found to have 10% oxygen in 0.1 g of the PCMSs.1. How many characterizing technologies were used?A: 5 B: 6 C: 7 D: 8