Su8010

The phase analysis was conducted by X-ray diffraction (XRD) on a Bruker D8 Advance diffractometer employing Cu K_α irradiation with 40 kV and 50 mA. The observations of nanostructures and morphologies were conducted using a field-emission transmission electron microscope (STEM, Talos F200X G2) and a field-emission scanning electron microscope (SEM, SU8010), respectively. The elements of the samples were identified via energy dispersive X-ray spectroscopy (EDS), which was connected with STEM. The chemical composition was examined by X-ray photoelectron spectroscopy (XPS, VG Multilab 2000). The Brunauer–Emmett–Teller (BET) specific surface areas were determined through nitrogen adsorption isotherms at 373 K using a Micromeritics ASAP 2020 instrument and calculated from the linear part of the BET plot. FT-IR spectra were recorded on a Nexus-470 spectrometer. UV-vis diffuse reflection spectra (DRS) were measured on a spectrophotometer (Cary 5000).

The number-average molecular weight (M_n) and molecular weight distribution of the synthesized PHEMA were analyzed by Gel Permeation Chromatograph(GPC, Waters 1515) equipped with a refractive-index detector (Waters 2414) using HR column (7.8 × 300 mm). The FT-IR spectra measurements were performed on a Nicolet is 50 (Thermo Fisher Nicolet, United States) Fourier transform infrared spectrometer equipped with Thermo Nicolet corporation OMINIC 32 software. The ¹H NMR spectrum of the PHEMA was performed via INOVA 400 MHz nuclear magnetic resonance instrument with DMSO-d₆ as solvent and tetramethylsilane (TMS) as internal standard. Thermogravimetric analysis (TGA) was performed on a NETZSCH STA409PC instrument. The morphology of the GO and PHEMA/GO were characterized via a scanning electron microscopy (SEM, BRUKER SU8010) and transmission electron microscopy (TEM, JEOL JEM-1230, Japan). The CHI 660C electrochemical workstation (CH Instruments, Shanghai) with traditional three-electrode system was used to carried out the square wave voltammetry (SWV). While Ag/AgCl and platinum wire were used as reference and counter electrodes, glassy carbon electrode was used as a working electrode.