Smartlab 9 x

The crystallographic structures of bare AC and ALD oxides-coated AC electrodes were examined using a Rigaku Smartlab 9 X-ray diffractometer at a scan rate of 6°/min using 150 mA current, 40 kV voltage, and copper target. The surface morphology and particle size were characterized using a ZEISS Sigma−500 field emission scanning electron microscopy (FESEM). The elemental distribution and mapping were obtained using Energy Dispersive Spectroscopy (EDS, BRUKE XFlash−6130, Berlin, Germany). Transmission electron microscopy (TEM) images were captured on a JEM2100 instrument at an acceleration voltage of 200 kV to analyze the deposition features on the carbon surface. Quantachrome Autosorb-iQ2-MP (Quantachrome Instruments, Florida, USA) and nitrogen isotherms were used to test specific surface areas by BET tests with degassing at 250 °C for 3 h for each 36 mg sample. The DFT (density functional theory) and HK (Horvath-Kawazoe) methods from N2 adsorption-desorption isotherms (at 77.4 K) were employed to verify the surface area and porosity. The elemental distribution and functional changes were explored using X-ray photoelectron spectroscopy (Thermo Scientific ESCALAB 250Xi).

The crystalline phase was determined by powder X-ray diffraction (XRD) using a Rigaku SmartLab 9 X-ray diffractometer (Tokyo, Japan) with Cu Kα radiation (λ = 1.5418 Å). The morphology was characterized by a scanning electron microscopy (SEM, Zeiss Supra-40, Oberkochen, Germany) and transmission electron microscopy (TEM, FEI Talos F200x, Waltham, MA, USA). Element distribution mapping was carried out using an energy dispersive X-ray detector equipped on the FEI Talos F200x. X-ray photoelectron spectroscopy (XPS) was studied on a Thermo Fisher ESCLAB 250Xi spectrometer (Waltham, MA, USA).