Merlin compact

The phase structure analysis of the samples was performed by powder X-ray diffraction (XRD, Bruker D8, Cu-Kα1 radiation, λ = 1.5418 Å) in the 2θ range of 10–90°. The actual Ag contents in Ag/In₂O₃ samples were measured by using an inductively coupled plasma optical emission spectrometer (ICP-OES, Agilent ICP-OES 725 ES). The morphology and microstructure of the samples were characterized by scanning electron microscope (SEM, Merlin Compact) and transmission electron microscope (TEM, JEOL JEM 2100 F). The chemical composition and surface state of the materials were analyzed by X-ray photoelectron spectroscopy (XPS, Thermo SCIENTIFIC ESCALAB 250Xi). The binding energy of elements is calibrated with the surface adventitious carbon (the C 1s peak at 284.8 eV). The porosity and specific surface area of the samples were measured by N₂ adsorption/desorption instrument (Micromeritics ASAP 2020).

The morphology of the CVD graphene obtained by scanning electron microscopy (SEM; Carl Zeiss MERLIN Compact, Germany), transmission electron microscopy (TEM; JEOL JEM-2100, Japan) and atomic force microscopy (AFM; Agilent 5500, U.S.) measurements, respectively. Sample treatment for AFM measurement: The graphene/Ta wire electrode was immersed in ethanol and sonicated in an ultrasonic bath for 48 h (600 W/40 kHz). During this time, a small amount of graphene sheet was peeled off and dispersed in ethanol. The graphene/ethanol solution was then sprayed onto the Si wafer and dried. The Raman spectrum of graphene was recorded on a Renishaw Raman microscope with an excitation laser wavelength at 532 nm. X-ray diffraction (XRD) spectra were created using a Rigaku Ultima IV x-ray diffractometer with CuK_α radiation (wavelength of 0.15406 nm).
The electrochemical performance was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) with a CHI 660E electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.). In a three-electrode system, a graphene/Ta wire electrode/or other sample electrodes, a platinum (Pt) sheet and a saturated calomel electrode (SCE) served as the working electrode, counter electrode, and reference electrode, respectively (Fig. 1a).

Morphology of samples was observed by scanning electron microscope (SEM, ZEISS, Merlin Compact), transmission electron microscopy (TEM, JEOL, JEM-2010F, 200 kV), and spherical correction transmission electron microscope (sc-TEM, JEOL, JEM ARM 200 F, 200 kV). Surface states of the samples were analysed by X-Ray diffraction (XRD, D/max-2500/PC, Rigaku) with Cu Kα radiation (λ = 0.15406 nm) operated at 40 kV and 150 mA. Raman spectra were collected in the range of 200–800 cm⁻¹ with an excitation wavelength of 532 nm (Horiba-iHR550) and X-ray photoelectron spectroscopy (XPS, Thermo Fisher, Escalab 250Xi, Al Kα) was carried out in the range of 0 to 1350 eV at a step of 1 eV. Thermogravimetry (TG, TA INSTRUMENTS, Q5000IR) was performed from 25 to 700 °C in air with a heating rate of 10 °C min⁻¹. The temperature of CNT matrix was measured by an infrared thermometer (Optrics, PI640).