Bioinspired trimesic acid anchored electrocatalysts with unique static and dynamic compatibility for enhanced water oxidation

Characterization The crystalline structure of the fabricated samples was characterized by X-ray diffraction (XRD, Philips X-Pert diffractometer) with Cu Kα radiation. The morphology and structure were investigated by field-emission scanning electron microscopy (FE-SEM, Hitachi S-480 equipped with an energy dispersive X-ray spectrometer), and high-resolution Transmission electron microscopy (HRTEM, JEM-2100F microscope with Cs-corrector). The surface composition was investigated using X-ray photoelectron spectroscopy (XPS, a Thermo Fisher K-alpha 250Xi). Fourier transform infrared spectra (FTIR) was performed on a Shimadzu IRTracer-100 using the attenuated total reflection (ATR) infrared mode. The dissolved metal ions in OER electrolyte were measured by inductively coupled plasma massspectrometry (ICP-MS, Agilent 7700E). Raman spectra were measured by DXR Microscope (HORIBA HR Evolution). Contact angles of ultrapure water on as-prepared electrodes were analyzed via a dynamic contact angle determinator (JC2000C1) at room temperature. The bubble adhesion and desorption behaviors on the surfaces of composite electrodes were observed by Axioplan2 imagingE coupled with CHI 660E electrochemistry workstation Electrochemical Measurements Electrochemical measurements were tested on CHI 660E electrochemistry workstation in alkaline medium (1 M KOH) using a traditional three electrode configuration. Electrochemical measurements at large current densities were carried out on a workstation with KA3005P programmable DC power supply. Linear sweep voltammetry (LSV) was measured at a scan rate of 5 mV s-1 with 90% iR compensation unless otherwise stated. The slopes of the curves were calculated by the Tafel equation: η = b × log (j/j0). The electrochemical impedance spectroscopy (EIS) analysis were conducted with a frequency range of 105-0.01 Hz. The CV curves are obtained at the range of 1.183 to 1.233 V vs. RHE. ECSA was determined by the double layer capacitance (Cdl). Potentials described in this work were calibrated with the reversible hydrogen electrode (RHE), according to Nernst equation: E(RHE) = E(Ag/AgCl) + 0.0591 × pH + 0.197.