Electrochemical controlled synthesis and characterization of well-aligned IrO2 nanotube arrays with enhanced electrocatalytic activity toward oxygen evolution reaction

A novel template-assisted deposition and etching strategy is proposed in this paper for preparing IrO2 nanotube arrays on ITO substrates, i.e., electrodepositing IrO2 nanoparticles onto ZnO nanorod surfaces to produce IrO2-coated core–shell nanorod arrays, and followed by wet chemical etching the ZnO nanorods away to generate IrO2 nanotube arrays. Well-aligned IrO2 nanotube arrays with high purity and uniform size are produced by using this synthetic strategy. Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) are employed to examine the morphology, fine structure and composition of the IrO2 nanotube arrays intensively. Furthermore, electrocatalytic water oxidization experiments are performed to assess the catalytic performance of the as-prepared IrO2 nanotube arrays toward oxygen evolution reaction (OER). The IrO2 nanotube arrays have been found to possess an excellent catalytic performance: high turnover frequency (3.3 s−1 for TOF at 1.2 V versus Ag/AgCl), low oxygen evolution overpotential (η = 0.15 V) and good catalytic stability (55% catalytic activity remaining after undergoing 400 times potential cycles).