Synthesis of ultrathin iron doped cobalt-based hydroxide nanosheets with massive defects for enhanced water oxidation electrocatalysis

• Main Author: Yuen, Wei Juan
• Other Authors: Alex Yan Qingyu
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/139527
• Institution: Nanyang Technological University

The challenges of the increasing energy consumption and global warming have prompted scientific exploration into the electrocatalytic water splitting process, in which the oxygen evolution reaction (OER), plays a vital role. The development of inexpensive electrocatalysts that can reduce the high overpotential of OER process has long been the crucial challenges for practical applications. In recent years, extensive research and studies have been conducted on non-noble cobalt (Co)-based materials (such as oxides and (oxy)hydroxides) as OER electrocatalysts owing to their inherent electrochemical capabilities and structural adjustability. However, the electrocatalytic activity of Co-based electrocatalysts toward OER is still far from the practical demands because of their finite number of exposed active sites. To tackle this problem, we developed a facile and efficient method to synthesize iron doped Co-based (oxy)hydroxides with massive defects for enhanced elctrocatalysis. The as-prepared samples are characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and linear sweep voltammetry (LSV) analysis. The experimental data obtained shows iron doped Co-based (oxy)hydroxides having a wrinkled and porous nanosheet morphology with lateral size ranging between 200-400 nm. These iron doped Co-based (oxy)hydroxides that are being synthesized exhibited significantly improved electrocatalytic activity as compared to the ones that are non-doped. Specifically, a small overpotential of only 230 mV is required to obtain a current density of 10 mA cm−2 for iron doped Co-based (oxy)hydroxides with a low Tafel slope of 48.8 mV dec−1, which is a significant decrease from those of non-doped Co-based (oxy)hydroxides (330 mV and 62.5 mV dec−1) and state-of-the-art commercial RuO2 (325 mV and 118.8 mV dec−1). This work opens up a new promising approach to rational design of functional OER electrocatalysts that can be used in energy-related devices even in a large global scale.