Synthesis of novel heteroatom-rich bis-Schiff base for enhancing performance of multi-walled carbon nanotube/polyaniline nanocatalyst in oxygen evolution reaction

Abstract

Fabrication of oxygen evolution electrocatalysts with high performance and endurance is of interest for the electrolysis of water. To date, several compounds have been introduced to achieve it but the idea of using bis-Schiff base with conductive materials/noble metal may be a thoughtful strategy. Herein, bis-Schiff base of 6,6′ ((oxybis(4,1phenylene)) bis (azanylylidene)) bis (methanylylidene) bis (3-(2-(2- hydroxyethoxy) ethoxy) phenol) (HBIEP) was prepared and used as a modifier for the preparation of an electrocatalyst. A highly efficient electrocatalyst is reported based on HBIEP deposited on Au nanoparticles (NPs) and hollow hierarchical polyaniline (PANI) nanorod/multi-walled carbon nanotube (MWCNT) to accelerate the electron transfer rate and enhance the chemical stability for oxygen evolution reaction (OER). The MWCNT/PANI/HBIEP/Au exhibits high current density for OER at low overpotential and provides low Tafel slope of 35 mV dec−1 and remarkable stability during 50 h. Electrochemical impedance spectroscopy showed that in comparison to MWCNT/PANI, the presence of both AuNPs and HBIEP can further facilitate the charge transfer and improve the performance of the electrocatalyst for OER. Although MWCNT/PANI/Au presents proper performance, HBIEP enhances its efficiency and stability during OER. The suitable functionality of the electrocatalyst comes from its electronic structure and large active sites which improved in the presence of bis-Schiff base.