Synthesis and characterization of new nanocomposite based on di-substituted Keggin- type phosphotungstate@ceramic as a new and high-performance nanocatalyst for O2 evolution from water oxidation reaction

In this research, a new nanocomposite was synthesized via the sol-gel method by covalent immobilizing of di-substituted Keggin-type heteropolyanion containing cobalt (PW10Co2) on the surface of manganese oxide (MnO2) ceramic. The desired nanocomposite (PW10-Co2@MnO2) was used as an effective heterogeneous catalyst in the water oxidation reaction for oxygen evolution. The PW10Co2@MnO2 nanocatalyst was identified through Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) methods in detail. After confirming the preparation of the PW10Co2@MnO2, its catalytic activity in the water split-ting reaction was assessed in the presence of cerium (IV) ammonium nitrate (CAN) as an efficient oxidant at different pH (pH = 7 and 9). The PW10Co2@MnO2 nanocatalyst demonstrated turnover number (TON), turnover frequency (TOF), and O2 evolution of 520.12 mmolO2 molCo:s, 178 mmolO2molCo, and 0.003 mgO2L:S, respectively, which are the highest values at pH = 9 in the water oxidation process. Moreover, the effect of CAN concentration, pH, and the amount of KOH was assessed on the catalytic activity, and a plausible reaction mechanism was proposed. In the present study, the PW10Co2@MnO2 nanocatalyst provides valuable insights into the design of other catalysts for the water oxidation reaction and beyond. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.