Multi-Metal Oxide Catalyst for Electrochemical Oxidation of Organic Pollutants
Authors: Mirehbar Keyvan , Sanchez Jaime Sanchez , Lado Julio J. , Palma Jesus 
Published: February 2024

In recent years, there has been a growing interest in developing highly efficient and stable catalysts for the electro-oxidation of water. These catalysts, besides water electrolysis, could be also a good alternative for removing organic pollutants from water by electro-degradation. Among the innovative groups of catalysts that have been investigated for this purpose, multi-metal oxides have been extensively studied for water electrolysis, but rarely for the direct or indirect oxidation of organic pollutants from water.1 Multi-metal oxide catalysts are composed of two or more metal cations that are chemically bonded to oxygen ions. The combination of different metal cations in a single oxide structure can lead to synergistic effects, which can enhance the catalytic activity and stability of the material. Several types of multi-metal oxide catalysts have been investigated for the electro-oxidation of water, including perovskite oxides, spinel oxides, layered double hydroxides, and mixed metal oxides. Perovskite oxides are a popular class of multi-metal oxide catalysts, which exhibit a wide range of interesting properties, including high catalytic activity, ionic and electronic conductivity, and thermal stability. These properties make perovskite oxides attractive materials for applications in various fields, such as environmental remediation.2 Additionally, the properties of perovskite oxides can be fine-tuned by doping or modifying their chemical composition, morphology, and crystal structure leading to the development of new materials with tailored properties.

In this work, multi-metal oxide (perovskite) nanoparticles were synthesized by the hydrothermal method by adjusting the pressure and temperature to obtain multi-metal oxides with controlled crystallinity and morphology. The synthesis was successfully scaled up and electrodes were prepared by impregnating 3D supports with the active materials. The electrocatalytic activity of the prepared electrodes was analyzed by physical and electrochemical characterizations. Moreover, to evaluate the potential application of multi-metal oxide electrodes for organic pollutants removal, phenol was selected as the target pollutant. To complete the research, the effect of different operational conditions (current density, initial pH, initial phenol concentration, and flow rate) on the COD removal of the wastewater in the divided flow cell configuration was investigated. Furthermore, the removal pathway was studied using GC/MS.

Acknowledgment:

This project has received funding through the HYSOLCHEM project (grant agreement No. 101017928) from the European Union’s Horizon 2020 research and innovation programme.

References:

(1) Kim, J. S.; Kim, B.; Kim, H.; Kang, K. Recent Progress on Multimetal Oxide Catalysts for the Oxygen Evolution Reaction. Adv. Energy Mater.
2018, 8 (11), 1702774. https://doi.org/10.1002/aenm.201702774.

(2) Kumar, A.; Kumar, A.; Krishnan, V. Perovskite Oxide Based Materials for Energy and Environment-Oriented Photocatalysis. ACS Catal.
2020, 10 (17), 10253–10315. https://doi.org/10.1021/acscatal.0c02947.