Novel self-cleaning electrode developed for alkaline-earth metal peroxide synthesis

Metal peroxide (MO₂, M=Ca, Sr, Ba) is an alternative to hydrogen peroxide (H₂O₂). It has excellent oxidative properties, superior chemical stability, high purity, and is easy to store and transport. It has been widely used in wastewater treatment and disinfection.

A Chinese research group has developed a novel self-cleaning electrode by constructing a micro-/nanostructure of a highly active catalyst with appropriate surface modification, achieving highly stable synthesis of alkaline-earth MO₂. Their study is published in Nature Nanotechnology.

The current primary synthesis process of MO₂ involves fast decomposition of H₂O₂, leading to insufficient utilization of H₂O₂.

In this study, led by Prof. Lu Zhiyi at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences, in collaboration with Prof. Jia Jinping at Shanghai Jiaotong University, the researchers proposed an in situ electrochemical synthesis process to lessen economic losses and reduce explosion risks arising from H₂O₂ transportation and storage.

High-concentration H₂O₂ generated by two-electron electrochemical oxygen reduction (2e^– ORR) can be efficiently converted into MO₂ on the electrode surface. However, severe adhesion of solid MO₂ product to the electrode surface can directly shut down the system.

To reduce surface adhesion, the research group constructed a Ni-doped oxygenated carbon electrode with Teflon coating (T-NiOC) as well as a micro-/nanostructure and low surface energy. This greatly reduced the solid–liquid contact area, facilitating rapid detachment of in situ generated MO₂ from the self-cleaning electrode surface.

The T-NiOC electrode showed accumulated selectivity of ~99% and stability for more than 1,000 hours at a current density of 50 mA cm^-2 for electrochemical synthesis of MO₂, thus demonstrating broad application potential.

Compared with H₂O₂, as-synthesized CaO₂ performed better in tetracycline degradation with hydrodynamic cavitation (HC).

This work could help pioneer and revolutionize other electrochemical solid-state synthesis reactions.