Quasi-industrial Preparation of SWCNTs-confined High-entropy Oxides as Self-supported Electrodes for Continuous Electrosynthesis

Abstract

High-entropy oxides (HEOs) are emerging as highly promising materials for electrochemical applications due to their exceptional electronic properties and active sites. However, the synthesis of 1D HEO with high aspect ratios and mechanical properties has been challenging, particularly on an industrial scale. Herein, we report a spatially confined oxidation (SCO) method to synthesize 1D HEO@SWCNTs with high specific surface area and stability. This method enables the large-scale production of HEO@SWCNTs, achieving quasi-industrially quantities in a single batch, and can be extended to seven-element 1D HEO. The resulting exhibit a homogeneous distribution of elements and a single-phase solid solution structure, as confirmed by STEM-EDS and XRD analysis. The Fermi level of SWCNTs is downshifted into the valence band upon HEO doping, enhancing conductivity and electrochemical activity. The HEO@SWCNTs electrode demonstrates superior flexibility and self-supported properties, making it suitable for large-scale electrochemical applications. Chronoamperometric measurements reveal excellent stability, maintaining 94% current retention after 20 h. Notably, in the electrochemical epoxidation reaction cycloolefin, the HEO@SWCNTs self-supported electrode achieves an average FE of 70.7% for epoxy-cyclohexane over 24 h. This work provides a scalable and versatile approach to the synthesis of self-supported electrodes for advanced electrochemical systems.