Keggin-Type Aluminum Polyoxometalate-Mediated Oxidation of Amorphous Carbon for Engineered Electrochemical Interfaces

Abstract

Amorphous carbon is widely used in energy storage and semiconductor technologies, where surface chemistry critically affects wettability, ion transport, and charge transfer. However, controlling surface oxidation remains challenging, as conventional oxidants indiscriminately modify carbon, degrading the framework and compromising performance. Here, we demonstrate a molecular-level approach to selectively oxidize sp²-rich domains of amorphous carbon using Keggin-type aluminum polyoxometalate (Al-POM)-coated silica nanoparticles. The positively charged Al₁₃(OH)₃₂⁷⁺ clusters electrostatically interact with sp² domains and release protons during structural transitions, facilitating proton-coupled oxidation with lower activation energy. This process introduces oxygen-containing groups, enhances interfacial charge transfer, and preserves the carbon framework. Our findings establish Al-POM-coated silica as a molecularly designed strategy for tailoring amorphous carbon interfaces, offering improved performance in both energy and semiconductor applications.

Keywords

amorphous carbon / electrochemical devices / hard mask / Keggin structure / polyoxometalate / redox reaction

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