Photothermal Annealing-Enabled Millisecond Synthesis of Carbon Nanoonions and Simultaneous Single-Atom Functionalization.

Jeon, Dogyeong; Shin, Hamin; Cha, Jun-Hwe; Kim, HongHui; Park, Seohak; Ahn, Jaewan; Cho, Su-Ho; Park, Chungseong et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Carbon nanoonions (CNOs), known for their nanometer-scale surface curvature and potential for versatile functionalization, are widely used in energy and environmental applications. However, they face challenges from energy-intensive synthesis and time-consuming post-treatments, resulting in low yields and poor-quality sp<sup>2</sup> shells, which limit their commercial viability. In this study, we introduce a direct-contact annealing (DCA) platform reaching up to 3030 K within 1.4 ms (2.2 × 10<sup>6</sup> K s<sup>-1</sup>), utilizing black-colored photothermal agents for millisecond-scale synthesis of CNO under ambient air. Moreover, we demonstrate simultaneous in situ single-atom catalyst (SACs) functionalization with eight different metal elements on the outer surface of CNOs. A case study on Pt SAC-functionalized CNOs demonstrates outstanding hydrogen evolution reaction performance. This DCA platform provides a promising alternative to conventional harsh conditions for SAC/CNO electrocatalyst synthesis, enabling ultrafast and facile production of surface-functionalized catalysts with exceptional energy efficiency and scalability advantages for advanced energy applications.