Carbon nanodot precursors enable ultrahigh-loading copper single-atom catalysts for oxygen reduction reaction

Authors

• Prakhar Sharma, University of Kentucky
• Ayanthi Thisera, University of Kentucky
• Matthew G. Boebinger, Oak Ridge National Laboratory
• Jenna K. Rector, University of Kentucky
• Jason M. Unrine, University of KentuckyFollow
• Beth S. Guiton, University of KentuckyFollow
• Doo Young Kim, University of KentuckyFollow

Abstract

Single-atom catalysts (SACs) have attracted significant attention in electrocatalysis due to their high metal utilization and tunable electronic structures; however, their practical implementation is often limited by poor atomic dispersion, low metal loadings (typically < 1 wt%), and insufficient anchoring of single metal atoms on catalyst supports. Herein, we report a simple and versatile strategy to synthesize copper single-atom catalysts (Cu-SACs) with ultrahigh metal loading using citric-acid-derived carbon nanodots as metal-capturing precursors. Through hydrothermal treatment followed by pyrolysis in the presence of urea, atomically dispersed copper atoms coordinated with nitrogen are incorporated into a carbon framework, achieving a Cu loading of up to 20 wt% while maintaining atomic dispersion. Notably, a significant fraction of the copper single atoms exists as Cu⁺–N₂ coordination, which provides under-coordinated and catalytically active sites. The resulting Cu-SAC exhibits promising oxygen reduction reaction (ORR) activity in alkaline media, delivering a limiting current density comparable to that of commercial 20 wt% Pt/C with a predominant four-electron reduction pathway. Despite this high intrinsic activity, durability tests reveal gradual performance degradation under prolonged electrochemical operation, which is attributed to demetallation and aggregation of copper single atoms into metallic nanoparticles. These results demonstrate the potential of carbon nanodot-based platforms for synthesizing high-loading SACs, while underscoring the critical need to simultaneously control carbon porosity and metal–nitrogen coordination to enhance active-site accessibility and durability.

Document Type

Article

Publication Date

1-1-2026

Notes/Citation Information

Publisher Copyright: This journal is © The Royal Society of Chemistry, 2026.

Digital Object Identifier (DOI)

10.1039/d6ra01912a

Archival?

Archival

Repository Citation

Sharma, Prakhar; Thisera, Ayanthi; Boebinger, Matthew G.; Rector, Jenna K.; Unrine, Jason M.; Guiton, Beth S.; and Kim, Doo Young, "Carbon nanodot precursors enable ultrahigh-loading copper single-atom catalysts for oxygen reduction reaction" (2026). Plant and Soil Sciences Faculty Publications. 210.
https://uknowledge.uky.edu/pss_facpub/210