Electrostatic Attraction of Cationic Carbon Quantum Dots Regulates Palladium Nanocrystal Distribution for Enhanced Ethanol Oxidation

Abstract Cationic carbon quantum dots (CQD) produced by thermal polymerization of citric acid with an ionic liquid exhibit a unique synergy of electrostatic anchoring, hydrogen-bond enrichment, and electronic modulation. In this study, the electrostatic attraction between cationic CQD and the chloropalladate precursor is exploited to significantly enhance the dispersion and density of palladium nanocrystals (Pd NCs). Meanwhile, the functional groups and defect sites on the CQD establish strong metal-support interactions with the Pd NCs, which modulate the electronic state of Pd, weaken the adsorption of toxic intermediates generated during ethanol oxidation reaction (EOR), thereby enhancing the anti-poisoning ability and durability of the catalyst. Furthermore, the oxygen- and nitrogen-containing functional groups on the CQD can form strong hydrogen bonds with ethanol molecules and the reduced graphene oxide (RGO) support, enriching ethanol molecules on the catalyst surface and creating a unique reaction microenvironment that facilitates the EOR. By synergistically modulating electrostatic attraction and the microenvironment, the obtained catalyst (Pd/CQD-RGO) is strategically designed in this work, which exhibits outstanding anti-poisoning capability and catalytic performance (3234.3 mA mg–1, 8.1 mA cm–2) in the EOR, providing a theoretical basis and practical reference for the rational design of carbon-based composite catalysts and their applications in energy conversion.