Kim, Hee-Eun Lee, In Hyuk Cho, Jinwon Shin, Sangyong Ham, Hyung Chul Kim, Jin Young Lee, Hyunjoo 2024-01-19T19:31:10Z 2024-01-19T19:31:10Z 2021-09-02 2019-09 2196-0216 https://pubs.kist.re.kr/handle/201004/119657 Single atom catalysts (SACs) maximize the utilization of noble metal whereas nanoparticle catalysts have inner metal atoms unavailable. In this study, various electrocatalytic reactions were investigated for Pd and Pt SACs. The single atoms were immobilized on thin layers of graphitic carbon nitride with carbon black (for simplicity, C@C3N4) to produce an electrochemically efficient and stable SACs. Single atomic structure was confirmed by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and extended X-ray absorption fine structure (EXAFS) analyses. Oxygen reduction reaction (ORR) and CO stripping experiments were conducted, and the results were compared with the corresponding nanoparticle catalysts. Lack of ensemble sites in the SACs resulted in two-electron pathway for ORR; single atomic Pd on C@C3N4 (C@C3N4-Pd-1) showed high activity and selectivity for H2O2 formation. DFT calculations showed that C@C3N4-Pd-1 follows a downhill path for H2O2 formation unlike single atomic Pt on C@C3N4 (C@C3N4-Pt-1), resulting in enhanced H2O2 selectivity. Weaker adsorption of oxygen intermediates on C@C3N4-Pd-1 resulted in enhanced ORR activity. The SACs showed no interaction with CO as confirmed by no CO stripping peak. This resulted in no activity for formic acid oxidation following indirect pathway or methanol oxidation, which necessitates COads as reaction intermediates. SACs can be efficient electrocatalysts with high activity and unique selectivity. English WILEY-V C H VERLAG GMBH Palladium Single-Atom Catalysts Supported on C@C3N4 for Electrochemical Reactions Article 10.1002/celc.201900772 1 CHEMELECTROCHEM, v.6, no.18, pp.4757 - 4764 CHEMELECTROCHEM 6 18 4757 4764 N scie scopus 000475249600001 2-s2.0-85068929279 Electrochemistry Electrochemistry Article GRAPHITIC CARBON NITRIDE OXYGEN REDUCTION REACTION FORMIC-ACID HYDROGEN ADSORPTION OXIDATION PERFORMANCE PHOTOCATALYST EVOLUTION METHANOL DESIGN single-atom catalysts electrocatalysts graphitic nitride palladium oxygen reduction reaction