Direct Observation of Transition Metal Ions Evolving into Single Atoms: Formation and Transformation of Nanoparticle Intermediates. Issue 12 (2nd March 2023)

• Record Type: Journal Article
• Authors: Han, Zheng; Wang, Yi; Zheng, Jiming; Li, Ren; Jia, Boqian; Li, Dingding; Bai, Lei; Guo, Xuting; Zheng, Lirong; Bai, Jinbo; Leng, Kunyue; Qu, Yunteng
• Is Part Of: Advanced science. Volume 10:Issue 12(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-02
• Subjects: nanoparticles -- single atom catalysts -- transition metals; Science -- Periodicals; 505
• DOI: 10.1002/advs.202206166
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: Understanding the dynamical evolution from metal ions to single atoms is of great importance to the rational development of synthesis strategies for single atom catalysts (SACs) against metal sintering during pyrolysis. Herein, an in situ observation is disclosed that the formation of SACs is ascertained as a two‐step process. There is initially metal sintering into nanoparticles (NPs) (500–600 °C), followed by the conversion of NPs into metal single atoms (Fe, Co, Ni, Cu SAs) at higher temperature (700–800 °C). Theoretical calculations together with control experiments based on Cu unveil that the ion‐to‐NP conversion can arise from the carbon reduction, and NP‐to‐SA conversion being steered by generating more thermodynamically stable Cu‐N4 configuration instead of Cu NPs. Based on the evidenced mechanism, a two‐step pyrolysis strategy to access Cu SACs is developed, which exhibits excellent ORR performance. Abstract : Given the beneficial properties of single atom catalysts (SACs), understanding their evolution from metal ions is critical. This present work demonstrates the direct observation of transition metal ions evolving into SACs with a detailed explanation. Specifically, metals are aggregated into nanoparticles at lower temperatures (500–600 °C), and subsequently transformed into metal single atoms at higher temperatures (700–800 °C).