Abstract
Single-atom catalysts are becoming increasingly significant to numerous energy conversion reactions. However, their rational design and construction remain quite challenging due to the poorly understood structure–function relationship. Here we demonstrate the dynamic behavior of CuN2C2 site during operando oxygen reduction reaction, revealing a substrate-strain tuned geometry distortion of active sites and its correlation with the activity. Our best CuN2C2 site, on carbon nanotube with 8 nm diameter, delivers a sixfold activity promotion relative to graphene. Density functional theory and X-ray absorption spectroscopy reveal that reasonable substrate strain allows the optimized distortion, where Cu bonds strongly with the oxygen species while maintaining intimate coordination with C/N atoms. The optimized distortion facilitates the electron transfer from Cu to the adsorbed O, greatly boosting the oxygen reduction activity. This work uncovers the structure–function relationship of single-atom catalysts in terms of carbon substrate, and provides guidance to their future design and activity promotion.
Highlights
Single-atom catalysts are becoming increasingly significant to numerous energy conversion reactions
Graphene and two representative sizes of carbon nanotube (CNT) with the diameter of 8 and 4 nm were utilized as the substrates, and the corresponding SACs are denoted as Cu/G, Cu/CNT-8, and Cu/CNT-4, respectively
In summary, using the single-atom Cu dispersed on different sp2hybridized carbon substrates as the model, we have demonstrated the operando substrate-related geometry distortion of single-atom CuN2C2 active site and its relationship with the oxygen reduction reaction (ORR) activity
Summary
Single-atom catalysts are becoming increasingly significant to numerous energy conversion reactions. For the RuN4 SACs catalyzing the oxygen evolution reaction, the adsorption of extra O is observed to induce the in situ reconstruction of active site, and the formed O-RuN4 moiety highly enhances the activity[5] These dynamic catalytic behaviors provide valuable information on the determination of active sites and the comprehension of reaction mechanism. We try to correlate the operando structure evolution of SACs to their catalytic properties, and demonstrate the substrate-induced activity enhancement of CuN2C2 SACs embedded within sp2-hybridized carbon frameworks. XAS indicate that the CuN2C2 active site is geometrically distorted during the ORR as a response to the newly coordinated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
