Substrate strain tunes operando geometric distortion and oxygen reduction activity of CuN2C2 single-atom sites

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.

Strain engineering in single-atom catalysts: GaPS4 for bifunctional oxygen reduction and evolution

“…† Recently, G. Han et al proposed bond angle deviation to explain the ORR catalytic activity of 2D CuN 2 C 2 . 26 Here, the local substrate geometry distortion under different biaxial strains was also evaluated. During the adsorption process, the biaxial strain can change the spatial position of the substrate atoms, thus changing the bond angles near the doped transition metal.…”

“…To enhance the catalytic activity, doping transition metal atoms into 2D materials have been widely used in electrocatalysis. [21][22][23][24] Moreover, physical and chemical properties of the 2D materials, such as d-band structure, adsorption energy, and catalytic activity, can be modulated by strain engineering, [25][26][27][28] triggering high catalytic action. For instance, strained NiFe-MOFs with 6% lattice expansion exhibit superior catalytic performance for the OER under alkaline conditions.…”

Tailoring the selectivity and activity of oxygen reduction by regulating the coordination environments of carbon-supported atomically dispersed metal sites

“…Yin and co-workers authentically demonstrated the substrate strain could tune geometry distortion of active sites and relevant ORR activity. 147 Reasonable substrate strain allowed the optimized distortion of Cu site bonding with the oxygen species, while maintaining the structure of the catalytic CuN 2 C 2 moiety and facilitating charge transfer from Cu to the adsorbed O. This innovative work uncovered the unusual substrate structure–function relationship of the C-ADMSs and put forward a new idea to optimize the intrinsic catalytic activity.…”

Low‐dimensional material supported single‐atom catalysts for electrochemical CO2 reduction

“…As mentioned in this review, a Pb 1 Cu nanosheet alloy catalyst is highly active for producing formate, but the active site originates from support Cu rather than isolated Pb atoms 66 . In addition, even for the carbon support, their structure also dramatically influences the electronic state of the active center, which affects the final catalytic activity of the SACs 172–174 . Considering the unique properties in LDMs, in this sense, more attention should be paid to identifying the role of the LD support during the ECR process, which may help the rational design of highly efficient LDM supported SACs. …”