Oxygen-Reconstituted Active Species of Single-Atom Cu Catalysts for Oxygen Reduction Reaction

Liu Yang,Dapeng Cao,Daojian Cheng,Haoxiang Xu,Rui Cao,Lirong Zheng,Xiaofei Zeng,Huibing Liu,Yan Huang

doi:10.34133/2020/7593023

Abstract

Identification of an active center of catalysts under realistic working conditions of oxygen reduction reaction (ORR) still remains a great challenge and unclear. Herein, we synthesize the Cu single atom embedded on nitrogen-doped graphene-like matrix electrocatalyst (abbreviated as SA-Cu/NG). The results show that SA-Cu/NG possesses a higher ORR capability than 20% Pt/C at alkaline solution while the inferior activity to 20% Pt/C at acidic medium. Based on the experiment and simulation calculation, we identify the atomic structure of Cu-N2C2 in SA-Cu/NG and for the first time unravels that the oxygen-reconstituted Cu-N2C2-O structure is really the active species of alkaline ORR, while the oxygen reconstitution does not happen at acidic medium. The finding of oxygen-reconstituted active species of SA-Cu/NG at alkaline media successfully unveils the bottleneck puzzle of why the performance of ORR catalysts at alkaline solution is better than that at acidic media, which provides new physical insight into the development of new ORR catalysts.

Highlights

When energy consumption is rapidly rising, the resulting environmental issues have become serious [1]
Based on the XAS and the systematic search for possible configurations by density functional theory (DFT) calculations, we identified the atomic structure of the CuN2C2 moiety embedded in porous graphene-like nanosheets for SA-Cu/NG
We found that the reconstitution of active species of Cu-N2C2 under Oxygen reduction reaction (ORR) working condition was induced by dynamic adsorption of atomic oxygen (O∗) intermediate on the CuC site, and the oxygenreconstituted Cu-N2C2-O structure is the real active species of SA-Cu/NG for ORR at alkaline condition

Summary

Introduction

When energy consumption is rapidly rising, the resulting environmental issues have become serious [1]. Some useful strategies have been developed to synthesize the Cu-SACs trapped on nitrogen-rich porous carbon with large-scale or high load contents [29,30,31] These studies have shown that the Cu-SACs possess high ORR activity, the critical question of “what are the realistic active sites of Cu-SACs for ORR?” is unclear yet and in dispute. Identification of the definite active-site structure and thermodynamics intermediate transformation on Cu-N-C catalysts under ORR working conditions are required urgently, which is significantly important for intelligent fabrication of fresh ORR SACs. we use the surfactant-assisted synthesis method to successfully prepare the single-atom Cu embedded on an N-doped graphene-like matrix (abbreviated as SA-Cu/NG). The finding of oxygenreconstituted active species at alkaline media unveils the bottleneck puzzle of why the activity of the ORR catalyst at alkaline condition is always superior to the one at acidic solution

Results and Discussion

Conclusions

Materials and Methods

Conflicts of Interest