Identification of Cu-N2 sites for Zn-air batteries in harsh electrolytes: from computer virtual screening to practical application

Abstract

Abstract Non-precious-metal catalysts possess promising potential to replace noble metals (e.g. Pt, Ru, Ir etc.) in broad catalytic areas; however the selection of efficient ones based on experimental results is extremely time-consuming and capital sensitive. Herein, we employ a computer-based method for virtual screening (VS) of chemical structures to discover new electrocatalysts via an efficient standard protocol. Specifically, we discovered a thermodynamically stable and highly active Cu-N2 Lewis acid site by combining molecular dynamics (MD) simulation, and density functional theory (DFT) calculations. The MD simulations rapidly screen out the structures that are both thermodynamically stable and stable in harsh electrolytes, while the DFT calculations filter out the ones with high overpotential by evaluating the adsorption energies for oxygen-related adsorption intermediates based on “Volcano plots” theory. The as-predicted Cu-N2 Lewis acid site was experimentally synthesized in a hollow nitrogen-doped octahedron carbon framework (Cu-N2@HNOC), in which an ultra-high loading of single Cu atoms (13.1 wt%, ICP-MS, the highest on record) is achieved. As a result, a flexible solid-state Zn-air battery was fabricated with Cu-N2@HNOC as the cathode catalyst that realized prolonged cycling, achieving a record high maximum power density of 78.1mW/cm2. Our strategy is widely applicable to seek valuable catalysts via VS for a wide range of applications, e.g. electrocatalysis, biocatalysis, and industrial catalysis, and suggests that the VS is more efficient than most experimental approaches.