D-orbital Reconstruction Achieves Low Charge Overpotential in Li-oxygen Batteries.

Zhou, Yin; Yin, Kun; Huang, Yingying; Li, Jiapei; Zhu, Anquan; Lin, Dewu; Gan, Guoqiang; Zhang, Jianfang et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Charge overpotential for oxygen evolution reaction is a crucial parameter for the energy conversion efficiency of lithium-oxygen (Li-O<sub>2</sub>) batteries. So far, the realization of low charge overpotential via catalyst design is a grand challenge in this field, which usually exceeds 0.25 V. Herein, we report an orbital reconstruction strategy to significantly decrease the charge overpotential to the low 0.11 V by employing PdCo nanosheet catalyst under a low-loading mass (0.3 mg/cm<sup>2</sup>) and capacity (0.3 mAh/cm<sup>2</sup>). Experimental and theoretical calculations demonstrate that the precise d-d orbital coupling (d<sub>xz</sub>-d<sub>xz</sub>, d<sub>yz</sub>-d<sub>yz</sub> and d<sub>z</sub><sup>2</sup>-d<sub>z</sub><sup>2</sup>) between the low-electronegativity Co and Pd leads to the reconstruction of Pd 4 d orbitals in PdCo nanosheets, thereby resulting in a downward shift of all the three active Pd 4 d orbitals (d<sub>z</sub><sup>2</sup>, d<sub>xz</sub> and d<sub>yz</sub>) relative to that of Pd nanosheets. Furthermore, the highest energy level of the Pd 4d<sub>z</sub><sup>2</sup> orbital in PdCo is lower than the lowest energy levels of the Pd 4d<sub>xz</sub> and 4d<sub>yz</sub> orbitals in pure Pd, significantly decreasing the charge activation energy and achieving a highest energy conversion efficiency of 91%. This finding provides the orbital-level tuning into rational design of highly efficient electrocatalysts for Li-O<sub>2</sub> batteries.