Manipulating spin polarization by <i>in-situ</i> reconstructed amorphous/crystalline CoFe-LDH for efficient electrocatalytic water splitting
Cheng Gong, Weixin Li, Xing Du, Xuan He, Daheng Wang, Hui Chen, Wei Fang, Lei Zhao, Yang Chai
Abstract
The performance of oxygen electrocatalysis is dependent on spin-related electron transfer behavior and orbital interactions. Herein, we report a simple spin-polarized approach to enhance the OER process of CoFe-LDH. The amorphous/crystalline CoFe-LDH nanosheets (a/c-CoFe-LDH) are prepared via acid-etching assisted co-precipitation to construct abundant amorphous/crystalline interfaces. The a/c-CoFe-LDH with controlled amorphous degree leads to manipulable magnetism, thus altering symmetric distribution of the d-orbital spin-electron states and facilitating spin-selective electron transfer process. The adsorbed O species will predominantly settle on a fixed spin direction, which propels the production of triplet oxygen. As the result, the amorphous/crystalline heterostructure contributes to suitable d-band centers, thus optimizing the adsorption strengths of oxygen-generated intermediates. Besides, the unsaturated coordination metals induce the generation of oxygen non-bonding states thus prompting oxygen as the redox center, thus triggering the lattice oxidation mechanism (LOM). Meanwhile, the crystalline structure endows excellent intrinsic conductivity and persistent stability. The obtained a/c-CoFe-LDH achieves low overpotentials of 269 mV at 10 mA cm<sup>-2</sup> in 1.0 M KOH towards the OER. To further enhance HER performance, Pt nanocluster was introduced into a/c-CoFe-LDH. This study offers a controllable method to prepare amorphous/crystalline electrocatalysts with regulated spin configuration for efficient water splitting.