Trivalent Cation Defect Optimization Spin State of Nickel(II) in NiFe-Layered Double Hydroxide Nanosheets for Oxygen Evolution

The defects have been confirmed to activate catalytic sites and significantly enhance electrocatalytic activity. However, the influence of defects on the electronic spin state of catalytic active sites and their impact on catalytic behavior are still in the early stages of research. Spin behavior is a fundamental property of the electrons. Herein, using NiFe-LDH nanosheets as the model structure, we constructed trivalent cation vacancy models to gain a deeper understanding of the intrinsic relationship among defects, spin, and catalytic activity from the perspective of the electronic spin state. The presence of defects leads to an increased proportion of the dz2 orbital perpendicular to the plane and the dxy orbital parallel to the LDH layer, which enhancement effectively improves the capture of out-of-plane oxygen intermediates and facilitates electron transfer within the plane. As a result, the catalytic activity for the oxygen evolution reaction (OER) is greatly improved. In addition, magnetic field experiments may also be used to better understand the role of spin in the catalytic process. With the increase of defect concentration, the spin-magnetic response intensity of the OER can be effectively enhanced, which is related to the defect-induced spin single electron. This work explains how defects can effectively modulate the electron spin properties of active centers, thereby achieving enhanced catalytic reaction kinetics. By shedding light on the principles governing catalytic sites at the electron spin level, we would aid in the understanding and design of catalysts at the spintronic level.