A High-Entropy Engineering on Layered Double Hydroxide Electrocatalyst with Electronic Structure Reconstruction for Ammonia Synthesis

High-entropy electrocatalysts have garnered an increasing attention in electrocatalytic applications due to their outstanding redox reaction capabilities, as well as their selective and stable properties. The deliberate design of high-entropy materials with high metallic vacancy concentrations and intrinsic strain features with an induced localized empty electronic state and charge redistribution at the bandgap level. A Al/Zn-etched high-entropy FeCoNiAlZnCu layered double hydroxide achieves a maximum ammonia Faradaic efficiency of 98.57% at -0.5 V with a production rate of 40.34 mg h-1 cm-2 for the nitrate reduction reaction. Furthermore, it exhibits a favorable oxygen evolution activity with an overpotential of 300 mV at 10 mA cm-2 and a Tafel slope of 92.5 mV dec-1. Combined with advanced spectroscopic techniques, it reveals that the local metallic vacancy defects can modulate catalytic active sites by stimulating electron accumulation and creating unsaturated coordination around the electrocatalytic sites. The synergistic interaction between the internal strain and electronic rearrangement can enhance intrinsic catalytic active sites, thus reducing absorbed energy barrier, boosting electron transfer kinetics, and stabilized intrinsic catalytic structure.