Enhanced the Overall Water Splitting Performance of Quaternary NiFeCrCo LDH: Via Increasing Entropy.

The construction of high-performance catalysts for overall water splitting (OWS) is crucial. Nickel-iron-layered double hydroxide (NiFe LDH) is a promising catalyst for OWS. However, the slow kinetics of the HER under alkaline conditions seriously hinder the application of NiFe LDH in OWS. This work presents a strategy to optimize OWS performance by adjusting the entropy of multi-metallic LDH. Quaternary NiFeCrCo LDH was constructed, which exhibited remarkable OWS activity. The OER and HER of NiFeCrCo LDH were stable for 100 h and 80 h, respectively. The OWS activity of NiFeCrCo LDH//NiFeCrCo LDH only required 1.42 V to reach 10 mA cm, and 100 mA cm required 1.54 V. Under simulated seawater conditions, NiFeCrCo LDH//NiFeCrCo LDH required 1.57 V to reach 10 mA cm and 1.71 V to reach 100 mA cm. The introduction of Co into the structure induced Cr to provide more electrons to Fe, which regulated the electronic state of NiFeCrCo LDH. The appropriate electronic state of the structure is essential for the remarkable performance of OWS. This work proposes a new strategy to achieve excellent OWS performance through entropy-increase engineering.