Quasi-continuous synthesis of LDHs with controllable element ratio, uniform element distribution, and rich oxygen vacancy via a chaotic microreactor

Abstract

A chaotic oscillating feedback microreactor (OFM) was designed to prepare LDHs for oxygen evolution reaction (OER). Firstly, the chaotic mixing mechanism, chaos intensity characterization, and chaotic mixing performance were investigated by both the experimental and computational fluid dynamics simulations. It indicated that uniform concentration field was induced owing to the efficient chaotic mixing. Secondly, the LDH (i.e., F-LDH) was prepared by OFM, and relative characterization results indicated that the OFM method could overcome the limitation of thermodynamic solubility equilibrium constants of different metals by fast synthesis kinetics. The F-LDH presented more controllable metal element ratios, uniform elements distribution and abundant oxygen defects than those using the batch method. The electrochemical test results described that F-LDH exhibited an efficient electrocatalytic activity with an overpotential of 370 mV at a current density of 100 mA cm⁻² and a Tafel slope of 71 mV dec^-1 for the basic OER.