Revealing the Formation Mechanism and Optimizing the Synthesis Conditions of Layered Double Hydroxides for the Oxygen...

Layered double hydroxides (LDHs), whose formation is strongly related to OH^- concentration, have attracted significant interest in various fields. However, the effect of the real-time change of OH^- concentration on LDHs' formation has not been fully explored due to the unsuitability of the existing synthesis methods for in situ characterization. Here, the deliberately designed combination of NH₃ gas diffusion and in situ pH measurement provides a solution to the above problem. The obtained results revealed the formation mechanism and also guided us to synthesize a library of LDHs with the desired attributes in water at room temperature without using any additives. After evaluating their oxygen evolution reaction performance, we found that FeNi-LDH with a Fe/Ni ratio of 25/75 exhibits one of the best performances so far reported.