Predicting Points of Zero Net Charge of Layered Double Hydroxides

Many models such as electrostatic and crystallographic models have been developed to predict the point of zero net charge (PZNC) of (hydr)oxides without structural charges. Nevertheless, there is still a lack of feasible models for the prediction of the PZNC of structurally charged (hydr)oxides such as layered double hydroxides (LDHs), a large class of lamellar inorganic materials possessing positive structural charges. Herein, a modified electrostatic model is proposed by taking the structural charge (σ_st) and the Pauling's electrostatic valence principle into account, to correlate the PZNC with the characteristic physical constants of (hydr)oxides. The new model suggests that the PZNC of structurally charged (hydr)oxides is proportional to their σ_st, which was confirmed by the PZNC data of 28 LDH samples. The model can be used to describe or predict the PZNC of LDHs and also may provide guidance for the designed synthesis and application of LDH materials.