In-situ construction of lamellar stacked zinc molybdate-zinc/aluminium layered double hydroxides heterojunction material with synergistic corrosion protection

The design of heterojunction materials is a practical but challenging subject in the corrosion protection field. With the in-situ growth strategy, the zinc-aluminium layered double hydroxides (LDH) nanoflakes were bound tightly on the surface of zinc molybdate (ZMO). The mechanism of corrosion protection was researched systematically. The electron-hole pair separation efficiency enhanced by forming the Z-scheme heterojunction structure provided photoinduced electron protection and retarded corrosion process. Benefit from the stacked lamellar and the hydrogen bond effect, which improved the compactness and compatibility of coating, the multi-level shielding effect prevented the permeation of corrosive media. Moreover, the anion traps consisted of the interlayer corridor structure in the LDH and the corrosion inhibition ability of molybdate synergistically granted the composite epoxy coating with better protection performance. Furthermore, the addition of ZMO-LDH could also enhance the mechanical strength and the elasticity modulus of epoxy samples, which reached to 130.7 % and 148.6 % of the neat epoxy resin . The electrochemical test results exhibited that the total impedance value of ZMO-LDH composite coating respectively increased by 322.9 %, 184.7 % and 117.6 % respectively compared with the epoxy resin coating, zinc molybdate coating and zinc-aluminium layered double hydroxides coating, showing heterojunction material had the best electrochemical corrosion protection performance. Herein, constituting heterojunction materials with suitable energy band and compact structure can effectively improve electrochemical corrosion protection and physical durability, which has reference values for designing anticorrosion heterojunction materials.