A general strategy for the synthesis of layered double hydroxide nanoscrolls on arbitrary substrates: its formation and multifunction

Synthesis of structure-controlled nanocrystals on target substrates presents an enticing prospect for fabricating multifunctional devices. Herein, layered double hydroxides (LDHs) with different morphologies were fabricated via hydrothermal treatment on various substrate surfaces. The morphology of the LDH nanostructures from ultrathin nanosheets, parallel aligned nanoscrolls and vertically aligned nanoscrolls could be finely tuned by adjusting the reaction time, temperature and metal-salt concentration. A speculative model was proposed to illustrate the reaction process where the LDH growth units interacted with the modified surface at first, then gradually formed the nanosheets and finally developed into nanoscrolls upon termination of the reaction. The investigation confirmed that amino groups and a positively charged surface play key roles in the formation of well-defined LDH nanoscrolls. Benefiting from the unique hierarchical structure and high LDH loading, the hybrid nanofiber membranes with vertically aligned LDH nanoscrolls exhibited excellent adsorption capability toward methyl orange and Cu2+ and could effectively separate a surfactant stabilized oil-in-water emulsion solely by gravity, with high flux and oil rejection. Meanwhile, these hybrid membranes have shown great potential as highly efficient catalysts for degradation of organic pollutants, making them versatile and comprehensive materials for water remediation.