An aerogel adsorbent with bio-inspired interfacial adhesion between graphene and MoS2 sheets for water treatment

The increasing environmental pollution calls for the development of stable functional materials for efficiently binding contaminants, while they can be synthesized and recycled easily. Herein, a three-dimensional (3D) aerogel is constructed by bio-inspired adhesion of graphene and MoS2 sheets with polydopamine (PDA) through a one-step hydrothermal route for the adsorption of the water-soluble organic contaminants. The impact of the bio-inspired interfacial adhesion on the resulting composite aerogel is thoroughly investigated, e.g., the interfacial PDA layer renders the composite aerogel considerably more porous, together with the much higher specific surface area and pore volume, as well as strikingly smaller average pore size and superior stability upon exposure to air, relative to the counterpart without the bio-inspired adhesion. The 3.2 wt% PDA composition is adequate to yield a composite structure with small MoS2 nanocrystallites uniformly dispersed over the modified graphene surface without aggregation. The adsorption of methylene green onto such a 3D composite architecture is spontaneous and endothermic and obeys the Langmuir isotherm model and pseudo-second-order kinetics, with the maximum adsorption capacities over 200 mg/g at all the operating temperatures and the satisfactory recycling properties without significant degradation after 5 cycles.