Preparation method for nanosheet of uniformly dispersed layered double hydroxides (LDHs)

Abstract

The invention belongs to the technical field of nanometer material preparation and relates to a preparation method for a nanosheet of uniformly dispersed layered double hydroxides (LDHs). The preparation method comprises the steps as follows: firstly, mixing a soluble bivalent inorganic salt M<2+>Y with a soluble trivalent inorganic salt M<3+>Y and dissolving in de-ionized water to prepare a salt solution; secondly, preparing an alkali solution by adopting the conventional technology; thirdly, fully mixing and reacting the salt solution with the alkali solution by utilizing a micro-channel reactor to obtain deposits of LDHs; and lastly, fully washing the deposits with the de-ionized water and centrifuging to obtain jelly with a single-layer nanosheet, which is the nanosheet of uniformly dispersed LDHs. The nanosheet of uniformly dispersed LDHs is simple to prepare, moderate in preparation conditions, low in cost, environment-friendly in production, wide in application range, and high in economic value.

Description

Technical field: [0001] The invention belongs to the technical field of nanomaterial preparation, and relates to a preparation process of nanomaterials, in particular to a preparation method of homogeneously dispersed hydrotalcite-like nanometer sheets. Background technique: [0002] Layered Double Hydroxides (LDHs for short), also known as hydrotalcite-like, is a typical anionic layered material, and its chemical composition formula is [M 2+ 1-x m 3+ x (OH) 2 ] x+ (A n- ) x / n ·yH 2 O, where M 2+ Represents the divalent metal ion Mg 2+ 、Co 2+ 、Ni 2+ , Fe 2+ , Mn 2+ , Zn 2+ any of the 3+ for Al 3+ or Fe 3+ ;A n- for NO 3 - , F - 、Br - , Cl - , CO 3 2- SO 4 2- Any one of them; 0.17≤x≤0.35; m is the amount of crystal water, the element type and composition ratio of the main layer of LDHs, and the type and quantity of interlayer objects can be adjusted in a wide range according to the needs, so as to obtain Materials with special structures and proper...

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Problems solved by technology

At present, there are two main methods for preparing hydrotalcite-like nanosheets with a single-layer or few-layer structure: "top-down method" and "bottom-up method"; "top-down method" is to prepare hydrotalcite-like nanosheets first. The crystal is then peeled off its sheet. This method is mainly carried out in organic solvents, such as: n-butanol, acrylic acid, formamide, etc., literature (Gardner, E.; Huntoon, K.M.; Pinnavaia, T.J.Direct synthesis of alkoxide -intercalated derivatives of hydrocalcite-like Layered double hydroxides: Precursors for the formation of colloidal layered double hydroxide suspensions and transparent thin films. Adv. Mater. 2001, 13, 1263) discloses a hydrotalcite-like exfoliation in aqueous solution The method of inserting the alkoxide into the hydrotalcite-like layer to form a hybrid, and then peeling off the layer in water, the surface of the hydrotalcite-like nanosheet obtained by this method is adsorbed with organic molecules, which is not conducive to the further assembly process. The "bottom-up method" is a method for directly preparing hydrotalcite-like monoliths, and there are few reports so far. Literature (Hu, G.; Wang, N.; O'Hare, D.; Davis, J. One-step synthesis and AFM imaging of hydrophobic LDH monolayers, Chem.Commun.2006, 287) discloses that a hydrotalcite-like structure with a single-layer structure can be prepared in an inverse microemulsion, but its surface still adsorbs organic molecules; co-precipitation The method is the most commonly used method for preparing LDHs. The microreactor can prepare homogeneously dispersed nanoparticles because it can make the liquid mix well and separate the crystal growth from aging. Literature (Y.Ying, G.W.Chen, Y.C.Zhao, S.L.Li, Q.Yuan, A high throughput methodology for continuous preparation of monodispersed nanocrystals in microfluidic reactors Chem.Eng.J., 2008,135,209.) discloses the use of T-shaped microreactors to prepare homogeneously dispersed nano-BaSO 4 Particles; literature (Y.Zhao, F.Li, Y.Zhao, F.Li, R.Zhang, D.G.Evans, X.Duan, Preparation of layered double-hydroxide nanomaterials with a uniform crystallitesize using a new method involving separate nucleation and aging steps, Chem.Mater., 2002, 14:4286.) discloses the use of a colloid mill to prepare hydrotalcite-like particles with uniform particle size by co-precipitation method, but so far, there has been no use of co-precipitation method to prepare uniformly dispersed hydrotalcites. A report on monolayer nanosheets of hydrotalcite

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