Synthesis and Characterization of CdS/TiO2-Montmorillonite Nanocomposite with Enhanced Visible-Light Absorption

Sodium montmorillonite (MMT) was chosen as the carrier; a serial of CdS/TiO2-MMT nanocomposites with enhanced visible-light absorption ability was prepared by hydrothermal synthesis method combination with semiconductor compound modification method. The samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy; the results showed that TiO2 and CdS nanoparticles were loaded on the surface of montmorillonite uniformly. N2 adsorption-desorption experiment showed that the specific surface area of TiO2/montmorillonite nanocomposite made by this method can reach 200？m2/g and pore-size distribution was from 4 to 6？nm; UV-Vis showed that the recombination of CdS and TiO2 enhanced visible-light absorption ability of samples of TiO2/montmorillonite and visible-light absorption ability increase with the increased of the adsorption of CdS. 1. Introduction The bentonite is a kind of clay mineral mainly consisting of montmorillonite (MMT); the crystal structure of MMT is 2？:？1 layered silicates [1]. Pillared clay is a new mineral that used the high temperature resistant pillared agent with positively charged replaced the exchangeable positive ions in the montmorillonite, bridging the crystal structure of 2？:？1 layered silicates and put them open, and formed a kind of “layered and columnar” structure of two-dimensional passage [2]. Ti-pillared clay (Ti-PILC) has pore structure, large specific surface area, and thermal stability. Therefore, they are being used in many applications such as the preparation of catalyst, catalyst carrier, molecular sieve, adsorbent, environmental protection material, ion exchanger, conductive material, storage material, and nanocomposites [3–5]. At present, the preparation methods of TiO2 pillared clay are Ti inorganic salt hydrolysis [6] or Sol-Gel method of Ti alkoxides [1]. But the particle size of hydrated titanium ion gel particles mn+ is only 1-2？nm, which is precursor of titanium oxide particles by the traditional method. The photocatalytic efficiency is relatively low; most of interlayer pores are micropores that hinder the contact between the substrate and catalyst for undersized titanium oxide between Montmorillonite interlayer. Next, the band gap of TiO2 is wider (Eg = 3.2？eV) and the efficiency of water used is low for it only can be excited at near ultraviolet, in which the wavelength is equal to or less than 387？nm in the sunlight. The structure of Ti-pillared montmorillonite, which is prepared by hydrothermal synthesis method, is exfoliated.