Synthesis of Monolithic TiO2 Aerogels With Relatively Low Shrinkage and Improved Formability Assisted by CTAB

Tingting Niu,Zhihua Zhang,Jianming Yang,Zehui Zhang,Bin Zhou,Xiujie Ji,Jun Shen,Ai Du

doi:10.3389/fmats.2021.674578

Abstract

Monolithic TiO2 aerogels without severe shrink were obtained by the sol-gel method with the addition of the surfactant cetyltrimethylammonium bromide (CTAB) to control the hydrolysis and polycondensation process and acetonitrile solvent as the solvent to improve the crystallinity. After CO2 supercritical drying, the shrinkage ratio of monolithic TiO2 aerogels modified by CTAB decreased by up to ∼26.9%, compared with the pure TiO2 aerogel. Their apparent densities were all lower than 300 g/cm3. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR) and BET Specific Surface Area Analysis were used to analyze the as-synthesized samples. The results revealed that all the samples were anatase-TiO2 phase with nanoporous network structures. The specific surface areas reached 250.2 m2/g confirmed by the BET (Brunaur–Emmett–Teller method) analysis. However, TiO2 aerogels without the addition of CTAB showed evident agglomeration and collapse of the network in comparison with CTAB-added samples. To further study the structure-property relationship, the photocatalysis performance of as-synthesized and 300°C-calcined aerogels was carried out contrastively. Interestingly, the influences of the CTAB adding amount of as-synthesized and calcined TiO2 aerogels are negative and positive, respectively, which is probably due to the synergistic effect of CTAB hindrance and grain refinement. Potentially, This kind of TiO2 aerogels assisted by CATB with low density, small shrinkage, improved formability, high specific surface area and fine crystalline grain may be applied in various applications, such as electrochemistry, photocatalysis, etc.

Highlights

Nano-TiO2 materials have become a widely concerned research topic worldwide due to their excellent semiconductor properties (Chen, 2009; Muniz et al, 2011; Noman et al, 2019; Xie et al, 2019)
It indicated that the shrinkage ratio of monolithic TiO2 aerogels modified by cetyltrimethylammonium bromide (CTAB) decreased by up to ∼26.9%, compared with pure TiO2 aerogels (CTAB-0)
Five TiO2 aerogels were compared to study the effect of the CTAB adding amounts

Summary

Introduction

Nano-TiO2 materials have become a widely concerned research topic worldwide due to their excellent semiconductor properties (Chen, 2009; Muniz et al, 2011; Noman et al, 2019; Xie et al, 2019). Photocatalysis is one of the most popular topics (Znaidi et al, 2001; Topcu et al, 2016; Guo et al, 2018; Sanjay et al, 2019), and its efficiency is primarily affected by the specific surface area and grain size. As aerogel is a kind of material with high specific surface area and large porosity(Wen et al, 2018; Yan et al, 2018; Bi et al, 2019; Wen et al, 2020), it is a better choice. It is tough to prepare a kind of TiO2 aerogel with low density and high porosity. It is widely believed that molding the TiO2 aerogel, fragile and easy to shrink, is really challenging

Methods

Results

Conclusion