An Easy Catalyst-Free Hydrothermal Method to Prepare Monodisperse Carbon Microspheres on a Large Scale

Abstract

We report an easy catalyst-free method to prepare carbon microspheres via a hydrothermal carbonization process using starch solution as starting materials. SEM and TEM images show that the products consist of a large scale of monodisperse carbon microspheres with a size of about 2 µm. The size of the carbon microspheres can be easily controlled by regulating the concentration of the starch solution and the reaction temperature. Furthermore, the surface of the spheres is functionalized with hydroxyl and carboxyl groups, which make further surface modification unnecessary and facilitate immobilization of noble metal nanoparticles and fabrication of core-shell materials or hollow structures. Through SEM observation, the mechanism of the formation of carbon microspheres under hydrothermal conditions was suggested to be a direct dehydration polymerization and self-assemble fusion process. The present work provides a convenient yet effective method for large-scale synthesis of monodisperse carbon microspheres with high purity.

Diamond-Like Carbon Nanofoam from Low-Temperature Hydrothermal Carbonization of a Sucrose/Naphthalene Precursor Solution

“…For example, the hydrothermal carbonization was performed for cellulose in the 220-250 °C range [40], for glucose between 170 and 500 °C [19,[41][42][43][44], for sucrose at 190 °C [45] and for starch at 600 °C [46]. Process times were typically between 4 and 12 h. For some of the materials, the graphitic nature has been improved by annealing the sample after synthesis.…”

A Review of Hydrothermal Carbonization of Carbohydrates for Carbon Spheres Preparation

“…HTC had a wide range of possible sources such as carbohydrates (glucose, fructose, xylose, sucrose, cellulose, and starch) [31,34], biomass [35], sewage sludge, animal manure, municipal solid waste [44], agricultural residues, and algae [24]. It's difficult for HTC of biomass to form carbon spheres with regular morphology in a uniform chemical structure compared to simple saccharides.…”

Hybrid metal oxide@biopolymer materials precursors of metal oxides and metal oxide-carbon composites

“…It was soon tested as a "structure directing agent" or a "porogen" or an alternative of citric acids being easily removed with water. 16) Starch was also used as hard-templating microspheres infiltrated with metal oxide sol, 107) or were first converted to carbonaceous material by a solvothermal process, 108) and then used as sacrificial templates for the preparation of ZnO microspheres after impregnation with Zin(II) acetate. 109),110) Among the possible oxides (Table 4) several recent works focus on the Journal of the Ceramic Society of Japan 123 [9] 695-708 2015 JCS-Japan Cotton and paper fibers ZnO Material for electrochemical devices.…”