Silicon Oxycarbide-Derived Hierarchical Porous Carbon Materials for Rhodamine B and CO2 Adsorption

The hollow mesoporous silicon oxycarbide (SiOC) ceramics without mixed Si−O−C units (SiO2/C composites) were synthesized through the solvothermal route in Na2CO3 solution, and porous carbon materials were prepared by HF etching. Amorphous SiO2 is transformed into cristobalite SiO2 as the increase in pyrolysis temperature from 1000 to 1400 °C, while the free C (Cfree) content decreases as the elevation of pyrolysis temperature. The carbothermal reduction reaction of SiO2 with Cfree not only results in the formation of SiC nanowires, but also further reduces the C content. However, after HF etching, the C content in carbon materials increases as elevation of pyrolysis temperature, and more micro-/mesopores are created by removal of SiO2. The microstructure and porosity of carbon materials are tailorable by simple changing the pyrolysis temperature. Furthermore, the HF etching results in the insertion of F only in SiO2 and which has no effect on the Cfree. The hierarchical porous structure in conjunction with surface oxygen-containing functional group make the carbon materials obtained at 1400 °C exhibit the good rhodamine B (RhB) and CO2 adsorption performance. The maximum RhB and CO2 adsorption capacity is 130.9 mgg−1 and 1.31 mmolg−1, respectively.