Qiuling Chen

Monoclinic C2/m-20 carbon: a novel superhard sp3 carbon allotrope

Based on density function theory with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation, the structural, mechanical, and electronic properties of C2/m-20 carbon have been systematically investigated in this paper. The elastic constants and phonon spectra calculations show that C2/m-20 carbon is mechanically stable and dynamically stable at 0 GPa and 100 GPa. From our calculations, we found that C2/m-20 carbon has a larger bulk modulus of 412 GPa, a larger shear modulus of 463 GPa, a larger Young’s modulus of 1010 GPa, and a hardness of 70.6 GPa, which means that it is a superhard material with potential technological and industrial applications. C2/m-20 carbon exhibits greater anisotropy than C2/m-16 carbon and M-carbon using Young’s modulus and the universal anisotropic index. In addition, C2/m-20 carbon is an indirect and wide semiconductor with a band gap of 5.10 eV. The most extraordinary thing is that the band gap increases with increasing pressure.

Catalytic gasification of phenol in supercritical water with Ru/graphitized carbon black

Phenol is a long-lived intermediate, and it is ubiquitous in the supercritical water gasification (SCWG) processes of various organic materials such as biomass, lignite and sewage sludge. In this work, ruthenium supported on graphitic carbon black (Ru/GCB) was prepared for catalytic gasification of phenol in supercritical water. It exhibited excellent catalytic performance towards phenol gasification, a nearly complete gasification of phenol was achieved at a moderate temperature of 500 °C with an 1 g g−1 catalyst loading. Kinetic study indicated the activation energy and the frequency factor for phenol gasification were 154.0 ± 27.2 kJ mol−1 and 23.2 ± 4.5, respectively. Furthermore, catalyst recycling experiments were conducted to evaluate the stability of Ru/GCB catalyst in the SCWG. X-ray diffraction, Raman spectrum, N2 adsorption, X-ray photoelectron spectroscopy and transmission electron microscopy were performed to characterize the fresh and used catalyst in order to investigate possible changes of catalyst after the recycling, the results indicated that the catalyst was found to be stable for phenol gasification under the experimental conditions.