Voronoi‐Tessellated Graphite Produced by Low‐Temperature Catalytic Graphitization from Renewable Resources

Abstract

A highly crystalline graphite powder was prepared from the low temperature (800-1000 °C) graphitization of renewable hard carbon precursors using a magnesium catalyst. The resulting graphite particles are composed of Voronoi-tessellated regions comprising irregular sheets; each Voronoi-tessellated region having a small "seed" particle located near their centroid on the surface. This suggests nucleated outward growth of graphitic carbon, which has not been previously observed. Each seed particle consists of a spheroidal graphite shell on the inside of which hexagonal graphite platelets are perpendicularly affixed. This results in a unique high surface area graphite with a high degree of graphitization that is made with renewable feedstocks at temperatures far below that conventionally used for artificial graphites.

Construction of a Nanoporous Highly Crystalline Hexagonal Boron Nitride from an Amorphous Precursor for Catalytic Dehydrogenation

“…Under otherwise identical treatment conditions,t he h-BN samples obtained at calcination temperatures of 800 8 8Ca nd 1000 8 8Cl ed to amorphous materials,a ss hown by the PXRD patterns ( Figure 3B). [26,30] Considering the high thermal stability of h-BN (up to 2800 8 8C) under N 2 , [31] the recrystallization process of h-BN in this work was estimated to proceed through adissolution-precipitation mechanism. TheP XRD results also showed that as hort reaction time (20 min) or low heating temperature led to asmall amount of carton nitride (JCPDS card no.5 0-0664) formation within the obtained h-BN samples.A sp reviously reported, dissolution-precipitation mechanism and formation-decomposition of carbide intermediate mechanism have been proposed to explain the graphitization process in the presence of metal catalysts.…”

“…TheP XRD results also showed that as hort reaction time (20 min) or low heating temperature led to asmall amount of carton nitride (JCPDS card no.5 0-0664) formation within the obtained h-BN samples.A sp reviously reported, dissolution-precipitation mechanism and formation-decomposition of carbide intermediate mechanism have been proposed to explain the graphitization process in the presence of metal catalysts. [26,30] Considering the high thermal stability of h-BN (up to 2800 8 8C) under N 2 , [31] the recrystallization process of h-BN in this work was estimated to proceed through adissolution-precipitation mechanism.…”

“…[23,24] Our group has reported asimple electrochemical route for the graphitization of amorphous carbons through cathodic polarization in molten CaCl 2 ,a nd the resultant nanostructured graphite exhibited good performance as as uperior cathode material for batteries. [26] Ther ecrystallization process is illustrated in Figure 1A.The h-BN precursor was first mixed with Mg powder, and then the mixture was sealed in stainless-steel tubes and treated at 900 8 8Cunder N 2 atmosphere (for details, see Supporting Information). [26] Ther ecrystallization process is illustrated in Figure 1A.The h-BN precursor was first mixed with Mg powder, and then the mixture was sealed in stainless-steel tubes and treated at 900 8 8Cunder N 2 atmosphere (for details, see Supporting Information).…”

“…[25] Herein ac rystallization strategy was adopted for the transformation of h-BN material in the presence of molten metals.M agnesium was selected as the reagent used to treat the amorphous h-BN precursor,c onsidering its appropriate melting point (650 8 8C) and good performance in the fabrication of crystalline graphite powder from renewable hard carbon precursors. [26] Ther ecrystallization process is illustrated in Figure 1A.The h-BN precursor was first mixed with Mg powder, and then the mixture was sealed in stainless-steel tubes and treated at 900 8 8Cunder N 2 atmosphere (for details, see Supporting Information). After removing the Mg by washing, crystalline h-BN was obtained with ay ield of 88 % by weight.…”

Construction of a Nanoporous Highly Crystalline Hexagonal Boron Nitride from an Amorphous Precursor for Catalytic Dehydrogenation

“…Herein a crystallization strategy was adopted for the transformation of h‐BN material in the presence of molten metals. Magnesium was selected as the reagent used to treat the amorphous h‐BN precursor, considering its appropriate melting point (650 °C) and good performance in the fabrication of crystalline graphite powder from renewable hard carbon precursors . The recrystallization process is illustrated in Figure A.…”