Generation and Characteristics of IV-VI transition Metal Nitride and Carbide Nanoparticles using a Reactive Mesoporous Carbon Nitride

Abstract

Abstract:Interstitial nitrides and carbides of early transition metals in groups IV-VI exhibit platinum-like electronic structures, which make them promising candidates to replace noble metals in various catalytic reactions. Herein, we present the preparation and characterization of nano-sized transition metal nitries and carbides of groups IV-VI (Ti, V, Nb, Ta, Cr, Mo, and W) using mesoporous graphitic carbon nitride (mpg-C3N4), which not only provides confined spaces for restricting primary particle size but also acts as a chemical source of nitrogen and carbon. We studied the reactivity of the metals with the template under N2 flow at 1023 K while keeping the weight ratio of metal to template constant at unity. The produced nanoparticles were characterized by powder X-ray diffraction, CHN elemental analysis, nitrogen sorption, X-ray photoelectron spectroscopy, and transmission electron microscopy.The results show that Ti, V, Nb, Ta, and Cr form nitride phases with face centered cubic structure, whereas Mo and W forme carbides with hexagonal structures. The tendency to form nitride or carbide obeys the free formation energy of the transition metal nitrides and carbides.This method offers the potential to prepare the desired size, shape and phase of transition 2 metal nitrides and carbides that are suitable for a specific reaction, which is the chief objective of materials chemistry.

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

“…205,206 The β-W 2 C phase is only reported at >20 nm particle sizes and only from a single reference. 207 To the best of our knowledge, ε-W 2 C nanoparticles are reported only in the intermediate range of 6−9 nm, 208,209 consistent with Figure 10a. We were unable to find any reports for γ-W 2 C particle sizes.…”

“…When tungsten oxide is used as a precursor for synthesis, oxycarbides are formed at temperatures <900 K, and the temperature is increased to obtain tungsten carbide phases. , The β-W 2 C phase is only reported at >20 nm particle sizes and only from a single reference . To the best of our knowledge, ε-W 2 C nanoparticles are reported only in the intermediate range of 6–9 nm, , consistent with Figure a. We were unable to find any reports for γ-W 2 C particle sizes.…”

Synthesis of niobium(iv) carbide nanoparticles via an alkali-molten-method at a spatially-limited surface of mesoporous carbon

“… 21 Takanabe and his co-workers succeeded in the synthesis of various TMCs including NbC nanoparticles with the size of <10 nm by a skillful strategy using ethanol solution of metal precursors and mesoporous graphitic carbon nitride (mpg-C 3 N 4 ), in which the TMC nanoparticles were produced in the mesopores of mpg-C 3 N 4 . 22 As we can see in the pioneered study such as aforementioned literature, the key point on the preparation of size-controlled TMC nanoparticles is “reaction field”. In other words, the size-controlled TMC nanoparticles are afforded resulting from precise design of the reaction field of a carbonization of metal species precursor.…”

“…Regarding this, the preparation of nano-sized NbC has been addressed by a lot of researchers to increase active sites per weight on the catalysis. 6,[21][22][23][24][25][26][27][28][29][30][31][32] Recently, Tour and Zhao et al synthesized NbC nanoparticles with ca. 20 nm of size via novel ash Joule heating in the reactor composed of capacitor banks, electrodes, quartz and a carbon source.…”