An Overview of Recent Advances in the Synthesis and Applications of the Transition Metal Carbide Nanomaterials

Abstract

Good stability and reproducibility are important factors in determining the place of any material in their respective field and these two factors also enable them to use in various applications. At present, transition metal carbides (TMCs) have high demand either in the two-dimensional (2D) form (MXene) or as nanocomposites, nanoparticles, carbide films, carbide nano-powder, and carbide nanofibers. They have shown good stability at high temperatures in different environments and also have the ability to show adequate reproducibility. Metal carbides have shown a broad spectrum of properties enabling them to engage the modern approach of multifacet material. Several ways have been routed to synthesize metal carbides in their various forms but few of those gain more attention due to their easy approach and better properties. TMCs find applications in various fields, such as catalysts, absorbents, bio-sensors, pesticides, electrogenerated chemiluminescence (ECL), anti-pollution and anti-bacterial agents, and in tumor detection. This article highlights some recent developments in the synthesis methods and applications of TMCs in various fields.

Mo2C as Pre-Catalyst for the C-H Allylic Oxygenation of Alkenes and Terpenoids in the Presence of H2O2

“…The results are summarized in Table 1 (entries 9 and 10). In both cases, similar product yields were observed by 1 H NMR of the crude reaction mixtures. These results indicated that the observed polyoxometalate was a plausible active catalytic species for the present oxygenation of 1.…”

“…are required to achieve higher than 95% conversion of 1, whilst the product yields and the reaction profile were found not to be affected by higher amount of H 2 O 2 or prolonged reaction time (24 h) (Table S3). Temperature-dependent experiments showed that 25 • C is the appropriate temperature for the fast consumption of 1 within 3 h, while by increasing to 60 • C, the corresponding allylic hydroperoxides 1a' and 1b' were formed with similar relative yields as determined by 1 H NMR and GC after reduction with the addition of excess of PPh 3 (Table S4).…”

“…5:1 ratio), respectively. The corresponding [4 + 2] cycloadduct 1c' was formed in 9% yield (Table 1, entry 2), as determined by 1 H NMR spectroscopy [66]. By increasing the reaction time to 3 h, an almost quantitative consumption of 1 was observed with the allylic hydroperoxides 1a' and 1b', forming in 61% and 12% yields, respectively (Table 1, entries 3 and 4).…”

“…Meanwhile, under prolonged reactions times (up to 8 h), no significant changes were observed in the product yields (results not shown). Moreover, when the addition of H 2 O 2 was made via a syringe pump apparatus (see SI) within 3 h with a constant flow rate at 100 µL/h, and allowing the process to continue for an additional 3 h, no changes on the product yields were observed by 1 H NMR spectroscopy (Table 1, entry 5). It is interesting to note that by using lower catalyst loading, no reaction completion was observed, while higher catalyst loadings did not significantly alter the reaction conversion and product yields (Table 1, entries 6-8).…”

“…In recent years, the use of low cost, renewable and bio-based materials as catalysts has received increasing attention in the field of green and sustainable chemistry. Among the widely used, early-transition-metal catalytic materials, the carbides of the earth-abundant Mo and W (Mo 2 C and W 2 C) [1][2][3] feature catalytic properties similar to those of noble metals [4,5]. Several catalytic processes, including Fischer-Tropsch (FT) synthesis [6,7], methane dry reforming [8], water-gas shift (WGS) reaction [9,10], alkenes [11] and CO/CO 2 hydrogenation into value-added chemicals (methanol, dimethyl ether) or fuels (methane and heavier hydrocarbons), have been reported using these two materials [12][13][14][15][16][17][18].…”