Properties of nanosheets of 2D-borocarbonitrides related to energy devices, transistors and other areas

Borocarbonitride-Based Emerging Materials for Supercapacitor Applications: Recent Advances, Challenges, and Future Perspectives

Supercapacitors have emerged as a promising energy storage technology due to their high-power density, fast charging/discharging capabilities, and long cycle life. Moreover, innovative electrode materials are extensively explored to enhance the performance, mainly the energy density of supercapacitors. Among the two-dimensional (2D) supercapacitor electrodes, borocarbonitride (BCN) has sparked widespread curiosity owing to its exceptional tunable properties concerning the change in concentration of the constituent elements, along with an excellent alternative to graphene-based electrodes. BCN, an advanced nanomaterial, possesses excellent electrical conductivity, chemical stability, and a large specific surface area. These factors contribute to supercapacitors' overall performance and reliability, making them a viable option to address the energy crisis. This review provides a detailed survey of BCN, its structural, electronic, chemical, magnetic, and mechanical properties, advanced synthesis methods, factors affecting the charge storage mechanism, and recent advances in BCN-based supercapacitor electrodes. The review embarks on the scrupulous elaboration of ways to enhance the electrochemical properties of BCN through various innovative strategies followed by critical challenges and future perspectives. BCN, as an eminent electrode material, holds great potential to revolutionize the energy landscape and support the growing energy demands of the future.

Theoretical prediction of two-dimensional BC2X (X = N, P, As) monolayers: ab initio investigations

In this work, novel two-dimensional BC[Formula: see text]X (X = N, P, As) monolayers with X atoms out of the B-C plane, are predicted by means of the density functional theory. The structural, electronic, optical, photocatalytic and thermoelectric properties of the BC[Formula: see text]X monolayers have been investigated. Stability evaluation of the BC[Formula: see text]X single-layers is carried out by phonon dispersion, ab-initio molecular dynamics (AIMD) simulation, elastic stability, and cohesive energies study. The mechanical properties reveal all monolayers considered are stable and have brittle nature. The band structure calculations using the HSE06 functional reveal that the BC[Formula: see text]N, BC[Formula: see text]P and BC[Formula: see text]As are semiconducting monolayers with indirect bandgaps of 2.68 eV, 1.77 eV and 1.21 eV, respectively. The absorption spectra demonstrate large absorption coefficients of the BC[Formula: see text]X monolayers in the ultraviolet range of electromagnetic spectrum. Furthermore, we disclose the BC[Formula: see text]N and BC[Formula: see text]P monolayers are potentially good candidates for photocatalytic water splitting. The electrical conductivity of BC[Formula: see text]X is very small and slightly increases by raising the temperature. Electron doping may yield greater electric productivity of the studied monolayers than hole doping, as indicated by the larger power factor in the n-doped region compared to the p-type region. These results suggest that BC[Formula: see text]X (X = N, P, As) monolayers represent a new promising class of 2DMs for electronic, optical and energy conversion systems.

Low-Temperature Direct Growth of Few-Layer Hexagonal Boron Nitride on Catalyst-Free Sapphire Substrates

Wide-band-gap layered semiconductor hexagonal boron nitride (h-BN) is attracting intense interest due to its unique optoelectronic properties and versatile applications in deep ultraviolet optoelectronic and two-dimensional electronic devices. However, it is still a great challenge to directly grow high-quality h-BN on dielectric substrates, and an extremely high substrate temperature or annealing is usually required. In this work, high-quality few-layer h-BN is directly grown on sapphire substrates via ion beam sputtering deposition at a relatively low temperature of 700 °C by introducing NH₃ into the growth chamber. Such low growth temperature is attributed to the presence of abundant active N species, originating from the decomposition of NH₃ under ion beam irradiation. To further tailor the properties of h-BN, carbon was introduced into the h-BN layer by simultaneously introducing CH₄ and NH₃ during the growth process, indicating the wide applicability of this approach. Moreover, a deep ultraviolet (DUV) photodetector is also fabricated from a C-doped h-BN layer and exhibits superior performance compared with an intrinsic h-BN device.

Deep Ultraviolet Photodetectors Based on Carbon-Doped Two-Dimensional Hexagonal Boron Nitride

Recently, the deep ultraviolet (DUV) photodetectors fabricated from two-dimensional (2D) hexagonal boron nitride (h-BN) layers have emerged as a hot research topic. However, the existing studies show that the h-BN-based photodetectors have relatively poor performance. In this work, C doping is utilized to modulate the properties of h-BN and improve the performance of the h-BN-based photodetectors. We synthesized the h-BN atomic layers with various C concentrations varying from 0 to 10.2 atom % by ion beam sputtering deposition through controlling the sputtering atmosphere. The h-BN phase remains stable when a small amount of C is incorporated into h-BN, whereas the introduction of a large amount of C impurities leads to the rapidly deteriorated crystallinity of h-BN. Furthermore, the DUV photodetectors based on C-doped h-BN layers were fabricated, and the h-BN-based photodetector with 7.5 atom % C exhibits the best performance with a responsivity of 9.2 mA·W^-1, which is significantly higher than that of the intrinsic h-BN device. This work demonstrates that the C doping is a feasible and effective method for improving the performance of h-BN photodetectors.

Two-dimensional hexagonal boron-carbon-nitrogen atomic layers

Two-dimensional (2D) hexagonal boron-carbon-nitrogen (h-BCN) atomic layers are expected to possess interesting properties complementary to those of graphene and h-BN, enabling a rich variety of electronic structures, properties and applications. Herein, we demonstrate a novel method to synthesize 2D h-BCN atomic layers with a full range of compositions by ion beam sputtering deposition under a mixed Ar/CH4 atmosphere. The h-BCN layers have been thoroughly characterized by various techniques, aiming at the determination of their structure evolution and properties. We find that homogeneous h-BCN layers consisting of graphene and h-BN nanodomains can be obtained at an appropriate C content, whereas too high or too low C contents result in the segregation of large-sized graphene or h-BN islands. Furthermore, the band gap of h-BCN layers slightly decreases with the increasing C content, while their electric properties can be tuned from insulating to highly conducting. This work provides a novel approach for synthesizing 2D h-BCN atomic layers and paves the way for the development of h-BCN-based devices.

Borocarbonitrides as Metal-Free Catalysts for the Hydrogen Evolution Reaction

Hydrogen generation by water splitting is clearly a predominant and essential strategy to tackle the problems related to renewable energy. In this context, the discovery of proper catalysts for electrochemical and photochemical water splitting assumes great importance. There is also a serious intent to eliminate platinum and other noble metal catalysts. To replace Pt by a non-metallic catalyst with desirable characteristics is a challenge. Borocarbonitrides, (B_x C_y N_z ) which constitutes a new class of 2D material, offer great promise as non-metallic catalysts because of the easy tunability of bandgap, surface area, and other electronic properties with variation in composition. Recently, B_x C_y N_z composites with excellent electrochemical and photochemical hydrogen generation activities have been found, especially noteworthy being the observation that B_x C_y N_z with a carbon-rich composition or its nanocomposites with MoS₂ come close to Pt in electrocatalytic properties, showing equally good photochemical activity.

Chemical vapor deposition growth of boron-carbon-nitrogen layers from methylamine borane thermolysis products

This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as the single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is a significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar composition.

Borocarbonitrides, BxCyNz: Synthesis, Characterization, and Properties with Potential Applications

Borocarbonitrides, B_xC_yN_z, constitute a new family of layered two-dimensional materials and can be considered to be derived from graphene. They can be simple composites containing graphene and BN domains or more complex materials possessing B-C and C-N bonds besides B-N and C-C bonds. Properties of these materials depend on the composition, and the method of synthesis, wherein one can traverse from the insulating end (BN) to the conducting end (graphene). In this article, we present an up-to-date review of the various aspects of borocarbonitrides including synthesis, characterization and properties. Some of the properties have potential applications, typical of them being in gas adsorption and energy devices such as supercapacitors, fuel cells and batteries. Performance of borocarbonitrides as catalysts in the electrochemical hydrogen evolution reaction is impressive. It is noteworthy that with certain compositions on borocarbonitrides, field-effect transistors can be fabricated.