Corrosion resistance evaluation of boron-carbon coating on ASTM A-36 steel

The ASTM A-36 steel is the main alloy, used in the metal-mechanical industry. In the present study, the effect of boron-carbon coating on the hardness and corrosion resistance of the steel ASTM A-36 was reported. Boronizing thermochemical treatment was carried out at 950 °C for 4 h followed by the carburizing process at 930 °C for 6 h. The corrosion study was conducted using the polarization technique (Tafel) and electrochemical impedance spectroscopy (EIS), which employed a fused deposition modeling-based 3D printing electrochemical cell made of polylactic acid (PLA). A commercial platinum foil and an Ag/AgCl (3.5 M KCl) electrode were used as the counter and reference electrode, respectively. The working electrode used an area of 1 cm2 of the sample. Optical microscopic analysis shown that borides formed on the surface of steels has a saw-tooth morphology and a uniform coating with a thickness of about 60 µm in both samples. The carburizing over boride promoted the formation of coatings on the outermost layer of the samples with a thickness of about 17 µm over the boride layer. Boride formation was verified by X-ray diffraction (XRD) analysis indicating only the formation of the Fe2B phase. Results showed that boride samples exhibited inferior corrosion resistance compared to original samples, but after carburizing, an outer layer was formed, with the hardness and corrosion resistance like that of the original sample.

Boron Carbon Oxynitride as a Novel Metal-Free Photocatalyst

Boron-based nanomaterials are emerging as non-toxic, earth-abundant (photo)electrocatalyst materials in solar energy conversion for the production of solar hydrogen fuel and environmental remediation. Boron carbon oxynitride (BCNO) is a quaternary semiconductor with electronic, optical, and physicochemical properties that can be tuned by varying the composition of boron, nitrogen, carbon, and oxygen. However, the relationship between BCNO's structure and -photocatalytic activity relationship has yet to be explored. We performed an in-depth spectroscopic analysis to elucidate the effect of using two different nitrogen precursors and the effect of annealing temperatures in the preparation of BCNO. BCNO nanodisks (D = 6.7 ± 1.1 nm) with turbostratic boron nitride diffraction patterns were prepared using guanidine hydrochloride as the nitrogen source precursor upon thermal annealing at 800°C. The X-ray photoelectron spectroscopy (XPS) surface elemental analysis of the BCNO nanodisks revealed the B, C, N, and O compositions to be 40.6%, 7.95%, 37.7%, and 13.8%, respectively. According to the solid-state 11B NMR analyses, the guanidine hydrochloride-derived BCNO nanodisks showed the formation of various tricoordinate BNx(OH)3−x species, which also served as one of the photocatalytic active sites. The XRD and in-depth spectroscopic analyses corroborated the preparation of BCNO-doped hexagonal boron nitride nanodisks. In contrast, the BCNO annealed at 600 °C using melamine as the nitrogen precursor consisted of layered nanosheets composed of B, C, N, and O atoms covalently bonded in a honeycomb lattice as evidence by the XRD, XPS, and solid-state NMR analysis (11B and 13C) analyses. The XPS surface elemental composition of the melamine-derived BCNO layered structures consisted of a high carbon composition (75.1%) with a relatively low boron (5.24%) and nitrogen (7.27%) composition, which indicated the formation of BCNO-doped graphene oxides layered sheet structures. This series of melamine-derived BCNO-doped graphene oxide layered structures were found to exhibit the highest photocatalytic activity, exceeding the photocatalytic activity of graphitic carbon nitride. In this layered structure, the formation of the tetracoordinate BNx(OH)3−x(CO) species and the rich graphitic domains were proposed to play an important role in the photocatalytic activity of the BCNO-doped graphene oxides layered structures. The optical band gap energies were measured to be 5.7 eV and 4.2 eV for BCNO-doped hexagonal boron nitride nanodisks and BCNO-doped graphene oxides layered structures, respectively. Finally, BCNO exhibited an ultralong photoluminescence with an average decay lifetime of 1.58, 2.10, 5.18, and 8.14 µs for BGH01, BGH03, BMH01, BMH03, respectively. This study provides a novel metal-free photocatalytic system and provides the first structural analysis regarding the origin of BCNO-based photocatalyst. Graphical Abstract

Surface Functionalization of Boron-Carbon BС5 Nanotubes by a Nitro Group As a Sensor Device Element: Theoretical Research

The problem of modification of boron-carbon nanotubes (BCNT) by functional groups is relevant in connection with the intensive development of the nano industry, in particular, nano- and microelectronics. For example, a modified nanotube can be used as an element of a sensor device for detecting microenvironments of various substances, in particular metals included in salts and alkalis. The paper discusses the possibility of creating a high-performance sensor using single-layer boron-carbon nanotubes as a sensitive element, the surface of which is modified with a functional nitro group -NO2. Quantum-chemical studies of the process of attaching a nitro group to the outer surface of a single-layer boron-carbon nanotube (BCNT) of type (6, 6) were carried out, which proved the possibility of modifying the BCNT and the formation of a bond between the group -NO2 and the carbon atom of the surface of the nanotube. The results of computer simulation of interaction of surface-modified boron-carbon nanotube with alkali metal atoms (lithium, sodium, potassium) are presented. The sensory interaction of the modified boron-carbon nanosystem with the selected metal atoms was investigated, which proved the possibility of identifying these atoms using a nanotubular system that can act as an element of the sensor device. When reacting with alkali metal atoms in the “BСNT+NO 2” complex, the number of basic carriers increases, due to the transfer of electron density from metal atoms to modified BСNT. The results presented in this paper were obtained using the molecular cluster model and the calculated DFT method with exchange-correlation functionality B3LYP (valence-split basis set 6-31G).

Polymer-Coated Nanoparticles for Therapeutic and Diagnostic Non-10B Enriched Polymer-Coated Boron Carbon Oxynitride (BCNO) Nanoparticles as Potent BNCT Drug

Boron neutron capture therapy (BNCT) is a powerful and selective anti-cancer therapy utilizing 10B-enriched boron drugs. However, clinical advancement of BCNT is hampered by the insufficient loading of B-10 drugs throughout the solid tumor. Furthermore, the preparation of boron drugs for BNCT relies on the use of the costly B-10 enriched precursor. To overcome these challenges, polymer-coated boron carbon oxynitride (BCNO) nanoparticles, with ~30% of boron, were developed with enhanced biocompatibility, cell uptake, and tumoricidal effect via BNCT. Using the ALTS1C1 cancer cell line, the IC50 of the PEG@BCNO, bare, PEI@BCNO were determined to be 0.3 mg/mL, 0.1 mg/mL, and 0.05 mg/mL, respectively. As a proof-of-concept, the engineered non-10B enriched polymer-coated BCNO exhibited excellent anti-tumor effect via BNCT due to their high boron content per nanoparticle and due to the enhanced cellular internalization and retention compared to small molecular 10B-BPA drug. The astrocytoma ALTS1C1 cells treated with bare, polyethyleneimine-, and polyethylene glycol-coated BCNO exhibited an acute cell death of 24, 37, and 43%, respectively, upon 30 min of neutron irradiation compared to the negligible cell death in PBS-treated and non-irradiated cells. The radical approach proposed in this study addresses the expensive and complex issues of B-10 isotope enrichment process; thus, enabling the preparation of boron drugs at a significantly lower cost, which will facilitate the development of boron drugs for BNCT.