Search

Synergistic integration between carbon matrix and 2D MXene brings up great creativity towards more opportunity of versatile serving scenario for MXene-based hybrid materials, especially in realms like electrochemical energy storage, photo-/electrocatalysis water splitting, electromagnetic waves adsorption, sensing and so on. Multidimensional carbonaceous matrix, from zero-dimension (0D) to larger scales of 3D counterparts, building various heterostructure configuration with 2D MXene, could cultivate personas for different targets and further maximizing MXene intrinsic strength of in terms of layered structure and unique properties. In our review, we present a comprehensive discussion on miscellaneous structural integration of carbon matrix and MXene, including designing principles, synthetic routes, as well as internal correlation between two components. Meanwhile, we analyze and elaborate the textural features and structure–property relationships of 2D MXene-based composites with 0D, 1D, 2D and 3D multidimensional carbon matrix. At last, to fulfill future development and application foreground, we put forward subsistent challenge and noteworthy research perspectives of MXene-based and corresponding hybridization with carbonaceous matrix with different dimensionalities. [ABSTRACT FROM AUTHOR]

An optimal performance of bone implants with bioceramic coatings is closely related to the surface modification technology. For the first time, we have evaluated a gas detonation deposition (GDD) approach to obtain biocompatible ceramic coatings based on bioglass (BG) and calcium phosphates on Ti-based alloys as prospective materials towards their application for the development of bone implants. For the production of the coatings, hydroxyapatite (HA), HA metal-substituted (containing Ag+, Cu2+, or Zn2+) and tricalcium phosphate (TCP) were synthesized and characterized. Pure powders and their combination with BG were used to obtain coatings on a Ti–6Al–4V alloy using the developed automatized GDD setup. The microstructure, phase and chemical composition of the produced coatings were studied using XRD, SEM-EDS and Raman spectroscopy. The produced coated materials were evaluated in vivo in Wistar rats to analyze a reparative osteogenesis over a period of 12 weeks. The results regarding the optimization of the GDD method indicate its high productivity, as confirmed by high deposition rates. The highest deposition rate was observed for the coatings obtained from the HA metal-substituted powders. The results revealed a partial transformation of a HA phase to an α-TCP phase during the deposition, with a prevalence of the HA-phase in the coatings. According to the histological evaluation, the reparative osteogenesis occurs through the perimeter of the titanium implants, whereas the regeneration level increases from the 4th to the 12th week. The highest osteointegration level was detected for the implants coated with a biocomposite consisting of BG, HA and TCP. The results of the current study demonstrate an effectiveness of the GDD method to produce biocompatible coatings on Ti-based alloys. This provides excellent prerequisites towards the application and standardization of the GDD technology to manufacture bone implants for bone fixation and defect replacement, as well as the development of dental implants. [ABSTRACT FROM AUTHOR]

The creation of carbon matrices with a high surface area for effective catalytic activity is an urgent task today, especially in the field of electrocatalysis. In this study, microporous carbon (MPS) with a surface area of about 1300 m2 g−1 was produced from raw plant waste (apricot pit shells) by successive thermal carbonation and chemical treatment. The MPS was impregnated with H 2 PdCl 6 and calcined at various temperatures under a H 2 –Ar flux. The obtained Pd-NP@MPC (nanoparticle size from 1 to 25 nm) catalysts were characterized in detail by XRD, SEM, TEM and BET methods. Electrochemical tests show that the prepared composites exhibit high electrocatalytic activity and remarkable stability over time (over 50 h) for the HER process and overall water splitting performance. The electrodes have very low overpotentials (η) of 95–117 mV for HER in 1 M KOH at a current density of 100 mA cm−2. Furthermore, the Pd-NP@MPC-300 electrode can reach a high current density of 300 mA cm−2 at η merely of 170 mV and shows excellent electrocatalytic stability in prolonged water electrolysis. The relationships between MPC matrix characteristics, Pd NPs size and electrocatalytic properties are discussed in this paper. [Display omitted] • Microporous carbon (surface area ~1300 m2 g−1) was produced from apricot pit shells. • The Pd-NP@MPC composites (NPs 1–25 nm) exhibited superior HER in alkaline media. • The overpotentials of 95–117 mV for HER at a current density of 100 mA cm−2. • High catalytic activity remains well even after 50 h of continuous electrolysis. [ABSTRACT FROM AUTHOR]

Powder samples of Cr3+-doped δ*-Al 2 O 3 with particles sizes of 10–70 nm were obtained by combustion method. It is shown for the first time that Cr3+ ions in the δ*-Al 2 O 3 occupy octahedral sites in the bulk and at the surface of the nanosized particles. The photoluminescence spectra of Cr3+ in δ*-Al 2 O 3 consist of several relatively narrow lines (R-lines luminescence) in the 680–720 nm range, which are due to the 2E g → 4A 2g transitions. The local structure around Cr3+ ions inside the nanoparticles is shown to differ from that of Cr3+ located in the surface layer, which results in essential differences in the full width at half maximum values (14 cm−1 vs. 39 cm−1 at 77 K) and in red shift of the R-lines with increasing temperature from 77 to 293 K (20 cm−1 vs. ~11 cm−1). It was found that the Cr3+-doped δ*-Al 2 O 3 exhibits some striking features, including an unexpectedly high crystal-field strength at the interior Cr3+ site and an unusually high concentration of surface Cr3+ centers. Possible reasons for these features are discussed. The results obtained are anticipated to be useful for the monitoring of processes involved in the preparation of ceramics and composites based on Al 2 O 3 :Cr3+. [Display omitted] • The luminescent properties of Сr3+ in nanosized δ*-Al 2 O 3 are analyzed. • Two types of Сr3+ related centers (regular and surface) are observed. • In the 77–293 K range, all the Cr3+centers show emissions of the 2E g.→4A 2g type. • Structural disorder degree as a notable characteristic of Al 2 O 3 polymorphs. [ABSTRACT FROM AUTHOR]

A controlled bioleaching strategy to embed Ni 3 S 2 nanocrystals into 1D hollow carbonaceous fibers derived from renewable biomass was designed with enough inner voids as well as abundant natural pyridinic and pyrrolic nitrogen. The hollow fiber-based electrode can prevent the large volume expansion, improve the electronic conductivity and enhance the diffusion rate of Li+/Na+ ion. As a result, the synthesized Ni 3 S 2 /hollow carbonaceous fiber electrodes deliver excellent reversible capacity and outstanding cycle stability, i.e., 673.4 mAh g−1 at 0.1 A g−1 after 100 cycles for lithium-ion batteries (LIBs), 378.4 mAh g−1 at 1 A g−1 after 100 cycles for sodium-ion batteries (SIBs), in electrochemical half-cells. More importantly, a superior electrochemical performance is obtained in a full-cell when employing Na 3 V 2 (PO 4) 3 as cathode (i.e., 218.9 mAh g−1 after 100 cycles at 0.5 A g−1). Image 1 • A novel controlled bioleaching template-free approach to synthesize tunable hollow Ni 3 S 2 carbonaceous fibers. • 1D hollow carbonaceous fibers provide enough inner voids, abundant natural pyridinic and pyrrolic nitrogen. • The composites exhibit excellent lithium/sodium-ion storage performance for Half/Full Cell Applications. [ABSTRACT FROM AUTHOR]