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Keywords:
AgNPs, Fe3O4, bifunctional, SERS, NSAIDS

Abstract:
The rapidly growing production and usage of lithium-ion batteries (LIBs) dramatically raises the number of harmful wastes. Consequently, the LIBs waste management processes, taking into account reliability, efficiency, and sustainability criteria, became a hot issue in the context of environmental protection as well as the scarcity of metal resources. In this paper, we propose for the first time a functional material—a magnetorheological fluid (MRF) from the LIBs-based liquid waste containing heavy metal ions. At first, the spent battery waste powder was treated with acid-leaching, where the post-treatment acid-leaching solution (ALS) contained heavy metal ions including cobalt. Then, ALS was used during wet co-precipitation to obtain cobalt-doped superparamagnetic iron oxide nanoparticles (SPIONs) and as an effect, the harmful liquid waste was purified from cobalt. The obtained nanoparticles were characterized with SEM, TEM, XPS, and magnetometry. Subsequently, superparamagnetic nanoparticles sized 15 nm average in diameter and magnetization saturation of about 91 emu g−1 doped with Co were used to prepare the MRF that increases the viscosity by about 300% in the presence of the 100 mT magnetic fields. We propose a facile and cost-effective way to utilize harmful ALS waste and use them in the preparation of superparamagnetic particles to be used in the magnetorheological fluid. This work describes for the first time the second life of the battery waste in the MRF and a facile way to remove the harmful ingredients from the solutions obtained after the acid leaching of LIBs as an effective end-of-life option for hydrometallurgical waste utilization.

Keywords:
environment protection SPION, battery waste, toxic waste management, direct recycling, sustainability, circular economy, critical raw materials

Abstract:
Lithium-ion battery (LiB) waste powder is a valuable source of various materials, including carbon and metals. Although this material exhibits electrical conductivity, nanostructured morphology, and may contain metal oxides, it has not been used as an electrocatalyst. Here, we demonstrated the application of LiB waste powder as a catalyst for electrochemical H2O2 generation. The powder was both immobilized on a glassy carbon (GC) electrode and assembled at a liquid–liquid interface formed by decamethylferrocene (DMFc) solution in trifluorotoluene and aqueous perchloric acid in the presence of oxygen. The electrochemistry was studied by cyclic voltammetry and also with a rotating disk electrode (RDE), and a 2-electron ORR pathway was confirmed. H2O2 generation at the liquid–liquid interface and oxidation of DMFc were detected by colorimetry, UV–vis spectroscopy and scanning electrochemical microscopy (SECM). The use of LiB waste powder reduces the ORR onset potential by ca. 0.3 V compared to an unmodified GC. When assembled at a liquid–liquid interface the waste powder increases the efficiency of H2O2 generation by ca. 20 times.

Keywords:
hydrogen peroxide, lithium-ion battery waste, oxygen reduction, scanning electrochemical microscopy (SECM), liquid–liquid interface

Abstract:
In this work, novel W-Zr-B coatings were developed by a hybrid process combining pulsed laser deposited ZrB2 and radio frequency magnetron sputtered W2B5. The influence of the laser power density on the structure and mechanical properties of the deposited films was studied. Addition of zirconium causes a change in the structure of the deposited films from columnar to mainly amorphous. The nanoindentation tests and compression of nanopillars showed that doped W-Zr-B layers are still super-hard and incompressible in comparison to WB2 films without doping, but they change their behaviour from brittle to ductile. Films obtained with a fluence of 1.06 J/cm2 are superhard (H = 40 ± 4 GPa) and incompressible (12 ± 1 GPa), but possess a relatively low Young’s modulus (E = 330 ± 32 GPa) and a high elastic recovery (We = 0.9). Further increase in the fluence causes films to consist of deeply embedded fragments of laser ablated ZrB2 target in the deposited layer. Taking into account that the particles are made of ZrB2 which possess extraordinary thermal properties, and the matrix is made of W-Zr-B, a super-hard material, such a composite can also be interesting for industrial applications.

Keywords:
superhard tungsten borides, hybrid magnetron sputtering – pulsed laser deposition, nanopillar compression

Abstract:
In this work, (W,Ti)B2 films with different stoichiometric ratio Ti/W deposited on silicon and 304 stainless steel by radio frequency magnetron sputtering are presented. The coatings were deposited from plasma spark sintered targets obtained from the mixture of pure boron, tungsten and titanium powders. It is shown that during plasma spark sintering process using overstoichiometric boron and a low content of titanium change the WB2 to WB4 phase with almost no secondary phases. Subsequently, the impact of titanium content on the films properties is investigated systematically, including the chemical and phase composition, crystalline structure, surface and cross-section morphology. Simultaneously, nano-indentation test and ball-on-disk tribometery are performed to analyse the hardness and tribological properties of the films. It is shown that deposited films with titanium content of 3.6 and 5.5 at.% are formed in the zone T of the Thornton's Structural Zone Model. In opposite to α-WB2 magnetron sputtered coatings they are more flexible and hard nanocomposite coatings. The results show that the addition of titanium is apparently changing the film structure from nanocrystalline columnar to amorphous, very dense and compact structure with the addition of TiB2 phase. That films are simultaneously hard (H > 37.5 GPa), have high hardness to effective Young's modulus ratio values (H/E* > 0.1) and elastic recovery (We > 60%) appropriate for tough and resistant to cracking materials. The presented (W,Ti)B2 films exhibit also tribological and corrosion properties better than unalloyed coatings.

Keywords:
superhard films, ternary tungsten borides, RF magnetron sputtering, wear resistance, corrosion