Cu₂O-promoted degradation of sulfamethoxazole by <i>α</i>-Fe₂O₃-catalyzed peroxymonosulfate under circumneutral conditions: synergistic effect, Cu/Fe ratios, and mechanisms

<p>To promote the application of iron oxides in sulfate radical-based advanced oxidation processes, a convenient approach using Cu₂O as a catalyst additive was proposed. Composite catalysts based on <i>α</i>-Fe₂O₃ (CTX%Cu₂O, <i>X</i> = 1, 2.5, 5, and 10) were prepared for peroxymonosulfate (PMS) activation, and sulfamethoxazole was used as a model pollutant to probe the catalytic reactivity. The results show that a synergistic catalytic effect exists between Cu₂O and <i>α</i>-Fe₂O₃, which was explained by the promoted reduction of Fe(III) by Cu(I). Iron K-edge X-ray absorption spectroscopy investigations indicated that the promoted reduction probably occurred with PMS acting as a ligand that bridges the redox centers of Cu(I) and Fe(III). The weight ratio between Cu₂O and <i>α</i>-Fe₂O₃ influenced the degradation of sulfamethoxazole, and the optimal ratio depended on the dosage of PMS and catalysts. With 40 mg L^–1 PMS and 0.6 g L^–1 catalyst, a pseudo-first-order constant of ∼0.019 min^–1 was achieved for CT2.5%Cu₂O, whereas only 0.004 min^–1 was realized for <i>α</i>-Fe₂O₃. Nearly complete degradation of the sulfamethoxazole was achieved within 180 min under the conditions of 40 mg L^–1 PMS, 0.4 g L^–1 CT2.5%Cu₂O, and pH 6.8. In contrast, less than 20% degradation was realized with <i>α</i>-Fe₂O₃ under similar conditions. The CT2.5%Cu₂O catalyst had the best stoichiometric efficiency of PMS (0.317), which was 4.5 and 5.8 times higher than those of Cu₂O (0.070) and <i>α</i>-Fe₂O₃ (0.054), respectively. On the basis of the products identified, the cleavage of the S–N bond was proposed as a major pathway for the degradation of sulfamethoxazole.</p

Metallurgy Inspired Formation of Homogeneous Al₂O₃ Coating Layer To Improve the Electrochemical Properties of LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Material

Inspired by the metallurgical process of aluminum production, a controllable and cost-effective Al₂O₃ coating strategy is introduced to improve the surface stability of LiNi_0.8Co_0.1­Mn_0.1O₂. The CO₂ is introduced to NaAlO₂ aqueous solution to generate a weak basic condition that is able to decrease the deposition rate of Al­(OH)₃ and is beneficial to the uniform coating of Al­(OH)₃ on the surface of commercial Ni_0.8Co_0.1­Mn_0.1(OH)₂ precursor. The electrochemical performance of Al₂O₃-coated LiNi_0.8Co_0.1­Mn_0.1O₂ is improved at both ordinary cutoff voltage of 4.3 V and elevated cutoff voltage of 4.5 V. With the optimized Al₂O₃ coating amount (1%), the capacity retention of the material after 60 cycles increases from 90% to 99% at 2.8–4.3 V and from 86% to 99% at 2.8–4.5 V, respectively. The Al₂O₃-coated sample also delivers a better rate capability, maintaining 117 and 131 mA h g^–1 in the voltage ranges 2.8–4.3 and 2.8 V–4.5 V at the current density of 5 C, respectively. The enhanced properties of as-prepared Al₂O₃-coated LiNi_0.8Co_0.1Mn_0.1O₂ are due to the Al₂O₃ coating layer building up a favorable interface, preventing the direct contact between the active material and electrolyte and promoting Li⁺ transmission at the interface

Annealing-Induced Antibacterial Activity in TiO₂ under Ambient Light

We demonstrate that annealing at 850 °C in the presence of Cu universally results in robust antibacterial activity under ambient illumination for TiO₂ nanoparticles, different from those annealed in a quartz crucible without metal or in the presence of Ti. Resulting robust antibacterial activity occurred after annealing regardless of the initial properties and crystal structure of the starting samples (two anatase, one rutile, and P25). A clear difference in the powder color from white to gray and a pure rutile crystal structure is observed after annealing in all of the samples. ESR measurements, however, reveal obvious differences in the defects present in the samples annealed under different conditions. Strong antibacterial activity is observed under ambient illumination for samples annealed in the presence of Cu, despite the lower activity for photocatalytic degradation of common dyes such as methylene blue after annealing. Antibacterial activity could not be attributed to the presence of Cu (no activity in the dark) or to the ROS production (none detected under ambient illumination). This indicates that other mechanisms, such as direct charge transfer involving defect levels induced by annealing in the presence of copper, may play a role in the observed antibacterial activity

Synthesis of Lead-Free Perovskite Films by Combinatorial Evaporation: Fast Processes for Screening Different Precursor Combinations

We demonstrate an evaporation-based combinatorial approach for fast screening of precursor combinations for the synthesis of novel perovskite materials. Nine material combinations can be explored simultaneously, which enabled us to synthesize nine different lead-free perovskite compounds. The structural properties (morphology, crystal structure) and optical properties (UV–vis absorption spectra, photoluminescence) of the prepared materials were investigated. Among these materials, several Sn-based and Pd-based perovskites exhibit strong absorption in the visible spectral range and thus may be of interest for photovoltaic applications. In addition, butyl ammonium tin iodide exhibits bright red emission, and it is of interest for potential light emitting applications