Oxygen defects-engineered LaFeO3-x nanosheets as efficient electrocatalysts for lithium-oxygen battery

Preparation of visible-light active MOFs-Perovskites (ZIF-67/LaFeO3) nanocatalysts for exceptional CO2 conversion, organic pollutants and antibiotics degradation

Modern industries rapid expansion has heightened energy needs and accelerated fossil fuel depletion, contributing to global warming. Additionally, organic pollutants present substantial risks to aquatic ecosystems due to their stability, insolubility, and non-biodegradability. Scientists are currently researching high-performance materials to address these issues. LaFeO3 nanosheets (LFO-NS) were synthesized in this study using a solvothermal method with polyvinylpyrrolidone (PVP) as a soft template. The LFO-NS demonstrate superior performance, large surface area and charge separation than that of LaFeO3 nanoparticles (LFO-NP). The LFO-NS performance is further upgraded by incorporating ZIF-67. Our results confirmed the ZIF-67/LFO-NS nanocomposite have superior performances than pure LFO-NP and ZIF-67. The integration of ZIF-67 has enhanced the charge separation and promote the surface area of LFO-NSwhich was confirmed by various characterization techniques including TEM, HRTEM, DRS, EDX, XRD, FS, XPS, FT-IR, BET, PL, and RAMAN. The 5ZIF-67/LFO-NS sample showed significant activities for CO2 conversion, malachite green degradation, and antibiotics (cefazolin, oxacillin, and vancomycin) degradation. Furthermore, stability tests have confirmed that our optimal sample very active and stable. Furthermore, based on scavenger experiments and the photocatalytic degradation pathways, it has been established that H+ and •O2- are vital in the decomposition of MG and antibiotics. Our research work will open new gateways to prepare MOFs-Perovskites nanocatalysts for exceptional CO2 conversion, organic pollutants and antibiotics degradation.

Recent Status and Developments of Vacancies Modulation in the ABO3 Perovskites for Catalytic Applications

Perovskite oxides (ABO₃ ) have attracted comprehensive interest for wide range of functional applications (especially for chemical catalysis) due to their high design flexibility, controllable vacancies sites creation, abundant chemical properties, and stable crystal structure. Herein, the previous research and potential development of ABO₃ through adjusting the vacancy at different sites (A-site, B-site, and O-site) to enhance catalytic performance are systematically analyzed and generalized. Briefly, the ABO₃ with different vacancies sites prepared by multifarious direct and indirect methods, accompanied with the improved physical-chemical properties, endow them with distinct and intensified development of catalysis application. In addition, the impressive optimization proved by the vacancies sites adjustment over the ABO₃ is studied to continuously facilitate the advance in some common catalysis reactions, further expanding to other optimized functional applications. At last, the constructive suggestions for fine regulation and analysis of vacancies sites over ABO₃ are also put forward.

Elucidation of a mechanism for the heterogeneous electro-fenton process and its application in the green treatment of azo dyes

Vast efforts are directed today toward the development of efficient, green methods for the degradation of toxic compounds, especially those that are water-soluble. Though Fenton reactions are commonly used in wastewater treatment, their mechanisms and the active species involved remain obscure due to their mechanistic complexity. In this work, the mechanism of an electro-Fenton reaction, in which a FeLaO₃ catalyst was entrapped in a sol-gel matrix, was studied in the presence of azo dyes as the model for toxic compounds. Increased knowledge about this important mechanism will confer greater control over related processes and enable a more efficient and green degradation method. DFT calculations showed that in the presence of Fe(IV), OH are formed under acidic conditions and that both the iron and hydroxyl species function as oxidation reagents in the degradation process. The structure of the formed Fe(IV) embedded in the solid matrix was not the typical tetravalent structure. Entrapment in the sol-gel matrix stabilized the catalyst, enhanced its efficiency and enabled it to be recycled. Sol-gel matrices constitute a simple method for the degradation of stable and toxic compounds under extreme pH conditions. The findings of this study are highly significant for the treatment of typically acidic wastewaters.

Atomically Dispersed Transition Metal-Nitrogen-Carbon Bifunctional Oxygen Electrocatalysts for Zinc-Air Batteries: Recent Advances and Future Perspectives

Rechargeable zinc-air batteries (ZABs) are currently receiving extensive attention because of their extremely high theoretical specific energy density, low manufacturing costs, and environmental friendliness. Exploring bifunctional catalysts with high activity and stability to overcome sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction is critical for the development of rechargeable ZABs. Atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts possessing prominent advantages of high metal atom utilization and electrocatalytic activity are promising candidates to promote oxygen electrocatalysis. In this work, general principles for designing atomically dispersed M-N-C are reviewed. Then, strategies aiming at enhancing the bifunctional catalytic activity and stability are presented. Finally, the challenges and perspectives of M-N-C bifunctional oxygen catalysts for ZABs are outlined. It is expected that this review will provide insights into the targeted optimization of atomically dispersed M-N-C catalysts in rechargeable ZABs.

Influence of the Amount of Carbon during the Synthesis of LaFe0.8Co0.2O3/Carbon Hybrid Material in Oxygen Evolution Reaction

The oxygen evolution reaction (OER) and the hydrogen evolution reaction occurred at the anode and cathode, which depends on the electronic structure, morphology, electrochemically active surface area, and charge-transfer resistance of the electrocatalyst. Transition metals like cobalt, nickel, and iron have better OER and oxygen reduction reaction activities. At the same time, transition-metal oxide/carbon hybrid has several applications in electrochemical energy conversion reactions. The rich catalytic site of transition metals and the excellent conductivity of carbon material make these materials as a hopeful electrocatalyst in OER. Carbon-incorporated LaFe_0.8Co_0.2O₃ was prepared by a simple solution combustion method for the development of the best performance of the electrocatalyst. The catalyst can deliver 10 mA/cm² current density at an overpotential of 410 mV with better catalytic stability. The introduction of carbon material improves the dispersion ability of the catalyst and the electrical conductivity. The Tafel slope and onset potential of the best catalyst are 49.1 mV/dec and 1.55 V, respectively.

A novel LaFeO3 catalyst synthesized from sodium diethylenetriamine pentamethylene phosphonate for degradation of diclofenac through peroxymonosulfate activation: degradation pathways and mechanism study

A series of LaFeO3 catalysts were prepared using the sol–gel method with sodium diethylenetriamine pentamethylene phosphonate as the complexing agent and were applied to activate PMS to produce active oxides to degrade DCF.

Defect Engineering of Carbon-based Electrocatalysts for Rechargeable Zinc-air Batteries

Rechargeable zinc-air batteries (ZABs) are considered as one of the most promising electrochemical energy devices due to their various unique advantages. Oxygen electrocatalysis, involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), determines the overall performance of zinc-air batteries. Therefore, the development of highly efficient bifunctional ORR/OER catalysts is critical for the large-scale application of ZABs. Carbon-based nanomaterials have been widely reported to be efficient electrocatalysts toward both ORR and OER. The enhanced activity of these electrocatalysts are usually attributed to different doping defects, synergistic effects and even the intrinsic carbon defects. Herein, an overview of the defect engineering in carbon-based electrocatalysts for ORR and OER is provided. The different types of intrinsic carbon defects and strategies for the generation of other defects in carbon-based electrocatalysts are presented. The interaction of heteroatoms doped carbon and transition metals (TMs) is also explored. In the end, the existing challenges and future perspectives on defect engineering are discussed.