Recent advances of modification effect in Co3O4-based catalyst towards highly efficient photocatalysis

Tricobalt tetroxide (Co3O4) has been developed as a promising photocatalyst material for various applications. Several reports have been published on the self-modification of Co3O4 to achieve optimal photocatalytic performance. The pristine Co3O4 alone is inadequate for photocatalysis due to the rapid recombination process of photogenerated (PG) charge carriers. The modification of Co3O4 can be extended through the introduction of doping elements, incorporation of supporting materials, surface functionalization, metal loading, and combination with other photocatalysts. The addition of doping elements and support materials may enhance the photocatalysis process, although these modifications have a slight effect on decreasing the recombination process of PG charge carriers. On the other hand, combining Co3O4 with other semiconductors results in a different PG charge carrier mechanism, leading to a decrease in the recombination process and an increase in photocatalytic activity. Therefore, this work discusses recent modifications of Co3O4 and their effects on its photocatalytic performance. Additionally, the modification effects, such as enhanced surface area, generation of oxygen vacancies, tuning the band gap, and formation of heterojunctions, are reviewed to demonstrate the feasibility of separating PG charge carriers. Finally, the formation and mechanism of these modification effects are also reviewed based on theoretical and experimental approaches to validate their formation and the transfer process of charge carriers.

Anchoring 1D nanochain-like Co3O4 on a 2D layered Ti3C2Tx MXene with outstanding electromagnetic absorption

3D superstructure Ti3C2Tx/Co3O4 nanochain composites were synthesized through electrostatic self-assembly, in which 1D Co3O4 nanochains were anchored on a 2D layered Ti3C2Tx surface.

Sol-gel synthesis and characterization of Co3O4/CeO2 nanocomposites and its application for photocatalytic discoloration of organic dye from aqueous solutions

Herein, Co₃O₄/CeO₂ nanocomposite was synthesized by the modified Pechini method. Citric, maleic, succinic, and trimsic acids were used as a stabilizer, and the variation affected the morphology and size of the synthesized nanocomposites. Subsequently, the formation of Co₃O₄/CeO₂ nanocomposites was confirmed by various analyses. Furthermore, the particles were considered for size and morphology by SEM and HRTEM analyses, and the sample that used trimsic acid as the stabilizer was designated as the goal sample to continue the route. The optimum sample was used to investigate the photocatalytic properties of the synthesized nanocomposite. The UV-light photocatalyst test was performed in neutral, alkaline, and acidic states against two aqueous solutions containing color contamination of methylene blue and erythrosine B dyes. The results showed decolorization at 85% for methylene blue and 90% for erythrosine B over 120 min test time.

Fabrication of chlorambucil loaded graphene- oxide nanocarrier and its application for improved antitumor activity

The present study aims at designing a biodegradable and biocompatible nanocarrier using gelatin and reduced graphene oxide nanosheets functionalized with folic acid, for release of chlorambucil drug in controlled manner and achieving high loading efficiency. From scanning electron microscopic studies small pore like structure with rough and thick morphology on the plane of graphene oxide is clearly visible indicating high loading of drug. Further, Drug loading and encapsulation efficiency, in vitro release studies of the drug from the nanocarrier at different concentrations of reduced graphene oxide, different pH were studied. The mean particle size, entrapment efficiency (%) of optimized folic acid functionalized gelatin-graphene oxide formulation was observed to be 300 nm and 56% respectively. From the release studies it is clear that, after 24 h the release rate of the drug was found to be higher at acidic conditions compared to neutral conditions. It was found that 62.1% and 82% of the total bound drug was released from the nanocarrier at pH 5.4 and pH 1.2 respectively. Besides, under neutral conditions (pH 7.4), 43.7% of the total bound drug was released from the nanocarrier in the first 24 h. The % cell viability of free drug, drug loaded nanocomposites against human cervical adenocarcinoma cell line was found to be 11.7% and 28% respectively at the dose of 500 μg mL^-1 after 24 h. IC50 values also manifest the significantly lower cytotoxicity of drug loaded nanocarrier (IC50 = 125.9 μg/mL) as compared to free-drug (IC50 = 86 μg/mL). For FAGGO, CLB and CLB-FAGGO the values of mean ± std. deviation were found to be 71.80 ± 6.66; 48.71 ± 23.15; 55.48 ± 19.65 respectively. The unique properties exhibited by biodegradable polymer like gelatin and carbon based materials such as graphene offers an excellent applications in biomedical field.

Sonochemical synthesis of Pr6MoO12 nanostructures as an effective photocatalyst for waste-water treatment

Synthesis of pure Pr₆MoO₁₂ nanoparticles was the aim of the present work, which was prepared by sonochemical method which is a controllable rout on size, purity, and morphology of products. The experiments were carried out under a probe as sonication source, and its power was adjusted in 30 W (9 kHz), 50 W (15 kHz), and 80 W (24 kHz) for different samples. The optimum product with the smallest size and highest purity was synthesized by changing time, power of sonication, solvent and capping agent. Besides, the formation of various phases of praseodymium molybdate was investigated in different experimental conditions that proved the presence of ammonia, sonication and calcination are necessary factors for the preparation of pure Pr₆MoO₁₂ nanoparticles. Products were characterized by various analyses such as SEM, XRD, TEM, FT-IR, DRS, and EDS. Furthermore, the photocatalytic activity of Pr₆MoO₁₂ nanoparticles under UV irradiation was studied by photodegradation of methylene blue and acid red 92 as organic pollutants. The most active photocatalytic agent was determined superoxide anion radicals and kinetics model of photocatalytic reaction was considered as pseudo-first order.

Investigation of experimental and instrumental parameters on properties of PbFe12O19 nanostructures prepared by sonochemical method

It is the first time that PbFe₁₂O₁₉ nanostructures were successfully synthesized by sonochemical method. The instrumental and experimental parameters were optimized to achieve the appropriate product. The results showed that Pb⁺² to Fe⁺³ molar ratio and the type of capping agent as experimental parameters and time and power of sonication as instrumental variables can influence on the purity and particle size of products, respectively. According to the results, the synthesis process could improve to sol-gel assisted sonochemical method in presence of PEG as capping agent. In this method, pure product obtained by using the high temperature and pressure in sonication treatment and hydrolysis and condensation processes in sol-gel method, simultaneously. Concurrent presence of sonication treatment and PEG were necessary for preparation of pure hexaferrite nanostructures. Because of metal oxides nanostructures as major product and hexaferrite as minor product were produced in the absence of them. So, sol-gel assisted sonochemical method can be introduced as an effective method for preparation of hexaferrite nanostructures. Furthermore, it was found that the instrumental parameters should be optimized, because of increasing the time and power of sonication is not always favorable for preparation of ultrafine particles and small structures.

Co-doped TiO2 nanostructures as a strong antibacterial agent and self-cleaning cover: Synthesis, characterization and investigation of photocatalytic activity under UV irradiation

The aim of this work was synthesis and investigation of various properties of Co-doped titanium dioxide nanostructures. However, dopant has no effect on XRD pattern of the host but it can influence on the various characteristics of host such as optical and electrical properties. The results of optical properties showed that absorption energy of TiO₂ decreases in presence of cobalt as dopant. Red-shift in absorption spectrum that may be due to the excitation of 3d electrons of Co ions to the conduction band of TiO₂ can be considered as a strong evidence to confirm the presence of Co as dopant in TiO₂ lattice. Photocatalytic activity of products was examined by degradation of three dyes including: Acid Red 1 (A.R.1.), Reactive Blue 21 (R.A.21.) and Acid Blue 74 (A.B.74.) under UV irradiation and antibacterial activity of this product was tested by inhibition of the growth of three bacteria: Pseudomonas aeruginosa, S. aureus and E. coli. High percent of dye degradation and decreasing the contact angle of surfaces in the presence of this product as a cover confirm that Co-doped TiO₂ can be used as a self-cleaning cover on various surfaces. The antibacterial activity is another property of this product as an antibacterial agent.

Magnetite hybrid photocatalysis: advance environmental remediation

One of the main public concerns is the aquatic habitat and its corresponding issues because of the incessant contamination of the ecological water systems. In recent years, research attention has been focused on processes that lead to an improved oxidative degradation of organic pollutants. Therefore, semiconductor photocatalysis technology has aroused scientists’ interest in environmental remediation. Although several semiconductors have proven to be ideal candidates for the treatment of water pollution, the efficient separation and recycling of this fine-powdered photocatalyst is still a scientific problem when applied in practice, including separation process, selectivity, and dispersion. A photocatalyst with magnetic properties allows the use of the technique of magnetic separation, which is one of the most effective and simple methods for removing suspended solids from wastewater without the need for further separation processes. The magnetic photocatalyst allows its use as a suspended material, providing the advantage to have a high surface area for reaction. This review highlights the advantages and disadvantages of current photocatalyst systems. Moreover, it focuses on hybrid magnetic photocatalysts, including metals and nonmetals, metal oxides, carbon-based materials, and ceramics.