A sol-gel synthesis to prepare size and shape-controlled mesoporous nanostructures of binary (II-VI) metal oxides

Emerging Trends in Zinc Ferrite Nanoparticles for Biomedical and Environmental Applications

Over the last few decades, the application of nanoparticles (NPs) gained immense attention towards environmental and biomedical applications. NPs are ultra-small particles having size ranges from 1 to 100 nm. NPs loaded with therapeutic or imaging compounds have proved a versatile approach towards healthcare improvements. Among various inorganic NPs, zinc ferrite (ZnFe2O4) NPs are considered as non-toxic and having an improved drug delivery characteristics . Several studies have reported broader applications of ZnFe2O4 NPs for treating carcinoma and various infectious diseases. Additionally, these NPs are beneficial for reducing organic and inorganic environmental pollutants. This review discusses about various methods to fabricate ZnFe2O4 NPs and their physicochemical properties. Further, their biomedical and environmental applications have also been explored comprehensively.

Studies on nanomaterial-based p-type semiconductor gas sensors

The development of various metal oxide semiconductor materials has resulted in better performance of the gas sensors in terms of selectivity, sensitivity, and response time. Different types of nanostructured materials, i.e., 2D materials, carbon nanotubes, and metal oxides, are used in the gas sensing applications. Generally, the metal oxide-based gas sensor operates at higher temperature to activate the adsorption process between the material surface and the target gas. The higher operating temperature of the gas sensor leads to more power consumption and produces defects in the grain boundary of metal oxide. To improve the selectivity and minimize the power consumption, nanoparticle-based p-type semiconductor materials are being developed. P-type metal oxide-based semiconductor materials have the ability to produce a hole accumulation layer which can chemisorb the oxygen molecules of higher concentration and these materials are not affected by humidity. The structure of p-type nanomaterial-based gas sensor depends upon the fabrication techniques which can affect the sensing properties of semiconductor materials. The hole accumulation layer is also known as conduction layer which is developed in the outer shell of p-type semiconductor material and the sensing mechanism is controlled by grain boundaries which is different from the n-type semiconductor material. This paper reviews the preparation methods, morphological analysis, and sensing mechanisms of nanomaterial-based p-type metal oxide-based gas sensors.

Synthesis of ZnO-CuO and ZnO-Co3O4 Materials with Three-Dimensionally Ordered Macroporous Structure and Its H2S Removal Performance at Low-Temperature

H2S is a common but hazardous impurity in syngas, biogas, or natural gas. For some advanced power generation technologies, such as integrated gasification combined cycle (IGCC), solid oxide fuel cells, H2S content needs to be reduced to an acceptable level. In this work, a series of highly porous Zn-Cu and Zn-Co composites with three-dimensionally ordered macropores (3DOM) structure were synthesized via the colloidal crystal template method and used to remove H2S at 150 °C and one atm. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption studies, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were carried out to analyze the fresh and spent adsorbents. The results show that all the adsorbents possess well-ordered macropores, a large surface area, and a highly dispersed active phase. The relative content of Zn and (Cu or Co) has a significant influence on the desulfurization performance of adsorbents. The addition of CuO significantly increases the sulfur capacity and 3DOM-Zn0.5Cu0.5 shows the largest sulfur capacity of all the adsorbents, reaching up to 102.5 mg/g. The multiple adsorption/regeneration cycles of 3DOM-Zn0.5Cu0.5 and 3DOM-Zn0.5Co0.5 indicate that the as-prepared adsorbents are stable, and the sulfur capacity can still exceed 65% of the fresh adsorbents after six cycles.