The Applications of Morphology Controlled ZnO in Catalysis

Abstract

Zinc oxide (ZnO), with the unique chemical and physical properties of high chemical stability, broad radiation absorption range, high electrochemical coupling coefficient, and high photo-stability, is an attractive multifunctional material which has promoted great interest in many fields. What is more, its properties can be tuned by controllable synthesized morphologies. Therefore, after the success of the abundant morphology controllable synthesis, both the morphology-dependent ZnO properties and their related applications have been extensively investigated. This review concentrates on the properties of morphology-dependent ZnO and their applications in catalysis, mainly involved reactions on green energy and environmental issues, such as CO 2 hydrogenation to fuels, methanol steam reforming to generate H 2 , bio-diesel production, pollutant photo-degradation, etc. The impressive catalytic properties of ZnO are associated with morphology tuned specific microstructures, defects or abilities of electron transportation, etc. The main morphology-dependent promotion mechanisms are discussed and summarized.

Influence of Mg Doping on ZnO Nanoparticles for Enhanced Photocatalytic Evaluation and Antibacterial Analysis

“…It seems that Mg-doped ZnO NPs act similar to electron sink, which consequently can enhance significantly the separation of the photo-generated electron−hole pairs and inhibit their recombination resulting in improved photocatalytic activity [58]. …”

Process Intensification of Alkynol Semihydrogenation in a Tube Reactor Coated with a Pd/ZnO Catalyst

“…The smaller Pd nanoparticles are expected to result in broad peaks and the correspondingly low signal from the particles [24]. The Pd nanoparticles of comparable dimensions (4-6 nm) were also not observed over the ZnO support in powder X-ray The nitrogen physisorption study demonstrated low surface area of the support of 0.5 m 2 g −1 , which is typical for crystalline ZnO materials [42,43]. The powder X-ray diffraction study showed mainly the presence of hexagonal wurtzite crystals with the average diameter of 60 nm based on the Scherrer equation estimation for the most intensive peak at 2θ = 37.4 • (Figure 2).…”

“…The macroporous structure formed by such needle-shaped crystals of the coating is greatly beneficial for the internal mass transfer as it provides high diffusion coefficients when compared to microporous materials. The nitrogen physisorption study demonstrated low surface area of the support of 0.5 m 2 g −1 , which is typical for crystalline ZnO materials [42,43]. The powder X-ray diffraction study showed mainly the presence of hexagonal wurtzite crystals with the average diameter of 60 nm based on the Scherrer equation estimation for the most intensive peak at 2θ = 37.4° (Figure 2).…”

Tuning the Morphology of ZnO Nanostructures with the Ultrasonic Spray Pyrolysis Process

“…ZnO in a nanosized form is an indispensable candidate for electronic, optical, and gas sensors, as well as in catalysis applications, owing to its band gap value of 3.37 eV, large exciton binding energy of 60 meV and high electron mobility [1][2][3][4][5]. In the last decade, ZnO with various morphologies, including flower-like [6,7], nanodisc [1], nanobelt [8], and nanotube [9], targeting various application areas, have been investigated using different synthesis methods, e.g., sol-gel [10], hydrothermal [11], the microwave-assisted method [12] and spray pyrolysis [13].…”