Effects of Co Doping on the Growth and Photocatalytic Properties of ZnO Particles

Abstract

The present work reports on the synthesis of ZnO photocatalysts with different Co-doping levels via a facile one-step solution route. The structural and optical properties were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and UV-Vis diffuse reflectance spectra. The morphology of Co-doped ZnO depends on the reaction temperature and the amount of Co and counter-ions in the solution. Changes with the c-axis lattice constant and room temperature redshift show the replacement of Zn with Co ions without changing the wurtzite structure. Photocatalytic activities of Co-doped ZnO on the evolution of H2 and the degradation of methylene blue (MB) reduce with the doping of Co ions. As the close ionic radii of Co and Zn, the reducing photocatalytic activity is not due to the physical defects but the formation of deep bandgap energy levels. Photocurrent response experiments further prove the formation of the recombination centers. Mechanistic insights into Co-ZnO formation and performance regulation are essential for their structural adaptation for application in catalysis, energy storage, etc.

A Study on Doping and Compound of Zinc Oxide Photocatalysts

“…Lanqin Tang et al [ 38 ] prepared zinc oxide photocatalysts with different co-doping degrees by the one-step dissolution method. It was found that the morphology of co-doped zinc oxide depended on the reaction temperature and the content of cobalt in solution.…”

Photoresponsive Activity of the Zn0.94Er0.02Cr0.04O Compound with Hemisphere-like Structure Obtained by Co-Precipitation

“…Different studies proved that ZnO doped with transition metal ions presents a satisfactory photocatalytic response in recalcitrant compounds. Some of these studies included the addition of metals such as Co [ 21 ], Ag [ 22 ], Ni [ 23 ], Cu [ 24 ] and Mn [ 25 ]. The Cr insertion in the ZnO matrix is not a complicated process due to the proximity of the ionic radii of Cr 3+ (0.62 Å) and Zn 2+ (0.72 Å), and it can also be considered as an alternative to improve the photocatalytic response of ZnO.…”

Applications of Catalytic Nanomaterials in Energy and Environment

“…In recent years, great progress has been made in thermal catalysis, photocatalysis, and electrocatalysis for energy and environmental applications. In particular, pollutant degradation [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], green hydrogen production [ 8 ], indoor formaldehyde purification [ 9 ], oxygen reduction [ 10 ], and other fields [ 11 , 12 , 13 ] have ushered in major developmental opportunities and important original breakthroughs.…”

“…Improving the sunlight utilization efficiency and catalytic activity of photocatalytic nanomaterials constitutes the key problem restricting the large-scale application of photocatalytic technology. This Special Issue presents a detailed account of the internal mechanism whereby photocatalytic activity is enhanced via elemental doping [ 1 , 2 , 3 ], the construction of composite heterogeneous structures [ 4 , 5 , 6 , 10 ], the introduction of organic photosensitive materials [ 8 ], morphology control [ 9 ], and so on. These contributions provide various approaches to the design and establishment of efficient photocatalytic nanomaterials.…”