Co doped ZnO nanowires as visible light photocatalysts

Šutka, Andris; Käämbre, Tanel; Pärna, Rainer; Juhņeviča, Inna; Maiorov, Mihael; Joost, Urmas; Kisand, Vambola

doi:10.1016/j.solidstatesciences.2016.04.008

Cited by 100 publications

(52 citation statements)

References 67 publications

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“…The visible absorption for Co:ZnO is similar to the major absorption peaks for tetrahedral Co 2+ molecular ions (e.g., CoCl4 2− peaks at 633, 668, 695 nm) [41,42]. Reports on Co-doped ZnO nanowires show visible absorption bands near 600 nm in good agreement with the data shown in Figure 6 [11]. In contrast, the Ni:ZnO materials show low broad absorption across the visible region (consistent with their gray color) and the three concentrations of Ni shift the band gap only slightly from the bulk ZZ-ZnO value.…”

Section: Templated Zno Characterizationsupporting

confidence: 81%

“…Thus, a 10% doping target would create a random distribution of ~1 metal dopant atom for every 10 zinc atoms in the tetrahedral sites of the wurtzite ZnO structure. In the case of Ni and Co doped ZnO, both atoms are known to substitute to high levels of nearly 20% without disruption of the wurtzite ZnO structure; these lattice substitutions are aided by similarities in M 2+ cation radii [11,14,16]. To gain a better understanding of the surface-sensitive structural properties of these leaftemplated ZnO materials, X-ray photoelectron spectroscopy (XPS) was performed on ground powders.…”

Section: Templated Zno Characterizationmentioning

confidence: 99%

“…In contrast, the Ni:ZnO materials show low broad absorption across the visible region (consistent with their gray color) and the three concentrations of Ni shift the band gap only slightly from the bulk ZZ-ZnO value. The M n+ ions doped into ZnO are proposed to introduce d orbital levels within the ZnO band gap (between VB and CB) that can lead to lower energy absorption of VB electrons into the dopant levels [11][12][13]. Scanning electron microscopy was performed to examine the extent that the internal ZZ leaf structure is successfully templated in the ZnO products (versus just an exterior replication as shown in Figure 1).…”

Section: Templated Zno Characterizationmentioning

confidence: 99%

“…Transition-metals with unpaired electrons can lead to partly filled orbitals inside the ZnO intrinsic band gap region and affect both optical and magnetic properties. A range of metals including Co, Ni, Fe, Mn, and Sn have been doped into the wurtzite ZnO structure for nanoscale optical properties and photocatalytic reactions [7][8][9][10][11][12][13][14]. The hexagonal ZnO structure has shown good ability to incorporate significant amounts of transition-metal dopants (1-10%) that substitute for Zn 2+ in the wurtzite structure and may provide useful photocatalytic tunability that is not as easily available in TiO 2 [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Metal dopant orbitals generally lie inside the ZnO band gap and may enhance visible light absorption and can aid in producing reactive oxygen species from photogenerated electrons [2,10,12,16]. Reducing particle sizes to nanoscale dimensions has been shown to increase accessible surface areas than can improve photocatalytic activity [8,11,15,16,19].…”

Section: Introductionmentioning

confidence: 99%

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Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

2018

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With an increased focus on light energy to facilitate catalytic processes, photocatalysts have been intensively studied for a wide range of energy and environmental applications. In this report, we describe the use of chemically dehydrated leaves as sacrificial foam-like templates for the growth of monolithic macrostructured semiconducting zinc oxide and nickel or cobalt doped zinc oxide materials. The composition and structure of these templated zinc oxides were characterized using X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Optical properties were examined using solid-state UV–vis diffuse reflectance spectroscopy. The metal-doped ZnO materials have enhanced visible absorption and lower band gaps as compared to ZnO. The botanically templated ZnO materials retain the macroscopic cellular form of the leaf template with fused nanoparticle walls. Their UV photocatalytic oxidative abilities were investigated using methylene blue dye degradation in air. The leaf templated zinc oxides degrade ~85% of methylene blue dye with 30 min of UV illumination. Nickel and cobalt doped zinc oxides showed varying degrees of decreased UV and visible light photocatalytic activity, possibly due to metal-mediated charge recombination. The mild chemical dehydration process here allows complex soft botanical structures to be easily utilized for templating materials.

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Section: Templated Zno Characterizationsupporting

confidence: 81%

Section: Templated Zno Characterizationmentioning

confidence: 99%

Section: Templated Zno Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

2018

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Photocatalytic Performance of Zinc Oxide and Metal‐Doped Zinc Oxide for Various Organic Pollutants

et al. 2023

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Zinc oxide (ZnO) has a high photocatalytic potential to decompose volatile organic pollutants into CO2 and H2O which depend on their physical properties, such as particle shape and size, band gap, type of dopant, and optical and structural properties. Using 93 references listed in this review, the relationship between metal dopant and synthesis methods to the efficiency of ZnO and composite ZnO‐metal in degrading pollutants for photocatalyst applications is studied. The basic principles of the photocatalyst process is described when the electrons at the valence band of ZnO get the energy from solar spectrum, generate the charge (electron and hole), and then continue to react with superoxide and water, resulting in radical atoms which break the bonds of organic pollutants. Rare earth dopants have the highest efficiency up to 100 % at 15 min irradiation. Conclusions and future prospects of ZnO and metal‐doped ZnO are also discussed. Perspectives and challenges of the future development of ZnO‐based photocatalysts are evaluated.

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Advances in Rare Earth‐Doped ZnO Photocatalysts: Enhancing Photogenerated Electron‐Hole Pairs for Radical Atom Generation

Hasanah,

Ikbal,

Tahir

2024

ChemBioEng Reviews

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Zinc oxide (ZnO) is a promising material with a diverse range of applications, spanning gas sensing, photonics, photovoltaics, energy conversion, water splitting, photocatalysis, and transparent trapping. However, ZnO limited responsiveness to visible light affected to low photogenerated electron‐hole pairs (charge), low quantum efficiency, and high recombination of charge. In this review, we are addressing innovative strategies, including incorporation rare earth elements as a trap of electron to reduce recombination charge via ZnO doping from analysis 118 referenced sources. We found that hydrothermal shows very good methods for boosting efficiency up to 100 % within 60‐min. We found that for rare‐earth metals La and Ce as a doping show highest efficiency up to 100 % within 120 min irradiations, means that efficient as a trap for reducing recombination of charge. The potential of rare earth doped ZnO will enhance photogenerated electron‐hole pairs, catalyzing the generation of radical atoms via oxidation and reduction reactions. This review encapsulates the most current findings, it serves as a valuable resource for scholars seeking to advance their understanding of rare earth doped ZnO photocatalysts and developing innovative photocatalytic technologies.

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Co doped ZnO nanowires as visible light photocatalysts

Cited by 100 publications

References 67 publications

Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

Photocatalytic Performance of Zinc Oxide and Metal‐Doped Zinc Oxide for Various Organic Pollutants

Advances in Rare Earth‐Doped ZnO Photocatalysts: Enhancing Photogenerated Electron‐Hole Pairs for Radical Atom Generation

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