Mn-doping-induced photocatalytic activity enhancement of ZnO nanorods prepared on glass substrates

Putri, Nur Ajrina; Fauzia, Vivi; Iwan, S.; Roza, Liszulfah; Umar, Akrajas Ali; Budi, Setia

doi:10.1016/j.apsusc.2017.12.246

Cited by 143 publications

(36 citation statements)

References 76 publications

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“…This evolution is presented in Figure 9 for the films deposited on the complex Pt/Ti/SiO 2 /Si substrate. Such dependence of the band gap energy is in good agreement with the literature data [33] and could be related to the defects induced by manganese doping in ZnO [34]. The transmission measurements were done by SE in the 340-800 nm wavelength ranges with a 10 nm step on SG films deposited on microscope glass substrate.…”

Section: Spectroscopic Ellipsometry (Se)supporting

confidence: 89%

Optical and Piezoelectric Properties of Mn-Doped ZnO Films Deposited by Sol-Gel and Hydrothermal Methods

Vladut

Mihaiu

Tenea

et al. 2019

Journal of Nanomaterials

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Nowadays, multifunctional materials are of high interest due to their ability to be used in different applications by controlling one or two parameters (e.g., morphology and/or dopant). Zinc oxide is an intensive-studied material because of its large usability. Recently, we have shown that the conduction, transparency, and charge carrier concentration of ZnO can be controlled by changing the dopants, leading to promising materials as transparent conductive oxide films. In this work, sol-gel (SG) and hydrothermal (HT) methods were used separately or in combination in order to obtain ZnO films doped with Mn (1, 2, and 5%) for possible application in transparent optoelectronics or as piezoelectric materials. The manganese (Mn) dopant in the form of anhydrous manganese acetate was used to obtain Mn-doped ZnO films. ZnO hydrothermal (HT) growth was made on a previously ZnO seed layer, formed by sol-gel method. The Mn-doped ZnO films were deposited on microscope glass and on Pt/Ti/SiO2/Si substrates. A comparative characterization of the films for their structure, morphology, and optical and piezoelectric properties was achieved. SG films exhibit equiaxed nanoparticles, with diameters around 50 nm, while the films prepared by HT show a homogeneous morphology consisting of uniform 1D nanorods, sized about 30 nm diameter and 200–300 nm length. XRD diffractograms evidenced the presence of zincite phase (wurtzite structure hexagonally close packed), with an improvement in crystallinity of the HT films (compared with SG ones), which present a stronger tendency to be oriented along (002) plane (c-axis) at 2% at Mn. Spectroscopic ellipsometry shows that the films obtained by SG are much thinner than the ones obtained by HT and that the refractive index is increasing with the percent of dopant. The band gap energy was found to decrease with the Mn doping level from 3.28 eV (undoped ZnO) to 3.10 eV (ZnO doped with 5 at% Mn) for the samples deposited on Pt/Ti/SiO2/Si. The maximum transmission is found for the undoped ZnO film and decreases with Mn concentration but remains over 78% in the visible range. From the piezoelectric tests, it was found that the d33 coefficient is much larger for the HT samples in comparison with the SG samples, especially for 2 and 5 at% Mn. The optical and piezoelectric results could be of interest for applications in optoelectronic or piezoelectric devices.

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Section: Spectroscopic Ellipsometry (Se)supporting

confidence: 89%

Optical and Piezoelectric Properties of Mn-Doped ZnO Films Deposited by Sol-Gel and Hydrothermal Methods

Vladut

Mihaiu

Tenea

et al. 2019

Journal of Nanomaterials

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“…Over the four cycles degradation efficiency remains the same which indicates the stability of prepared samples. Nur Ajrina et al reported that photodegradation efficiency for 7% Mn-doped ZnO nanorods was 76.75% under UV irradiation while in our case it was 82% for 4% Mn-doped ZnO nanoflowers under visible irradiation [43]. This clearly verifies that the 4% Mn-doped ZnO nanoflowers on glass substrate are reusable and more stable.…”

Section: Photocatalytic Activitysupporting

confidence: 80%

Development of oxygen vacancies and surface defects in Mn-doped ZnO nanoflowers for enhancing visible light photocatalytic activity

et al. 2020

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Pure and Mn-doped ZnO nanoflowers were successfully synthesized by the hydrothermal technique. Doping of Mn into ZnO lattice exhibits formation of oxygen vacancies and surface modifications into ZnO lattice was investigated by XPS spectra and AFM analysis. During the photocatalytic performance, vacancies create the trap centers for photogenerated electrons hence the electron-hole recombination is effectively inhibited. These formed oxygen vacancies along with enhanced surface area are due to Mn doping, resulted in effective photodegradation of methylene blue solution under solar light irradiation. The degradation efficiency for methylene blue dye exceeds 82% after 120 min under solar light irradiation, also the catalytic performance of Mn-doped ZnO nanoflowers retains even after 4 cycles.

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“…[ [95][96][97][98][99] According to literature, the UV emission corresponds to a near band edge (NBE) transition, which is related to excitonic recombination caused by shallow donors inside the ZnO band-gap. [96,[100][101][102] The visible emission has been attributed to the presence intrinsic and extrinsic defects, and also adsorbed molecules on the ZnO surface.…”

Section: Photoluminescence (Pl) Spectroscopymentioning

confidence: 99%

The role of counter-ions in crystal morphology, surface structure and photocatalytic activity of ZnO crystals grown onto a substrate

Catto

Ferrer

Lopes

et al. 2020

Applied Surface Science

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In this contribution, we present an experimental and theoretical investigation of the role of counter-ions in the crystal morphology, surface structure, and photocatalytic activity of hierarchical ZnO nanostructures. The effect of zinc precursor (nitrate, acetate and, sulfate) along the synthesis of ZnO nanostructures grown directly onto a substrate by means of a simple hydrothermal method was analyzed in detail. Scanning electron microscopy images showed a preferential growth of ZnO nanostructures along the caxis, with a slight reduction in the orientation depending on the choice of the Zn source. 2 Theoretical calculations based on Wulff theory allowed us a better understanding of the morphological changes and to directly relate the photocatalytic performance at the different exposed surfaces of the as-observed crystal shapes. Our results showed that photocatalytic activities in the discoloration of organic dyes became superior for hierarchical ZnO nanostructures obtained from zinc nitrate. This finding was explained by X-ray photoelectron and photoluminescence spectroscopies, which revealed that the presence of surface defects, as well as the attached counter-ions and the abundance of carboxylate groups and organic residuals on ZnO surfaces are determinant for enhanced photocatalytic performance.

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Mn-doping-induced photocatalytic activity enhancement of ZnO nanorods prepared on glass substrates

Cited by 143 publications

References 76 publications

Optical and Piezoelectric Properties of Mn-Doped ZnO Films Deposited by Sol-Gel and Hydrothermal Methods

Optical and Piezoelectric Properties of Mn-Doped ZnO Films Deposited by Sol-Gel and Hydrothermal Methods

Development of oxygen vacancies and surface defects in Mn-doped ZnO nanoflowers for enhancing visible light photocatalytic activity

The role of counter-ions in crystal morphology, surface structure and photocatalytic activity of ZnO crystals grown onto a substrate

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