Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials

Kamarulzaman, Norlıda; Kasim, Muhd Firdaus; Rusdi, Roshidah

doi:10.1186/s11671-015-1034-9

Cited by 315 publications

(97 citation statements)

References 25 publications

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“…Therefore, the results indicate that the production of H 2 may not take place along a conventional water-splitting process. The data for H 2 production agree quite well with the results reported by other researchers 18,58 . Figure 7A shows the time-dependent photacatalytic H 2 generation through water splitting obtained from 0.5Ni-Si/MgO and 0.7Ni-Si/MgO samples.…”

Section: Resultssupporting

confidence: 91%

“…Here, the optical band gap energies of 0.5Ni-Si/MgO and 0.7Ni-Si/MgO were calculated from Tauc plots according to the relationship αhυ = C(hυ − E g ) 2 or (αhυ) 2 = C ′ (hυ − E g ), where α is the coefficient of absorption, hυ is the constant and E g is the band gap energy 58 , respectively. The evaluation of absorption coefficient was determined by α = Kln(R max -R min /R-R min ), where, maximum reflectance is the R max and the minimum reflectance is R min 58 . The estimation of band gap was performed by the plot (αhυ) 2 versus photon energy (hυ) and bandgap values for the 0.5Ni-Si/MgO and 0.7Ni-Si/MgO measured by the curve fitting were 2.48 eV and 2.58 eV respectively, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Ultrathin Assembles of Porous Array for Enhanced H2 Evolution

Islam¹,

Teo

Awual

et al. 2020

Sci Rep

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Since the complexity of photocatalyst synthesis process and high cost of noble cocatalyst leftovers a major hurdle to producing hydrogen (H 2 ) from water, a noble metal-free Ni-Si/MgO photocatalyst was realized for the first time to generate H 2 effectively under illumination with visible light. The catalyst was produced by means of simple one-pot solid reaction using self-designed metal reactor. The physiochemical properties of photocatalyst were identified by XRD, FESEM, HRTEM, EDX, UVvisible, XPS, GC and PL. The photocatalytic activities of Ni-Si/MgO photocatalyst at different nickel concentrations were evaluated without adjusting pH, applied voltage, sacrificial agent or electron donor. The ultrathin-nanosheet with hierarchically porous structure of catalyst was found to exhibit higher photocatalytic H 2 production than hexagonal nanorods structured catalyst, which suggests that the randomly branched nanosheets are more active surface to increase the light-harvesting efficiency due to its short electron diffusion path. The catalyst exhibited remarkable performance reaching up to 714 µmolh −1 which is higher among the predominant semiconductor catalyst. The results demonstrated that the photocatalytic reaction irradiated under visible light illumination through the production of hydrogen and hydroxyl radicals on metals. The outcome indicates an important step forward one-pot facile approach to prepare noble ultrathin photocatalyst for hydrogen production from water.Why do we need to promote hydrogen energy? The scientist lays out about four main reasons-energy-saving, minimal ecological impacts, energy security and industrial competitiveness. Industrially, fossil-fuel based hydrogen production process emits greenhouse gas to the environment 1 . The use of solar energy to produce hydrogen from water could accelerate the development of high-impact breakthrough clean energy technologies. By developing an optimal photocatalyst, scientists are searching for the ways of improving clean energy (H 2 ) production from water without producing greenhouse gases or having many adverse effects on the atmosphere.A variety of titanium dioxide (TiO 2 ) phases and nanostructures have been studied extensively for photocatalytic hydrogen production because of its earth-abundance, non-toxicity as well as thermal and chemical stability 1,2 . However, photoirradiated electron recombination and wide band gap of bare TiO 2 remain challenge on efficient hydrogen production. Much work has been directed towards the adaptation of noble Pd, Au metals on the TiO 2 metals 3-5 or through the use of sacrificial reagents 6 . Noble co-catalyst could serve as electron sinks to isolate the photogenerated electron-holes 3 . Moreover, noble metals assist to boost the reaction process by lowering over-potential for proton deduction 4 . Unfortunately, the state-of-the-art co-catalysts are still noble metals (e.g. Pt, Au, Pd) or their oxides that are rare and expensive. As a consequence, the discovery of robust, low-cost and earth-abundant co-catalyst...

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Ultrathin Assembles of Porous Array for Enhanced H2 Evolution

Islam¹,

Teo

Awual

et al. 2020

Sci Rep

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“…A band gap narrowing was exhibited, it was found to be 2.74 eV. The observed difference between the calculated band gap and the reported values [18] arises from embedding of the ZnO nanoparticles into the interstitial positions of the silicate matrix [19].…”

Section: Energy Band Gapmentioning

confidence: 68%

Remediation of methyl green dye from aqueous solution via adsorption and degradation using silica gel modified with hydrated zinc oxide catalyst

Mahmoud¹,

El-Moselhy²,

Alkhaldi³

2019

Desalination and Water Treatment

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a b s t r a c tThe modification of silica via incorporation of hydrated zinc oxide (HZnO) with different loadings was achieved using wet precipitation technique. After drying at room temperature, the obtained samples calcined at 105°C and characterized using X-ray powder diffractometer, scanning electron microscopy, electron diffraction X-ray, transmission electron microscopy, Fourier transform infrared spectroscopy and BET. The data of characterizations indicated the well-distributed HZnO particles inside the silicate matrix with average particle size were lower than the detection limit of some characterization instruments. Furthermore, the modification with HZnO led to a noticeable decrease in BET surface area and the energy band gap due to the occupation of ZnO for interstitial positions inside the silicate matrix. The modified samples were successfully utilized in the adsorption and photocatalytic degradation of Methyl green dye as one of the cationic hazardous organic pollutants. The adsorption capacity of the sorbent catalyst was found to be 24.91 mg g -1 , while complete degradation of the (2 × 10 -4 mol L -1 ) dye was fulfilled in no more than 16 min. The influence of different experimental parameters as pH, temperature, concentration of the dye and dose of the catalyst was examined. The results obtained indicate that both adsorption and degradation of MG were a pH, dose and temperature dependent. The easiness of regeneration of the exhausted catalyst and its successive reuse confirmed remarkable economic efficiency.

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“…Other attempts to narrow the band gap of ZnO include doping with metal impurities such as Cu and Mn [72]. The impurities incorporated into the semiconductor can be located at the surface (inhomogeneous doping), or dispersed throughout the electrode material as a solid solution (homogeneous doping).…”

Section: Modifications Of Zno For Enhanced Photocatalytic Water Oxidamentioning

confidence: 99%

Photocatalytic Water Oxidation on ZnO: A Review

2017

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Abstract:The investigation of the water oxidation mechanism on photocatalytic semiconductor surfaces has gained much attention for its potential to unlock the technological limitations of producing H 2 from carbon-free sources, i.e., H 2 O. This review seeks to highlight the available scientific and fundamental understanding towards the water oxidation mechanism on ZnO surfaces, as well as present a summary on the modification strategies carried out to increase the photocatalytic response of ZnO.

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Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials

Cited by 315 publications

References 25 publications

Ultrathin Assembles of Porous Array for Enhanced H2 Evolution

Ultrathin Assembles of Porous Array for Enhanced H2 Evolution

Remediation of methyl green dye from aqueous solution via adsorption and degradation using silica gel modified with hydrated zinc oxide catalyst

Photocatalytic Water Oxidation on ZnO: A Review

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