Metal oxides as photocatalysts

Khan, Mohammad Mansoob; Adil, Syed Farooq; Al‐Mayouf, Abdullah M.

doi:10.1016/j.jscs.2015.04.003

Cited by 508 publications

(213 citation statements)

References 21 publications

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“…The electronic structure of TiO 2 and ZnO, both belonging to the family of semiconducting metal oxides, determines their catalytic properties [31]. The semiconductors have a valence band (VB), which is filled with electrons, and an electron-free conduction band (CB).…”

Section: Reviewmentioning

confidence: 99%

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

2017

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Cancer has become a global problem. On all continents, a great number of people are diagnosed with this disease. In spite of the progress in medical care, cancer still ends fatal for a great number of the ill, either as a result of a late diagnosis or due to inefficiency of therapies. The majority of the tumors are resistant to drugs. Thus, the search for new, more effective therapy methods continues. Recently, nanotechnology has been attributed with big expectations in respect of the cancer fight. That interdisciplinary field of science creates nanomaterials (NMs) and nanoparticles (NPs) that can be applied, e.g., in nanomedicine. NMs and NPs are perceived as very promising in cancer therapy since they can perform as drug carriers, as well as photo- or sonosensitizers (compounds that generate the formation of reactive oxygen species as a result of either electromagnetic radiation excitation with an adequate wavelength or ultrasound activation, respectively). Consequently, two new treatment modalities, the photodynamic therapy (PDT) and the sonodynamic therapy (SDT) have been created. The attachment of ligands or antibodies to NMs or to NPs improve their selective distribution into the targeted organ or cell; hence, the therapy effectiveness can be improved. An important advantage of the targeted tumor treatment is lowering the cyto- and genotoxicity of active substance towards healthy cells. Therefore, both PDT and SDT constitute a valuable alternative to chemo- or radiotherapy. The vital role in cancer eradication is attributed to two inorganic sensitizers in their nanosized scale: titanium dioxide and zinc oxide.

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Section: Reviewmentioning

confidence: 99%

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

2017

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“…When these semiconductors absorb photon energy greater than their bandgap, the electrons from the valence band are excited to the conduction band and an electron-hole pair is created [37]. The electron-hole pair is a strong redox system [38], and in the presence of an absorbed compound in the photocatalyst surface, it can reduce and/or oxidize the compound [38][39][40]. As a result, the electrons will reduce oxygen on semiconductor surfaces, generating superoxide radicals and hydroperoxide radicals (•OHH) upon further reaction with H + .…”

Section: Introductionmentioning

confidence: 99%

Paper-Based Nanoplatforms for Multifunctional Applications

Matias

Nunes

Pimentel

et al. 2019

Journal of Nanomaterials

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In this work, zinc oxide (ZnO) and titanium dioxide (TiO 2 ) nanostructures were grown on different cellulose paper substrates, namely, Whatman, office, and commercial hospital papers, using a hydrothermal method assisted by microwave irradiation. Pure ZnO and TiO 2 nanostructures were synthesized; however, the growth of TiO 2 above ZnO was also investigated to produce a uniform heterostructure. Continuous ZnO nanorod arrays were grown on Whatman and hospital papers; however, on office paper, the formation of nanoplates originating nanoflower structures could be observed. TiO 2 nanoparticles homogeneously covered all the substrates, in some conditions forming uniform TiO 2 films. Structural characterization was carried out by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy. The optical characterization of all the materials was carried out. The produced materials were investigated for multifunctional applications, like photocatalyst agents, bacterial inactivators, and ultraviolet (UV) sensors. To evaluate the photocatalytic activity under UV and solar radiations, rhodamine B was the model-test contaminant indicator and the best photocatalytic activity was achieved with Whatman paper. Hospital paper with TiO 2 nanoparticles showed significant antibacterial properties against Staphylococcus aureus. ZnO-based UV sensors demonstrated a responsivity of 0.61 μA W -1 .

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“…Most studies in the field of photocatalysis are focusedo nt he synthesis,c haracterization of properties,a nd testing of nanomaterials able to catalyze the degradation of pollutants, [32][33][34][35][36][37][38][39][40][41] water splitting, [42][43][44][45][46][47][48][49] or the photoreforming of organic compounds. [50][51][52][53] Some materials used for these applications are transition metal oxides, [54][55][56][57][58][59][60][61][62][63][64] oxynitrides, [65][66][67][68][69][70][71][72][73][74][75] oxysulfides, [76][77][78][79][80]…”

Section: Factors Affecting Photocatalytic Hydrogen Generationmentioning

confidence: 99%

Operational Conditions Affecting Hydrogen Production by the Photoreforming of Organic Compounds using Titania Nanoparticles with Gold

et al. 2018

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Several factors affect photocatalytic hydrogen productivity from the photoreforming of organic compounds, which makes it difficult to optimize operational conditions in photoreactors. To prioritize these factors, we focused on the quantification of the effect of five of them on hydrogen production. Photocatalytic experiments were performed on 67 mL batch photoreactors under UV‐LED lamps (λ=375 nm) using a suspension of TiO2–Au nanoparticles synthesized by a sol–gel approach. The analyzed factors were: (A) presence of Au as a cocatalyst, (B) type of alcohol as the electron donor, (C) intensity of UV light, (D) electron donor concentration, and (E) nanoparticle concentration. A main and interaction effects analysis is presented with reduced fixed effect models for three responses: total hydrogen generation, catalyst productivity, and electron donor productivity. The presence of Au as a cocatalyst (A), the intensity of UV light (C), and their interaction (AC) were the factors with the highest effect. The best configuration allowed us to reach a catalyst productivity of 2925 μmolnormalH2 g−1 h−1.

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Metal oxides as photocatalysts

Cited by 508 publications

References 21 publications

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

Paper-Based Nanoplatforms for Multifunctional Applications

Operational Conditions Affecting Hydrogen Production by the Photoreforming of Organic Compounds using Titania Nanoparticles with Gold

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