scholarly journals Photoreduction of a Pd-Doped Mesoporous TiO2 Photocatalyst for Hydrogen Production under Visible Light

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 74 ◽  
Author(s):  
Bianca Rusinque ◽  
Salvador Escobedo ◽  
Hugo de Lasa
Keyword(s):  
Hydrogen Production ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Morphological Characteristics ◽  
Production Performance ◽  
Bet Surface Area ◽  
Tio2 Photocatalyst ◽  
X Ray ◽  
Production Of Hydrogen

Photoreduction with visible light can enhance the photocatalytic activity of TiO2 for the production of hydrogen. In this article, we present a strategy to photoreduce a palladium-doped TiO2 photocatalyst by using near-UV light prior to its utilization. A sol-gel methodology was employed to prepare the photocatalysts with different metal loadings (0.25–5.00 wt% Pd). The structural and morphological characteristics of the synthesized Pd-TiO2 were analyzed by using X-ray Diffraction (XRD), BET Surface Area (SBET), TemperatureProgrammed Reduction (TPR), Chemisorption and X-ray Photoelectron Spectroscopy (XPS). Hydrogen was produced by water splitting under visible light irradiation using ethanol as an organic scavenger. Experiments were developed in the Photo-CREC Water-II (PCW-II) Reactor designed at the CREC-UWO (Chemical Reactor Engineering Centre). It was shown that the mesoporous 0.25 wt% Pd-TiO2 with 2.5 1eV band gap exhibits, under visible light, the best hydrogen production performance, with a 1.58% Quantum Yield being achieved.

scholarly journals Green hydrogen production by solar photocatalysis using Pt-TiO2 nanosheets with reactive facets

2021 ◽  
Vol 28 (2) ◽  
pp. 75-81
Author(s):  
Bin Wang ◽  
Daniel H C Wan ◽  
Altair T F Cheung ◽  
Denis Y C Leung ◽  
Xiao-Ying Lu ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Diffuse Reflectance Spectroscopy ◽  
Production Performance ◽  
Photocatalytic Hydrogen Production ◽  
X Ray ◽  
Transmission Electron ◽  
Tio2 Nanosheets ◽  
Production Of Hydrogen ◽  
Green Production ◽  
Renewable Hydrogen

Green production of hydrogen is essential for the development of a hydrogen economy. In this study, the photocatalytic water-splitting technology is developed to harness solar energy for production of renewable hydrogen. Pt-TiO2 nanosheets were fabricated by a facile hydrothermal method, followed by photo-reduction of Pt(acac)2 on B,F-codoped TiO2 with reactive facets. The as-prepared photocatalysts were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic hydrogen production performance was systematically investigated under UV-visible irradiation. The parametric results indicate that the TiO2 nanosheet structure, Pt loading and photocatalyst concentration have significant impacts on the photocatalytic hydrogen production. The highest hydrogen production rate obtained is 5,086 μmol h-1g-1.

Synthesis of Nitrogen and Sulfur Codoped TiO2 and its Better Efficient Degradation of Organophosphorus Pesticides

2011 ◽  
Vol 183-185 ◽  
pp. 1787-1790
Author(s):  
Guang Sheng Chen ◽  
Si Yao Guo ◽  
Feng Zhang ◽  
Shi Miao Dong ◽  
Song Han
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Degradation Rate ◽  
Uv Light ◽  
Organophosphorus Pesticides ◽  
Organophosphorus Pesticide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Efficiency

N, S codoped titania with high photocatalystic properties were prepared by hydrothermal method. The resulting materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy. N, S codoped titania displayed a better degradation rate of organophosphorus pesticide under visible light irradiation. The utility of N, S codoped TiO2 as a photocatalysis over undoped titania entirely, whether the requirement for visible-light functionality, even if at low efficiency, outweighs a modest drop in the efficiency of catalysis using UV light.

scholarly journals The Activation of Mg Powder Promoted by Chloride and Activation Mechanism

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1435
Author(s):  
Xiaoxuan Wang ◽  
Xiaoyan Guo ◽  
Lixiang Zhu ◽  
Shuo Wang ◽  
Meishuai Zou ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Ball Milling ◽  
Photoelectron Spectroscopy ◽  
Hydrogen Generation ◽  
Synergistic Effects ◽  
Milling Process ◽  
Production Performance ◽  
Activation Mechanism ◽  
X Ray ◽  
Highly Active

Magnesium has bright market prospects such as generating thrust for under water engines and hydrogen production. However, the passive oxide film on the surface of magnesium powder prevents the further reaction of magnesium with water at room temperature. In this paper, highly active magnesium-based materials were prepared via ball milling pure Mg with different chlorides (NiCl2, CoCl2, CuCl2, FeCl3). The activity of the as obtained powder was analyzed through Scanning Electron Microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), synchrotron X-ray tomography, Extended X-ray Absorption Fine Structure (EXAFS), etc. Among the various compositions, the Mg-6%CoCl2 composite exhibited the best hydrogen production performance with a hydrogen generation volume of 423 mL/(0.5 g) and a conversion yield of 96.6%. The related activation mechanism was thoroughly studied, showing that the addition of chloride during ball milling can effectively break the continuity of oxide films on Mg surfaces and introduces a large number of micro defects. In addition, the EXAFS and tomography data verified that metallic cobalt was generated during the ball milling process, subsequently forming a Mg-Co micro glance cell, and the Cl− in the system accelerates the corrosion of Mg. The active mechanism can be verified as synergistic effects of micro glance cell and as-generated surface microcracks.

scholarly journals Enhanced Photocurrent of the Ag Interfaced Topological Insulator Bi2Se3 under UV- and Visible-Light Radiations

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3353
Author(s):  
Chih-Chiang Wang ◽  
Pao-Tai Lin ◽  
Fuh-Sheng Shieu ◽  
Han-Chang Shih
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Visible Range ◽  
Zero Bias ◽  
X Ray ◽  
Topological Quantum ◽  
Conductive Surface ◽  
Narrow Bandgap

Bi2Se3 is a topological quantum material that is used in photodetectors, owing to its narrow bandgap, conductive surface, and insulating bulk. In this work, Ag@Bi2Se3 nanoplatelets were synthesized on Al2O3(100) substrates in a two-step process of thermal evaporation and magnetron sputtering. X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) revealed that all samples had the typical rhombohedral Bi2Se3. Field-emission scanning electron microscopy (FESEM)-energy dispersive x-ray spectroscopy (EDS), XPS, and HRTEM confirmed the presence of the precipitated Ag. The optical absorptance of Bi2Se3 nanoplatelets in UV-visible range decreased with the Ag contents. Results of photocurrent measurements under zero-bias conditions revealed that the deposited Ag affected photosensitivity. A total of 7.1 at.% Ag was associated with approximately 4.25 and 4.57 times higher photocurrents under UV and visible light, respectively, than 0 at.% Ag. The photocurrent in Bi2Se3 at 7.1 at.% Ag under visible light was 1.72-folds of that under UV light. This enhanced photocurrent is attributable to the narrow bandgap (~0.35 eV) of Bi2Se3 nanoplatelets, the Schottky field at the interface between Ag and Bi2Se3, the surface plasmon resonance that is caused by Ag, and the highly conductive surface that is formed from Ag and Bi2Se3. This work suggests that the appropriate Ag deposition enhances the photocurrent in, and increases the photosensitivity of, Bi2Se3 nanoplatelets under UV and visible light.

scholarly journals Exfoliated Molybdenum Disulfide Encapsulated in a Metal Organic Framework for Enhanced Photocatalytic Hydrogen Evolution

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 89 ◽  
Author(s):  
Ren Ren ◽  
Huilei Zhao ◽  
Xiaoyu Sui ◽  
Xiaoru Guo ◽  
Xingkang Huang ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Visible Light ◽  
Light Absorption ◽  
Photoelectron Spectroscopy ◽  
Metal Organic Framework ◽  
Visible Light Absorption ◽  
X Ray ◽  
Metal Organic ◽  
Direct Band ◽  
Bulk Mos2

An exfoliated MoS2 encapsulated into metal-organic frameworks (MOFs) was fabricated as a promising noble-metal-free photocatalyst for hydrogen production under visible light irradiation. The as-synthesized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) surface analysis. It is well known that bulk MoS2 is unsuitable for photocatalysis due to its inadequate reduction and oxidation capabilities. However, exfoliated MoS2 exhibits a direct band gap of 2.8 eV due to quantum confinement, which enables it to possess suitable band positions and retain a good visible-light absorption ability. As a result, it is considered to be an encouraging candidate for photocatalytic applications. Encapsulating exfoliated MoS2 into MOF demonstrates an improved visible light absorption ability compared to pure MOF, and the highest hydrogen production rate that the encapsulated exfoliated MoS2 could reach was 68.4 μmol h-1g-1, which was much higher than that of pure MOF. With a suitable band structure and improved light-harvesting ability, exfoliated MoS2@MOF could be a potential photocatalyst for hydrogen production.

scholarly journals Influence of the preparation method on the photocatalytic activity of Nd-modified TiO2

2018 ◽  
Vol 9 ◽  
pp. 447-459 ◽  
Author(s):  
Patrycja Parnicka ◽  
Paweł Mazierski ◽  
Tomasz Grzyb ◽  
Wojciech Lisowski ◽  
Ewa Kowalska ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Diffuse Reflectance Spectroscopy ◽  
Bet Surface Area ◽  
Luminescence Spectroscopy ◽  
X Ray ◽  
Gaseous Toluene

Nd-modified TiO2 photocatalysts have been obtained via hydrothermal (HT) and sol–hydrothermal (SHT) methods. The as-prepared samples were characterized by X-ray diffraction (XRD), BET surface area measurements, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), luminescence spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the synthesized samples was evaluated by the degradation of phenol in aqueous solution under irradiation with UV–vis (λ > 350 nm) and vis (λ > 420 nm) light, as well as by the degradation of gaseous toluene under irradiation with vis (λmax = 415 nm) light. It was found that Nd-modified TiO2 is an efficient photocatalyst for the degradation of phenol and toluene under visible light. XPS analysis revealed that the photocatalyst prepared via HT method contains a three-times higher amount of hydroxy groups at the surface layer and a two-times higher amount of surface defects than that obtained by the SHT method. The photocatalytic efficiency of phenol and toluene degradation under vis irradiation in the presence of 0.25% Nd-TiO2(HT) reached 0.62 and 3.36 μmol·dm−1·min−1, respectively. Photocatalytic activity tests in the presence of Nd-TiO2 and scavenger confirm that superoxide radicals were responsible for the visible light-induced degradation of the model pollutant in aqueous solution.

scholarly journals Zinc Oxide Nanoparticles from Waste Zn-C Battery via Thermal Route: Characterization and Properties

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 717 ◽  
Author(s):  
Rifat Farzana ◽  
Ravindra Rajarao ◽  
Pravas Behera ◽  
Kamrul Hassan ◽  
Veena Sahajwalla
Keyword(s):  
Electron Microscopy ◽  
Zno Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Inert Atmosphere ◽  
Bet Surface Area ◽  
Visible Range ◽  
Tem Analysis ◽  
Thermal Synthesis ◽  
X Ray

Disposable batteries are becoming the primary sources of powering day-to-day gadgets and consequently contributing to e-waste generation. The emerging e-waste worldwide is creating concern regarding environmental and health issues. Therefore, a sustainable recycling approach of spent batteries has become a critical focus. This study reports the detail characterization and properties of ZnO nanoparticles recovered from spent Zn-C batteries via a facile thermal synthesis route. ZnO nanoparticles are used in many applications including energy storage, gas sensors, optoelectronics, etc. due to the exceptional physical and optical properties. A thermal treatment at 900 °C under an inert atmosphere of argon was applied to synthesize ZnO nanoparticles from a spent Zn-C battery using a horizontal quartz tube furnace. X-ray diffraction (XRD), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of crystalline ZnO nanoparticles. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis confirmed that the size of synthesised ZnO particles were less than 50 nm and mainly composed of sphere shaped nanoparticles. Synthesized ZnO exhibited BET surface area of 9.2629 m2/g and showed absorption of light in the UV region. Excitation of ZnO by UV light showed photoluminescence in the visible range. This study will create an opportunity for potential applications of ZnO nanoparticles from spent batteries and will benefit the environment by reducing the volume of e-waste in landfills.

scholarly journals Enhancement of Hydrogen Productions by Accelerating Electron-Transfers of Sulfur Defects in the CuS@CuGaS2 Heterojunction Photocatalysts

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 41 ◽  
Author(s):  
Namgyu Son ◽  
Jun Heo ◽  
Young-Sang Youn ◽  
Youngsoo Kim ◽  
Jeong Do ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Production ◽  
Uv Light ◽  
Visible Region ◽  
Production Performance ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Transfers

CuS and CuGaS2 heterojunction catalysts were used to improve hydrogen production performance by photo splitting of methanol aqueous solution in the visible region in this study. CuGaS2, which is a chalcogenide structure, can form structural defects to promote separation of electrons and holes and improve visible light absorbing ability. The optimum catalytic activity of CuGaS2 was investigated by varying the heterojunction ratio of CuGaS2 with CuS. Physicochemical properties of CuS, CuGaS2 and CuS@CuGaS2 nanoparticles were confirmed by X-ray diffraction, ultraviolet visible spectroscopy, high-resolution transmission electron microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Compared with pure CuS, the hydrogen production performance of CuGaS2 doped with Ga dopant was improved by methanol photolysis, and the photoactivity of the heterogeneous CuS@CuGaS2 catalyst was increased remarkably. Moreover, the [email protected] catalyst produced 3250 μmol of hydrogen through photolysis of aqueous methanol solution under 10 h UV light irradiation. According to the intensity modulated photovoltage spectroscopy (IMVS) results, the high photoactivity of the CuS@CuGaS2 catalyst is attributed to the inhibition of recombination between electron-hole pairs, accelerating electron-transfer by acting as a trap site at the interface between CuGaS2 structural defects and the heterojunction.

scholarly journals Photodegradation of Microcystin-LR Using Visible Light-Activated C/N-co-Modified Mesoporous TiO2 Photocatalyst

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1027 ◽  
Author(s):  
Tamer Khedr ◽  
Said El-Sheikh ◽  
Adel Ismail ◽  
Ewa Kowalska ◽  
Detlef Bahnemann
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Tio2 Photocatalyst ◽  
X Ray

Microcystin-LR (MC-LR), a potent hepatotoxin produced by the cyanobacteria, is of increasing concern worldwide because of severe and persistent impacts on humans and animals by inhalation and consumption of contaminated waters and food. In this work, MC-LR was removed completely from aqueous solution using visible-light-active C/N-co-modified mesoporous anatase/brookite TiO2 photocatalyst. The co-modified TiO2 nanoparticles were synthesized by a one-pot hydrothermal process, and then calcined at different temperatures (300, 400, and 500 °C). All the obtained TiO2 powders were analyzed by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), specific surface area (SSA) measurements, ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) analysis. It was found that all samples contained mixed-phase TiO2 (anatase and brookite), and the content of brookite decreased with an increase in calcination temperature, as well as the specific surface area and the content of non-metal elements. The effects of initial pH value, the TiO2 content, and MC-LR concentration on the photocatalytic activity were also studied. It was found that the photocatalytic activity of the obtained TiO2 photocatalysts declined with increasing temperature. The complete degradation (100%) of MC-LR (10 mg L−1) was observed within 3 h, using as-synthesized co-modified TiO2 (0.4 g L−1) at pH 4 under visible light. Based on the obtained results, the mechanism of MC-LR degradation has been proposed.

scholarly journals Wastewater Contaminated with Hydrazine as Scavenger Agent for Hydrogen Production by Cu/Ti Nanostructures

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 74
Author(s):  
Mariana Hinojosa Reyes ◽  
Roberto Camposeco ◽  
Vicente Rodríguez González
Keyword(s):  
Hydrogen Production ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Diffuse Reflection Spectroscopy ◽  
Oh Groups ◽  
X Ray ◽  
Calcination Temperatures ◽  
Production Of Hydrogen ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

Cu/Ti photocatalysts were prepared by the sol-gel process with different copper loadings (1.0, 2.5, and 5.0 wt.%) and then thermally treated at several calcination temperatures from 400 to 600 °C. The materials were characterized by X-ray diffraction (XRD), N2 physisorption, Scanning Electronic Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS), Ultraviolet-visible-Diffuse Reflection Spectroscopy, Ultraviolet-visible spectroscopy as a function of the temperature, (Temperature Programmed Reduction) TPR-chemisorption, XPS (X-ray Photoelectron Spectroscopy) and OH determination through DRIFTS (Diffuse reflectance infrared Fourier transform spectroscopy). The Cu/Ti photocatalysts were evaluated for the photocatalytic production of hydrogen using hydrazine as scavenging agent. Moreover, a detailed study of the Cu1+/Cu2+ ratio and the corresponding formation of copper oxide was carried out to understand the correlation between the copper species and the photocatalytic activity. Simultaneously, the OH groups on the TiO2 surface also show insights into the behavior of these materials during the photocatalytic reaction. Despite the low hydrazine concentration (20 mM), the 1.0 (wt.%) Cu/Ti 500 photocatalyst enhanced the hydrogen production three and two times more than photolysis and bare TiO2, respectively. The 1.0 Cu/Ti 500 photocatalyst displayed outstanding stability for at least three continuous cycles of 8 h each, preserving the hydrogen production. The novel ability shown in this work represents an alternative to reduce the hydrazine residues in wastewater to transform it into a hydrogen-producing energy source and must be extended to other reductive pollutants found in wastewater.

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