A vertically grown hematite nanosheet film modified with Ag nanoparticles (NPs) and Co–Pi cocatalyst exhibits a remarkably high photocurrent density of 4.68 mA cm−2 at 1.23 V versus RHE. The Ag NPs ...leads to significantly improved light harvesting and better charge transfer, while the Co–Pi facilitates a highly stable oxygen evolution process. This photoelectrode design provides more efficient photoelectrochemical systems for solar‐energy conversion.
Photocatalysis has attracted much attention in recent years due to its potential in solving energy and environmental issues. Even though numerous achievements have been made, the photocatalytic ...systems developed to date are still far from practical applications due to the low efficiency and poor durability. Efficient light absorption and charge separation are two of the key factors for the exploration of high performance photocatalytic systems, which is generally difficult to be obtained in a single photocata- lyst. The combination of various materials to form heterojunctions provides an effective way to better harvest solar energy and to facilitate charge separation and transfer, thus enhancing the photocatalytic activity and stability. This review concisely summarizes the recent development of visible light respon- sive heterojunctions, including the preparation and performances of semiconductor/semiconductor junctions, semiconductor/cocatalyst junctions, semiconductor/metal junctions, semiconductor/non- metal junctions, and surface heterojunctions, and their mechanism for enhanced light harvesting and charge separation/transfer.
Pd-based catalysts supported on high-surface-area carbon are widely used in formic acid fuel cells. The composition, structure, and support can be modified to maximize the capabilities of Pd-based ...catalysts in terms of catalytic activity, durability, and cost. Various studies have investigated tuning the properties of Pd-based catalysts by alloying Pd with other metals. In this study, Cr, Ni, Cu, and Zn were incorporated into Pd-based catalysts. First, the effects of mole ratios were studied between Pd and the metals. The Pd
n
Ni ratios on a reduced graphene oxide support (Pd
n
Ni/rGO) were prepared using the one-pot method without the use of any surfactants. All obtained rGO-supported Pd
n
Ni catalysts (
n
= 1, 2, 4, with diameter of 5 nm) were used for the electrocatalytic oxidation of formic acid. The electro-oxidation measurements revealed that the Pd
n
Ni/rGO samples had superior electrocatalytic performance both in current densities and stabilities for formic acid oxidation (FAO) compared to Pd/rGO. Furthermore, Pd
4
Ni/rGO had greater electrocatalytic activity than the other Pd
n
Ni/rGO samples. In addition, with the same mole ratio of metals, Pd
4
Cr/rGO had higher efficiency toward FAO than the other series in the order: Pd
4
Cr/rGO > Pd
4
Ni/rGO > Pd
4
Cu/rGO > Pd
4
Zn/rGO.
WO3 nanoplate arrays with (002) oriented facets grown on fluorine doped SnO2 (FTO) glass substrates are tailored by tuning the precursor solution via a facile hydrothermal method. A 2-step ...hydrothermal method leads to the preferential growth of WO3 film with enriched (002) facets, which exhibits extraordinary photoelectrochemical (PEC) performance with a remarkable photocurrent density of 3.7mAcm–2 at 1.23V vs. revisable hydrogen electrode (RHE) under AM 1.5G illumination without the use of any cocatalyst, corresponding to ~93% of the theoretical photocurrent of WO3. Density functional theory (DFT) calculations together with experimental studies reveal that the enhanced photocatalytic activity and better photo-stability of the WO3 films are attributed to the synergistic effect of highly reactive (002) facet and nanoplate structure which facilitates the photo–induced charge carrier separation and suppresses the formation of peroxo-species. Without the use of oxygen evolution cocatalysts, the excellent PEC performance, demonstrated in this work, by simply tuning crystal facets and nanostructure of pristine WO3 films may open up new opportunities in designing high performance photoanodes for PEC water splitting.
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•WO3 nanoplate arrays with enriched (200) and (002) facets were prepared.•A remarkably high photocurrent density of 3.7mAcm–2 at 1.23V vs. RHE under AM 1.5G illumination was achieved.•Synergistic crystal facet engineering and structural control are critical for designing efficient PEC water splitting system.
Engineering crystals of titanium dioxide (TiO
2
) to expose the most reactive facet has been proved to significantly improve its photocatalytic performance. While most TiO
2
with facets reported in ...the past was in a particle form, herein we directly grow TiO
2
with arbitrarily tunable facets onto a transparent conductive substrate. This could reduce interparticle boundaries, and thus suppress charge recombination and facilitate more efficient charge transport compared to particle-assembled films. Combined systematic experimental and theoretical (density functional theory, DFT) studies reveal that fluoride ions (F
−
) and protons (H
+
) could play a synergistic role in controlling TiO
2
crystals in the way that F
−
ions change the crystal phase of TiO
2
to anatase with low-index facets, while H
+
ions increase the {001}/{101} ratio. Moreover, the reductive and oxidative sites of facets are clearly elucidated by selective photodeposition of a noble metal and metal oxide. Different photocatalytic tests manifested that the {001} facet, which is conventionally believed to be the most reactive facet, does not always show the highest performance. On the other hand, the facets' reactivity appeared to depend on the types of reactions (reduction or oxidation) and the co-existing synergy of facets. These findings would provide a clear understanding of the true factors controlling facets, and the true order of reactivity of each facet that has remained controversial, and pave a way to improve both the efficiency and selectivity of TiO
2
in a wide variety of photocatalytic applications in the future.
The ambient air concentrations of PM10 were observed in Bangkok and its vicinity areas including Nonthaburi and Nakhon Pathom, Thailand. The selected study areas are located near heavy-traffic roads ...with a high concentration of traffic-related air pollution. The ambient air samples were collected in the winter season (October 2019 to February 2020). The highest average level of PM10 was found in Nonthaburi (66.63 µg/m3), followed by Bangkok (56.79 µg/m3) and Nakhon Pathom (40.18 µg/m3), respectively. The morphology of these particles is typically spherical and irregular shape particles. At the sampling site in Bangkok, these particles are primarily composed of C, O, and Si, and a certain amount of metals such as Fe, Cu, and Cr. Some trace amount of other elements such as Ca, Na, and S are present in minor concentration. The particles collected from Nakhon Pathom and Nonthaburi sampling sites contain the main abundant elements C, O, and Si, followed by Cu, Cr, S, Fe, Ca, and Na, respectively. These particles are an agglomeration of carbon particles resulting from the incomplete combustion of organic matter. Their origin may be associated with road dust, vehicle emission, and the erosion of building products. It can be noted that the levels and characteristics of PM10 are key factors in understanding the behavior of the particles in not only atmospheric visibility but also human health risks.
Herein, we report the influence of iron(III) on the crystallization of chromium(III) terephthalate metal–organic framework. The selective phase formation of polymorphs MIL-101 and MIL-88B can be ...systematically controlled by varying the concentration of metal-cationic competitor, iron(III). The addition of iron(III) affects not only the selective phase formation but also the morphology and crystallinity of chromium(III) terephthalate MOF. This investigation clearly indicates the crystal growth tailoring of polymorphic MOFs by means of the second metal ionic competitor.
ZnO and Aluminum doped ZnO nanoparticles (Al/ZnO NPs) were successfully synthesized by the sol-gel method. Together with the effect of calcination temperatures (200, 300 and 400 °C) and Al dosage ...(1%, 3%, 5% and 10%) on structural, morphological and optical properties of Al/ZnO NPs, their photocatalytic degradation of methyl orange (MO) dye was investigated. The calcination temperatures at 200, 300 and 400 °C in forming structure of ZnO NPs led to spherical nanoparticle, nanorod and nanoflake structures with a well-crystalline hexagonal wurtzite, respectively. The ZnO NPs calcined at 200 °C exhibited the highest specific surface area and light absorption property, leading to the MO removal efficiency of 80% after 4 h under the Ultraviolet (UV) light irradiation. The MO removal efficiency was approximately two times higher than the nanoparticles calcined at 400 °C. Furthermore, the 5% Al/ZnO NPs exhibited superior MO removal efficiency of 99% in only 40 min which was approximately 20 times enhancement in photocatalytic activity compared to pristine ZnO under the visible light irradiation. This high degradation performance was attributed to the extended light absorption, narrowed band gap and effective suppression of electron-hole recombination through an addition of Al metal.
Three-dimensional hierarchical mesoporous structures of titanium dioxide (3D-HPT) were synthesized by self-assembly emulsion polymerization. Polymethyl methacrylate (PMMA) and pluronic 123 (P123) ...were used as the soft templates and co-templates for assisting the formation of hierarchical 3D porous structures. The TiO2 crystal structure, morphology, and Remazol red dye degradation were investigated. The 3D-HPT and normal three-dimensional titanium dioxide (3D-T) presented the good connection of the nanoparticle-linked honeycomb within the form of anatase. The 3D-HPT structure showed greatly enhanced adsorption of Remazol dye, and facilitated the efficient photocatalytic breakdown of the dye. Surprisingly, 3D-HPT can adsorb approximately 40% of 24 ppm Remazol dye in the dark, which is superior to 3D-T and the commercial anatase at the same condition (approx. 5%). Moreover, 3D-HPT can completely decolorize Remazol dye within just 20 min, which is more than three folds faster than the commercial anatase, making it one of the most active photocatalysts that have been reported for degradation of Remazol dye. The superior photocatalytic performance is attributed to the higher specific surface area, amplified light-harvesting efficiency, and enhanced adsorption capacity into the hierarchical 3D inverse opal structure compared to the commercial anatase TiO2.
In this research, we introduce a facile synthesis of the superhydrophobic natural rubber latex foam (NRLF), sponge-NRLF materials with a high oil-sorption capacity. The superhydrophobic sponge-NRLF ...was prepared by decorating the halloysite nanotubes (HNTS), which are chemically modified by n-hexadecyltrimethoxysilane (HDTMS) on the surface. The effects of HDTMS@HNTs loading and vulcanization systems towards the superhydrophobic and superhydrophilic properties of the NRLF were investigated. It was found that NRLF vulcanized by conventional vulcanization system (CV) and coated with 6 wt% HDTMS@HNTs showed favorable oil/water selectivity with excellent water repellence with a contact angle of 151°. The modified NRLF showed excellent performance toward gasoline 95 with high sorption capacity, achieving up to 10 times of its own weight for a wide range of oils. Oil sorption capacity tended to decline with respect to increasing HDTMS@HNTs content and oil viscosity due to the reduced porosity and surface area of the modified NRLF. Interestingly, the modified NRLF exhibited excellent durability, as the sorption efficiency remained unchanged after 10 cycles. Moreover, their fire retardant was also improved.
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•Facile preparation of superhydrophobic and superoleophiclic natural rubber latex foam.•Natural rubber latex foam coated by hexadecyltrimethoxysilane modified halloysite nanotube.•Oil adsorption capacity and oil-water selectivity of modified natural rubber latex foam.
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