The Experts below are selected from a list of 28290 Experts worldwide ranked by ideXlab platform
Wei-de Zhang - One of the best experts on this subject based on the ideXlab platform.
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enhancing visible light photocatalytic activity of nitrogen deficient g c3n4 via Thermal polymerization of acetic acid treated melamine
Journal of Colloid and Interface Science, 2017Co-Authors: Wei-de ZhangAbstract:Nitrogen-deficient graphitic carbon nitride (CN-HAc) was synthesized by Thermal Condensation of acetic acid-treated melamine as a precursor. The nitrogen vacancies play a remarkable role on controlling the electronic structure of g-C3N4, such as extending the optical absorption and enhancing the separation efficiency of photogenerated charge carriers, resulting in the improvement of photocatalytic activity. The photocatalytic activity of the catalysts was evaluated by splitting water and degradation of rhodamine B (RhB) under visible light irradiation (λ>420nm). The average H2 evolution rate on CN-HAc is 24μmolh-1, which is about 5 times of that on pristine g-C3N4. Meanwhile, CN-HAc exhibits superior photocatalytic mineralization of RhB. The possible formation mechanism of nitrogen-deficient in the framework of g-C3N4 is proposed.
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porous graphitic carbon nitride derived from melamine ammonium oxalate stacking sheets with excellent photocatalytic hydrogen evolution activity
Chemcatchem, 2016Co-Authors: Xin Xie, Wei-de ZhangAbstract:A facile strategy to synthesize porous graphitic carbon nitride with stacking nanotubes by Thermal Condensation of melamine–ammonium oxalate stacking sheets is reported. The photocatalytic generation rate of hydrogen over the porous graphitic carbon nitride (99.7 μmol h−1) is nearly 9.5 times as that of pristine g-C3N4 (10.5 μmol h−1). Such enhancement is attributed to the large specific surface area (91.1 m2 g−1), improved visible-light absorption and efficient separation of photogenerated electrons and holes. The strategy of preparing the porous graphitic carbon nitride with modified melamine as a precursor opens a new gate for the regulation of the morphologies of g-C3N4 to get higher photocatalytic activity.
Gregory P Holland - One of the best experts on this subject based on the ideXlab platform.
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the impact of metal doping on fumed silica structure and amino acid Thermal Condensation catalytic properties
Journal of Materials Science, 2021Co-Authors: Haley L Swanson, Suman Pokhrel, Stephen K Davidowski, Lutz Madler, Jeffrey C Brinker, Gregory P HollandAbstract:Fumed silica nanoparticles (FSN) are one of the most common synthetic forms of silica, but prolonged exposure leads to cell toxicity and apoptosis due to reactive oxygen species (ROS) generation and cell membrane perturbation resulting from hydrogen bonding and electrostatic interactions. Increasing attention is being put on synthesizing FSN material that is safer both for workers involved in large-scale industrial production, and consumers coming in contact with FSN additives. In the present work, we explore the molecular structural differences and efficacy of Al- and Ti-metal-doped FSN which has previously been shown to reduce toxicity effects of FSN. We use a combination of 29Si and 27Al solid-state magic angle spinning (MAS) NMR, Raman spectroscopy, and thermogravimetric analysis (TGA) to probe the surface and bulk structure and quantify the adsorption capacity and reactivity of the metal-doped FSN with respect to amino acid Thermal Condensation. Alanine was selected as the amino acid of choice for its simplicity and ubiquity in biochemical reactions. The results indicate that metal doping has a modest impact on the fumed silica molecular structure with a small decrease in amino acid adsorption capacity and Thermal Condensation reactivity as a function of increased metal doping.
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alanine adsorption and Thermal Condensation at the interface of fumed silica nanoparticles a solid state nmr investigation
Journal of Physical Chemistry C, 2015Co-Authors: Chengchen Guo, Gregory P HollandAbstract:Investigating the interface between biomolecules and nanoparticles has attracted considerable attention in recent years since it has great significance in numerous fields including nanotechnology, biomineralization, cancer therapy, and origin of life. In this paper, we present a thorough solid-state NMR study on alanine adsorption and Thermal Condensation on fumed silica nanoparticles. The structure and dynamics at the interface between alanine and fumed silica nanoparticles were probed with a combination of 1H, 13C, and 15N one- and two-dimensional (2D) magic angle spinning (MAS) solid-state NMR methods at different alanine surface coverages and hydration levels. It is illustrated at high surface coverages both crystalline and adsorbed states of alanine exist in the samples while only adsorbed alanine is observed at low surface coverage (approximately a monolayer). At high hydration levels, the adsorbed alanine exhibits enhanced mobility, and both the carboxyl and amine group interact with mobile water m...
Hou Wang - One of the best experts on this subject based on the ideXlab platform.
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visible light driven removal of tetracycline antibiotics and reclamation of hydrogen energy from natural water matrices and wastewater by polymeric carbon nitride foam
Water Research, 2018Co-Authors: Hou Wang, Mingbao Feng, Tong Xiao, Ting Xiong, Huixiang Ang, Xingzhong Yuan, Jia Wei ChewAbstract:Abstract Water and energy are key sustainability issues that need to be addressed. Photocatalysis represents an attractive means to not only remediate polluted waters, but also harness solar energy. Unfortunately, the employment of photocatalysts remains a practical challenge in terms of high cost, low efficiency, secondary pollution and unexploited water matrices influence. This study investigated the feasibility of photocatalysis to both treat water and produce hydrogen with practical water systems. Polymeric carbon nitride foam (CNF) with large surface area and mesoporous structure was successfully prepared via the bubble-template effect of ammonium chloride decomposition during Thermal Condensation. The reaction kinetics, mechanisms, and effect of natural water matrices and wastewater on CNF-based photocatalytic removal of tetracycline hydrochloride (TC-HCl) were systematically investigated. Furthermore, the efficiency of clean hydrogen energy from natural water matrices and wastewater was also evaluated. It was found that the photocatalytic performance of CNF for TC-HCl removal was principally affected by calcination temperature in the presence of NH4Cl. The degradation rates of CNF-4 (calcined at 550 °C) were approximately 1.84, 2.49 and 7.47 times than that of the CNF-2 (calcined at 600 °C), CNF-1 (calcined at 500 °C) and GCN (without NH4Cl), respectively. Results indicate that the improved photocatalytic performance was predominantly ascribed to the large specific surface area, increased availability of exposed active sites, and enhanced transport and separation efficiency of the photogenerated carrier. Based on electron spin resonance, chemical trapping experiment and density functional theory calculation, photoinduced oxidizing species (·O2− and holes) initially attacked the C-N-C fragment of TC molecules, which were finally mineralized to CO2, water and inorganic matters. Under the synergistic influence of water constituents (including acidity and alkalinity, ion species and dissolved organic substances), various water matrices greatly affected the degradation rate of TC-HCl, with the highest removal efficiency of 78.9% in natural seawater, followed by reservoir water (75.0%), tap water (62.3%), deionized water (49.8%), reverse osmosis concentrate (32.7%) and pharmaceutical wastewater (18.9%). Interestingly, low amounts of the emerging microplastics slightly improved TC-HCl removal, whereas high amounts (1.428 × 107 P/cm3) restricted removal due to light absorption and the intrinsic adsorption interaction. Moreover, the photocatalysts were able over repeated usage. Notably, the hydrogen yields rates of polymeric carbon nitride foam were 352.2, 299.8, 184.9 and 94.3 μmol/g/h in natural seawater, pharmaceutical wastewater, water from reservoir and tap water, respectively. This study proves the potential of novel nonmetal porous photocatalyst to simultaneously treat wastewater while converting solar energy into clean hydrogen energy.
Changhai Liu - One of the best experts on this subject based on the ideXlab platform.
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sulfur doped graphitic carbon nitride decorated with zinc phthalocyanines towards highly stable and efficient photocatalysis
Applied Catalysis A-general, 2016Co-Authors: Qian Liang, Miao Zhang, Changhai LiuAbstract:Abstract A series of sulfur-doped graphitic carbon nitride (g-CNS) materials were prepared by Thermal Condensation of a high-quality thiourea and melamine under air atmosphere. When zinc phthalocyanine (ZnTNPc) was combined with g-CNS, the photocatalytic performance of ZnTNPc/g-CNS was 4.4 times higher than that of pure ZnTNPc under visible irradiation. More importantly, the ZnTNPc/g-CNS composites exhibited higher photocatalytic activity for the degradation of methylene blue than ZnTNPc/g-C3N4 under the same conditions. Some typical scavengers were added to identify the active species in the photocatalytic oxidation process. Mott-Schottky curve reveals that the introduction of sulfur atoms in the graphitic carbon nitride not only narrows the band gap but also results in a downshift of the conduction band. The mechanism of the enhanced photocatalytic activity of ZnTNPc/g-CNS is based on the synergetic effect between ZnTNPc and g-CNS, which causes a rapid photo induced charge separation and suppresses the possibility of recombination of electron-hole pairs. Our effects will provide a novel system to increase the number of active species participated in the photocatalytic process, and thus enhance the photocatalytic activity of carbon-based catalysts.
Jia Wei Chew - One of the best experts on this subject based on the ideXlab platform.
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visible light driven removal of tetracycline antibiotics and reclamation of hydrogen energy from natural water matrices and wastewater by polymeric carbon nitride foam
Water Research, 2018Co-Authors: Hou Wang, Mingbao Feng, Tong Xiao, Ting Xiong, Huixiang Ang, Xingzhong Yuan, Jia Wei ChewAbstract:Abstract Water and energy are key sustainability issues that need to be addressed. Photocatalysis represents an attractive means to not only remediate polluted waters, but also harness solar energy. Unfortunately, the employment of photocatalysts remains a practical challenge in terms of high cost, low efficiency, secondary pollution and unexploited water matrices influence. This study investigated the feasibility of photocatalysis to both treat water and produce hydrogen with practical water systems. Polymeric carbon nitride foam (CNF) with large surface area and mesoporous structure was successfully prepared via the bubble-template effect of ammonium chloride decomposition during Thermal Condensation. The reaction kinetics, mechanisms, and effect of natural water matrices and wastewater on CNF-based photocatalytic removal of tetracycline hydrochloride (TC-HCl) were systematically investigated. Furthermore, the efficiency of clean hydrogen energy from natural water matrices and wastewater was also evaluated. It was found that the photocatalytic performance of CNF for TC-HCl removal was principally affected by calcination temperature in the presence of NH4Cl. The degradation rates of CNF-4 (calcined at 550 °C) were approximately 1.84, 2.49 and 7.47 times than that of the CNF-2 (calcined at 600 °C), CNF-1 (calcined at 500 °C) and GCN (without NH4Cl), respectively. Results indicate that the improved photocatalytic performance was predominantly ascribed to the large specific surface area, increased availability of exposed active sites, and enhanced transport and separation efficiency of the photogenerated carrier. Based on electron spin resonance, chemical trapping experiment and density functional theory calculation, photoinduced oxidizing species (·O2− and holes) initially attacked the C-N-C fragment of TC molecules, which were finally mineralized to CO2, water and inorganic matters. Under the synergistic influence of water constituents (including acidity and alkalinity, ion species and dissolved organic substances), various water matrices greatly affected the degradation rate of TC-HCl, with the highest removal efficiency of 78.9% in natural seawater, followed by reservoir water (75.0%), tap water (62.3%), deionized water (49.8%), reverse osmosis concentrate (32.7%) and pharmaceutical wastewater (18.9%). Interestingly, low amounts of the emerging microplastics slightly improved TC-HCl removal, whereas high amounts (1.428 × 107 P/cm3) restricted removal due to light absorption and the intrinsic adsorption interaction. Moreover, the photocatalysts were able over repeated usage. Notably, the hydrogen yields rates of polymeric carbon nitride foam were 352.2, 299.8, 184.9 and 94.3 μmol/g/h in natural seawater, pharmaceutical wastewater, water from reservoir and tap water, respectively. This study proves the potential of novel nonmetal porous photocatalyst to simultaneously treat wastewater while converting solar energy into clean hydrogen energy.