Direct water oxidation via photocatalysis is a four-electron and multiple-proton process which requires high extra energy input to produce free dioxygen gas, making it exacting, especially under ...visible light irradiation. To improve the oxygen evolution reaction rates (OERs) and utilize more visible light, flower-like cobalt hydroxide/oxide (Fw-Co(OH)2/Fw-Co3O4) photocatalysts were prepared and loaded onto graphitic carbon nitride (g-C3N4) by a facile coating method in this work. Influenced by the unique three-dimensional morphologies, the synthesized Fw-Co(OH)2 or Fw-Co3O4/g-C3N4 hybrids reveal favorable combination and synergism reflected by the modified photoelectric activities and the improved OER performances. Attributed to its prominent hydrotalcite structure, Fw-Co(OH)2 shows better cocatalytic activity for g-C3N4 modification compared with that of Fw-Co3O4. Specifically, 7 wt % Fw-Co(OH)2/g-C3N4 photocatalyst exhibits photocurrent density 4 times higher and OER performance 5 times better than pristine g-C3N4. This work unambiguously promotes the application of sustainable g-C3N4 in water oxidation.
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Adsorptive removal of a toxic sulfonamide antibiotic, sulfachloropyradazine (SCP), from aqueous solution was studied on several metal organic frameworks, UiO-66 and ZIF-67, for the ...first time. UiO-66 exhibited a much higher adsorption capacity than ZIF-67, fast kinetics, and easy regeneration for reuse, demonstrating as a promising adsorbent in wastewater treatment processes. The batch adsorption shows an adsorption capacity of SCP at 417mg/g on UiO-66. The kinetic adsorption of SCP on UiO-66 reached equilibrium just in 10min and the kinetics fits accurately with a pseudo 2nd order model. A plausible mechanism was proposed based on pH effect, pKa value of the adsorbate and Zeta potential of UiO-66. The high adsorption is mainly contributed to hydrophobicity and π-π interactions along with electrostatic interactions. Thermodynamic studies show the spontaneous adsorption and exothermic process. The easy regeneration and high adsorption capacity confirms structural stability of the robust UiO-66 in wastewater treatment processes, making it suitable for a large scale application.
The potential to use ethanol as a fuel places solid oxide fuel cells (SOFCs) as a sustainable technology for clean energy delivery because of the renewable features of ethanol versus hydrogen. In ...this work, we developed a new class of anode catalyst exemplified by Ni+BaZr0.4Ce0.4Y0.2O3 (Ni+BZCY) with a water storage capability to overcome the persistent problem of carbon deposition. Ni+BZCY performed very well in catalytic efficiency, water storage capability and coking resistance tests. A stable and high power output was well maintained with a peak power density of 750 mW cm−2 at 750 °C. The SOFC with the new robust anode performed for seven days without any sign of performance decay, whereas SOFCs with conventional anodes failed in less than 2 h because of significant carbon deposition. Our findings indicate the potential applications of these water storage cermets as catalysts in hydrocarbon reforming and as anodes for SOFCs that operate directly on hydrocarbons.
No shortage of water storage: To overcome the persistent problem of carbon deposition, a new class of anode catalysts exemplified by Ni+BaZr0.4Ce0.4Y0.2O3 paves the way for the application of hydrocarbons as an efficient fuel. The water storage capability of these robust proton‐conducting ceramics captures the water produced from the fuel oxidation and releases it to gasify the carbon formed.
A novel thin-film nanocomposite (TFN) nanofiltration membrane has been developed via interfacial incorporation of aminosilanized TiO2 nanoparticles. Polyethersulfone (PES) barrier coating on a porous ...α-Al2O3 ceramic hollow fibre membrane was employed as the substrate layer. TiO2 nanoparticles were incorporated in pure and functionalized forms into trimesoyl chloride (TMC) organic phase and m-phenylenediamine (m-PDA) aqueous phase, respectively. The surface functionalization of TiO2 nanoparticle was confirmed by XRD, FTIR and UV-vis reflectance spectral analysis. Surface properties of the fabricated composite membranes were investigated using SEM, EDX, AFM and contact angle goniometry. Heat resistibility of polyamide layers were examined using thermo-gravimetric analysis (TGA). Membranes intrinsic properties such as: the permeability, selectivity and pore size determination were also elucidated. The silane coupling agent containing amino-functional groups reinforced TiO2 nano fillers for the good dispersion inside the polyamide skin layer by reducing their surface energy. At ultra-low concentration (0.005wt.%), the functionalized TiO2 nanoparticles improved the salt rejection to 54% as well as water flux to 12.3l/m2h. By incorporating a higher concentration of TiO2 nanoparticles, water flux was increased up to 2-fold compared with the pure polyamide membrane with negligible rejection loss. These results demonstrated competency of using functionalized inorganic nanoparticles to increase the product flux and the separation efficiency.
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► Polyamide TFN membranes were prepared on hollow-fiber α-alumina support. ► Functionalization of TiO2 nanoparticles assisted to overcome the agglomeration. ► Thin-film gives the best performance at 0.005wt.% of functionalized TiO2. ► Uniform dispersion of functionalized TiO2 results better thermal stability. ► Improvement in the permeability as well as selectivity has obtained.
In this study, a series of thin film nanocomposite membranes was developed by coating a surface-modified porous poly (vinylidene fluoride) (PVDF) support with poly (vinyl alcohol) (PVA) doped ...solution containing TiO2 nanoparticles. In order to improve the interfacial adhesion of nanoparticles in the PVA blend, an endothermic carboxylation reaction under acidic conditions was carried out on the TiO2 surface using chloroacetic acid. Electron microscopy studies identified various topographies upon functionalization of the coating and incorporation of TiO2 nanoparticles. The carboxylation of TiO2 nanoparticles promoted particle dispersion within the PVA doped solution with significantly reduced particle agglomeration, demonstrating a potential solution to a significant difficulty in the synthesis of state-of-the-art nanocomposite membranes. Furthermore, the carboxylate functional groups on the TiO2 surface facilitated a strong interfacial crosslinking reaction with the hydroxyl groups in the PVA chains, conferring excellent interface integration between the nanoparticle and the polymer matrix. The high performance of this new carboxylated thin film nanocomposite membrane is evidenced by the improved membrane performance including solute rejection, antifouling properties and flux recovery ratio.
•A high performance PVDF-based PVA and TiO2-nanocomposite membrane was developed.•The modified TiO2 particle provides good dispersion and adhesion with the polymer.•Solute rejection and antifouling properties of the resultant membrane were improved.
Perovskite oxides are highly promising electrodes for oxygen-ion-intercalation-type supercapacitors owing to their high oxygen vacancy concentration, oxygen diffusion rate, and tap density. Based on ...the anion intercalation mechanism, the capacitance is contributed by surface redox reactions and oxygen ion intercalation in the bulk materials. A high concentration of oxygen vacancies is needed because it is the main charge carrier. In this study, we propose a B-site cation-ordered Ba2Bi0.1Sc0.2Co1.7O6−δ as an electrode material with an extremely high oxygen vacancy concentration and oxygen diffusion rate. A maximum capacitance of 1050 F g–1 was achieved, and a high capacitance of 780 F g–1 was maintained even after 3000 charge–discharge cycles at a current density of 1 A g–1 with an aqueous alkaline solution (6 M KOH) electrolyte, indicating an excellent cycling stability. In addition, the specific volumetric capacitance of Ba2Bi0.1Sc0.2Co1.7O6−δ reaches up to 2549.4 F cm–3 based on the dense construction and high tap density (3.2 g cm–3). In addition, an asymmetric supercapacitor was constructed using activated carbon as a negative electrode, and it displayed the highest specific energy density of 70 Wh kg–1 at the power density of 787 W kg–1 in this study.
Volatile organic compounds (VOCs) are the major pollutants in indoor air, which significantly impact indoor air quality and thus influencing human health. A long-term exposure to VOCs will be ...detrimental to human health causing sick building syndrome (SBS). Photocatalytic oxidation of VOCs is a cost-effective technology for VOCs removal compared with adsorption, biofiltration, or thermal catalysis. In this paper, we review the current exposure level of VOCs in various indoor environment and state of the art technology for photocatalytic oxidation of VOCs from indoor air. The concentrations and emission rates of commonly occurring VOCs in indoor air are presented. The effective catalyst systems, under UV and visible light, are discussed and the kinetics of photocatalytic oxidation is also presented.
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▶ Nanosized Co/SiO2 exhibits high activity in activation of peroxymonosulphate. ▶ Co precursors affect the properties of Co/SiO2. ▶ Co/SiO2 from nitrate precursor presents high ...efficiency for phenol degradation. ▶ Stability of Co/SiO2 is higher than other systems.
Nanosized silica supported Co catalysts were prepared using three different Co(II) precursor salts, nitrate (N), chloride (Cl) and acetate (Ac). The physicochemical properties of the three Co/SiO2 catalysts were characterized by several techniques, such as XRD, SEM, TEM, FT-IR, FT-Raman and UV–vis diffuse reflectance spectroscopy, and the catalytic activity in heterogeneous activation of peroxymonosulphate to produce sulphate radicals for phenol degradation was investigated. It was found that anions of Co precursor affected the interaction between Co metal and support, influencing the properties of the catalysts and their catalytic activity. All three Co/SiO2 catalysts exhibited high activity in sulphate radical generation and phenol degradation. The Co/SiO2 prepared using Co nitrate showed a strong Co and support interaction by forming Co3O4 and Co2SiO4 species and exhibited less leaching of Co. The rate of phenol oxidation on Co/SiO2 followed an order of Co/SiO2–Cl>Co/SiO2–Ac>Co/SiO2–N while the stability of the three catalysts presented an opposite trend. Co/SiO2–N still exhibited higher activity after three-run tests while the other two catalysts showed significant deactivation. Phenol degradation on Co/SiO2 followed zero order kinetics and activation energies of Co/SiO2–N, Co/SiO2–Cl, Co/SiO2–AC were obtained as 67.5, 75.1 and 61.7kJ/mol, respectively.
Highly porous and monodisperse manganese oxides with different particle sizes were synthesized via a one-pot hydration and annealing process. Their catalytic performances were evaluated by the ...activation of peroxymonosulfate (PMS) to degrade phenol in aqueous solutions. The effects of sphere size (200–500 nm), calcination temperature (200–1000 °C), catalytic stability (leaching problem and reusability), reaction kinetics, and reaction temperature (25–45 °C) on the degradation efficiencies as well as the degradation mechanism were comprehensively studied. The small sized catalyst displayed the best efficiency in decomposition of phenol, and the annealing treatments would significantly improve the catalytic stability.
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