查看更多>>摘要：Based on the strategy that electrocatalysts can be used as additives to improve the performance of photocatalysts, and the unique metalloid properties of tungsten nitride (WN), it can form a Schottky junction with the semiconductor at the heterogeneous interface to improve the photocatalytic performance of semiconductor catalysts. In this paper, WN with excellent electrical conductivity was selected as a new noble-metal-free co-catalyst to improve the photoreduction hydrogen (H-2) evolution performance of CdS nanoparticles (NPs). Firstly, WN nanosheets were prepared by sol-gel method; then, a novel and noble-metal-free heterojunction photocatalyst, which is CdS NPs deposited on the surface of WN, was successfully fabricated via one-pot solvothermal method. Under visible light irradiation, the H-2 production rate of the WN/CdS composite catalyst is 24.13 mmol/g/h, which is 9.28 times that of pure CdS NPs. The observably boosted H-2 generation activity could be ascribed to the broadened visible-light absorption and intimate interfacial contact between CdS NPs and WN engenders Schottky junction. This study provides a novel and cost-effective approach for designing efficient noble-metal-free photocatalysts and improving H-2 evolution activity of CdS under visible-light-driven photocatalytic water splitting. (C) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Solar steam generation (SSG) is one of the promising technologies for seawater desalination and contaminated water purification. However, SSG devices are always restricted by poor insulation performance, insufficient solar spectrum absorption and serious salt-fouling. Here, a double-layered novel SSG system was fabricated by using poly(ionicliquid)s gels with hollow SiO2 microspheres in-situ doping to enhance the thermal insulation of lower layer, and co-modified the top surface by polypyrrole (PPy) and silver particles to strengthen the solar absorption capability. Benefiting from the low thermal conductivity (0.082 W m(-1) k(-1)), strong light absorption (ca. 96%) and adequate water transport capability of poly(ionic liquid)s gels. As SSG device, a superb photothermal conversion efficiency of 90.5% is achieved under 1 sun illumination. Moreover, the poly(ionic liquid)s gels based SSG system also shows good desalination performance in artificial sea water and high concentration brine, and the purified water from artificial seawater can achieve the WHO's standard for drinking water. Therefore, this work combined attractive in-situ doping and co-modified strategies for fabricating high performance and thus shows significant potential for real applications. (C) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Designing photothermal transducing agents (PTAs) with enhanced photothermal conversion efficiency (PCE) holds essential importance for photothermal tumor eradication applications. Currently, it is an effective way to improve the photothermal efficiency by designing the energy level transition leading to the enhancement of UV absorption. To address the challenge, we develop novel Prussian blue@polyacrylic acid/copper sulfide Janus nanoparticles (PB@PAA/CuS JNPs) via selective coating of PAA nanohemisphere on one of the surfaces of PB NPs followed by the further formation of CuS on the PAA template. The experiments show that the energy level transition occurs between Janus structure. Besides, it offers enhanced absorption over NIR-I and NIR-II dual windows. The muscle tissue penetration studies suggest that the PB@PAA/CuS JNPs have deeper tissue penetration in the 1064 nm laser irradiation group, indicating their potential for treating deep-tissue-seated tumors. In a word, the unique PB@PAA/CuS JNPs show an enhanced tumor inhibitory effect over the NIR-I and NIR-II dual windows, which will open up new opportunities for improving PTT efficiency by the rational nanostructural design of PTAs. (c) 2022 Published by Elsevier Inc.
查看更多>>摘要：The use of templates in materials chemistry is a well-established approach for producing membrane bounded hollow spheres used for microencapsulation applications, but also in synthetic biology to assemble artificial cell-like compartments. Sacrificial solid or gel micro-particles, but also liquid-like oil-in-water or water-in-oil emulsion droplets are routinely used as templates to produce capsules. Yet, disruption of the core sacrificial material often requires harsh experimental conditions, such as organic solvents, which limits the use of such approach to encapsulate fragile solutes, including biomolecules. Recently, water-in-water emulsion droplets have emerged as promising alternative templates to produce capsules in solvent-free conditions. These water-in-water droplets result from liquid-liquid phase separation in dilute aqueous polymer or surfactants solutions. Their ease of preparation, the large palette of components they can be assembled from and the lack of harsh solvent or oil used for their production make water-in-water emulsions of practical importance in materials chemistry. Water-in-water droplets can also spontaneously sequester solutes by equilibrium partitioning, which provides a simple strategy to locally accumulate molecules of interest and encapsulate them in capsules after interfacial shell formation. Here, we review recent works that employ water-in-water emulsion droplets to prepare capsules and suggest possible additional applications in materials chemistry. (c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
查看更多>>摘要：Hypothesis: Gels made from synthetic polymers have improved the cleaning of artifacts, but there is the strong need to elaborate new systems through an all-green approach, developing materials with higher eco-compatibility while retaining optimal efficacy. Rice starch (RS) is a renewable biopolymer with high potential for formulating sustainable gels from composites with synthetic polymers, but its interaction with the latter in composite structures is poorly understood. Experiments: Poly (vinyl alcohol) (PVA) and RS were used to obtain biocomposite hydrogels through a robust and "green" freeze-thawing route. For the first time, extensive understanding of these composites was tackled by investigating their gel structure and rheological behavior. The cleaning effectiveness of the PVA/RS gels was assessed on soiled modern painting mock-ups, whose water-sensitiveness makes their cleaning too risky using traditional tools. Findings: The composites behave as strong gels whose structure and viscoelastic response are controlled tuning the PVA/RS ratio. X-ray scattering and thermal analysis suggested the formation of hybrid PVA-RS links. Starch amylopectin likely acts as a porogen, while amylose forms hydrogen bonds with PVA. The gels adhere to rough paint layers and remove soil effectively without detectable residues. Overall, the PVA/RS composites are highly effective and provide a significant step forward in the formulation of eco-sustainable cleaning formulations. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：The evaporation of a colloidal droplet on a solid surface produces a ring-like structure at the pinned contact line due to induced capillary flow, also known as the coffee-ring effect (CRE). However, the addition of certain additives can significantly reduce CRE, whose physical origin remains in debate. In this study, the time-resolved low field (LF)-NMR technique highlights the effect of different water fractions in colloidal droplets on the ultimate distribution of silica nanoparticles during evaporation. With the assistance of H-1 T-2 relaxometry, the impact of decreasing evaporation rate (J) and additives on the fractions of bound, trapped, and free water can be obtained. Utilizing the T-2 Carr-Purcell-Meiboom-Gill (CPMG) sequence approach, in-situ tracking during droplets evaporation, with varying was obtained to conclude the minimum existence time of bound water required during evaporation for CRE suppression. As the droplet J decreases, the competition between the time scale of totally droplet evaporation t(F) and the time spent of bound water during evaporation t(B) may influence the ring formation. Experimentally a shorter duration of t(B) t(F) <= 0.5 is required for formating the coffee ring structure and successfully suppressed when its existence time surpasses a particular threshold >= 0.5. (C) 2022 Published by Elsevier Inc.
查看更多>>摘要：Designing nanostructure based robust catalyst for the electrochemical water splitting is the great task in the energy conversion field to accomplish high electrical conductivity, low overpotential and long lasting activity. Herein, the electrochemical overall water splitting is reported by using the hydrothermally synthesized binder free cobalt iron phosphate thin films on low cost stainless steel substrates as a conducting backbone for the first time. The effect of composition ratio variation of cobalt and iron was studied on the structural, compositional, morphological, and surface electronic properties by conducting various characterizations which results in amorphous hydrous cobalt iron phosphate having mesoporosity. The as synthesized cobalt iron phosphate having composition ratio (50:50 of Co:Fe) exhibits excellent electrochemical OER and HER catalytic water splitting performance. Best performing electrode exhibits smallest overpotentials of 251.9 mV and 55.5 mV for OER and HER respectively at 10 mA/cm(2) current density. To split water molecule into the H-2 and O-2 by overall water splitting in same alkaline medium, the potential of 1.75 V was required after long duration (100 h) catalysis. Overall analysis confirms the cobalt iron phosphate thin films are outstanding and robust for the hydrogen production as clean renew-able energy source. (C) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：The exploration and preparation of inexpensive, high-performance and stable catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of significant imperativeness, yet is still on the way. In this study, a facile operation protocol is presented for constructing an exquisite threedimensional coral reef-like carbon nanotube assembly bridged with N-doped graphene (assigned as 3D CNTAs-NG, which represented carbonization products at 900 degrees C) as highly efficient and durable ORR/ OER electrocatalysts. It does not require the introduction of reductive atmosphere. In this tactic, the dicyanamide ligand on the Co-MOF not only was instrumental in the introduction of nitrogen but also acted as the inducer of carbon nanotubes (CNTs) to lock the metallic Co in graphitic carbon layers. Graphene oxide (GO) is chosen as a matrix to pin the CNTs and ensure the uniform distribution of CNTs. The obtained CNTAs-NG structure possesses 3D open porous texture, abundant defects, desired nitrogen bonding type and high specific surface area, providing them with excellent ORR and OER properties. As such, the optimized 3D CNTAs-NG sample shows high onset potential (E-onset = 0.97 V vs. RHE) and half-wave potential (E-1/2 = 0.85 V vs. RHE) for ORR and overpotential of 340 mV at 10 mA.cm(-2) for OER. Meanwhile, the prepared optimum catalyst exhibited outstanding durability for ORR and OER in alkaline solutions. This work may pave significant concepts for the synthesis of highly active bifunctional electrocatalysts with intriguing architectures and compositions. (C) 2022 Elsevier Inc. All rights reserved.
Choi, SeongcheolVazquez-Duhalt, RafaelGraeve, Olivia A.
17页
查看更多>>摘要：Hypothesis: We describe the deposition behavior of monodispersed silica nanoparticles on polystyrene spherical particles by using modified pairwise DLVO (Derjaguin-Landau-Verwey-Overbeek) interaction force profiles at pH values between two and twelve. Our modified model contains a new nonlinear charge regulation parameter that considers redistribution of ions, which allows us to realistically express the electrical double layer (EDL) interaction forces. Experiments: Silanol-terminated silica nanoparticles (7.6 +/- 0.4 nm), L-lysine-covered silica nanoparticles (7.8 +/- 0.4 nm), and polyallylamine hydrochloride-covered polystyrene (PAH/PS) particles (348 +/- 1 nm) were synthesized. Then, each type of silica nanoparticle was deposited on the PAH/PS particles at a range of pH values. Findings: Our new regulation parameter describes the realistic redistribution of charges governed by pH, total salt concentration, ionic strength of solution, and separation distance of particles. We find that this regulation parameter can be roughly approximated from the absolute values of theoretically calculated surface charge density and potential distributions, as well as experimentally measured f-potentials. Morphological analysis using electron microscopy of the experimental systems shows that the modified pairwise DLVO interaction forces exceptionally describe the deposition behavior of the silica nanoparticles physically adsorbed on the PAH/PS particle substrates. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Carrier separation and surface reaction kinetic are two main bottlenecks limiting photocatalytic efficiency of photocatalysts towards an industrial level. In this regard, heterostructures and defects engineering have been proven to be effective strategies for addressing the two issues. However, the integrated construction of heterostructures and defects has been reported rarely. Herein, a facile in-situ photodeposition strategy has been developed to grow CdS nanocrystals on MnO2-x nanorods with rich oxygen vacancies (VO) as a direct Z-scheme photocatalyst for boosting water oxidation. It has been found that the Cd2+ ions accept photoelectrons from MnO2-x under irradiation for the in-situ growth of CdS nanocrystals, which enables a close contact between the two components, providing high-speed electron-transport channels for photocatalysis. Meanwhile, the photooxidation half reactions extract surface lattice oxygen, leading to the increase of VO content in MnO2-x, which supplies abundant active sites for oxygen evolution. Owing to the synergistic effects of VO and Z-scheme systems, the optimized MnO2-x/ CdS photocatalyst displays a dramatically enhanced photocatalytic activity with an O2 production rate of 779 lmol g-1h-1 under visible-light irradiation without any cocatalysts, which is 2.33 times higher than the bare MnO2-x. This work reveals the cooperative manipulation of VO and CdS nanocrystals on MnO2-x for achieving efficient photocatalysis, providing new insights into the construction of high-performance photocatalysts via a combined strategy of Z-scheme heterostructures and surface defects. (c) 2022 Elsevier Inc. All rights reserved.
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