Density functional simulations of condensed phase water are typically inaccurate, due to the inaccuracies of approximate functionals. A recent breakthrough showed that the SCAN approximation can ...yield chemical accuracy for pure water in all its phases, but only when its density is corrected. This is a crucial step toward first-principles biosimulations. However, weak dispersion forces are ubiquitous and play a key role in noncovalent interactions among biomolecules, but are not included in the new approach. Moreover, naïve inclusion of dispersion in HF-SCAN ruins its high accuracy for pure water. Here we show that systematic application of the principles of density-corrected DFT yields a functional (HF-r
SCAN-DC4) which recovers and not only improves over HF-SCAN for pure water, but also captures vital noncovalent interactions in biomolecules, making it suitable for simulations of solutions.
Density functional theory (DFT) is usually used self-consistently to predict chemical properties, but the use of the Hartree–Fock (HF) density improves energetics in certain, well-characterized ...cases. Density-corrected (DC) DFT provides the theory behind this, but unrestricted Hartree–Fock (UHF) densities yield poor energetics in cases of strong spin contamination. Here we compare with restricted open-shell HF (ROHF) across 13 different functionals and two DC-DFT methods. For significant spin contamination, ROHF densities outperform UHF densities by as much as a factor of 3, depending on the energy functional, and ROHF-DFT improves over self-consistent DFT for most of the tested functionals. We refine the DC(HF)-DFT algorithm to use ROHF densities in cases of severe spin contamination.
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•Platinum(Pt) was recovered from spent automobile catalyst leachate by bio-sorption.•Nanocellulose from various sources and types are modified with polyethyleneimine(PEI).•Cellulose ...nano fibril from tunicate(T-CNF) exhibits the highest PEI grafting density.•Pure cellulose form and open porous structure of T-CNF enhances the PEI density.•Pt adsorption capacity is proportionally increased by PEI density on nanocellulose.
Nanocellulose is a promising biosorbent for the recovery of precious metals from waste streams. A variety of nanocelluloses exhibit significant different properties that depend on the natural source and type. In this study, cellulose nanofibrils(P-CNF) and cellulose nanocrystals(P-CNC) obtained from hard wood pulp and CNF from tunicates(T-CNF) were evaluated for their ability to recover platinum(Pt) after modification with polyethyleneimine(PEI). The PEI grafting density on each nanocellulose was distinct, resulting in significant variations in the Pt adsorption performance. The Pt adsorption capacity of the PEI-modified nanocelluloses followed the order T-CNF>>P-CNC > P-CNF. The inherent characteristics of T-CNF, that is, the negative charge and high surface area caused by open porous structure, were found attributed to the grafting of ≈40% PEI and the excellent Pt adsorption capacity(≈600 mg/g). Also PEI-modified T-CNF exhibited high selectivity towards Pt in the presence of other metals. Finally, PEI modified T-CNF was applied for Pt recovery from simulated spent automobile catalyst leachate to prove feasibility in a real application.
•CMCNF is used as a filler to enhance mechanical property of GO fiber.•GO/CMCNF composite fiber is cross-linked by employing Fe3+ ion as a coagulant.•GO/CMCNF composite fiber shows high packing ...density and efficient load transfer.•GO/CMCNF fiber shows excellent heavy metal uptake with facile recovery after use.•GO/CMCNF fiber is produced by a typical wet-spinning process enabling scalability.
Recently, graphene oxide(GO) has gained much attention for heavy metal removal due to its high surface area and lots of functional groups on the surface. However, GO itself in powder form is far away from practical adsorbents because it remains dispersed in liquid phase which causes difficulty in the separation from effluent. In this study, GO/carboxymethyl cellulose nanofibril (CMCNF) composite fiber(CF) is developed as an efficient and durable adsorbent. Cross-linked GO/CMCNF CF was continuously produced by employing Fe3+ ion as a coagulant during a typical wet-spinning process. Based on multiple interactions such as ionic bonding and electrostatic interactions between Fe3+ and carboxyl group on CMCNF, the CF exhibits enhanced mechanical property than pure GO fiber. GO/CMCNF-Fe3+ CF showed efficient lead (Pb2+) uptake with successful adsorbent recovery, which indicates durable and cost-competitive fiber type adsorbent for heavy metal ions.
4-Nitrophenol (4-NP) is a hazardous aromatic compound widely used for various industries. Catalytic reduction of 4-NP using metal nanoparticles (NPs) is a highly effective method to treat 4-NP from ...waste effluent. Even though lots of methods have investigated to prepare efficient metal NPs composites, the nano and/or micro size of composites makes it hard to recover after wastewater treatment, limiting its practical use. Here, we fabricate 3-dimensional polyethylene imine grafted cellulose nanofibril (CNF-PEI) aerogel as a porous support material for platinum (Pt) NPs to practically and effectively treat 4-NP from wastewater. The Pt NPs are formed in-situ mode on cylindrical CNF-PEI aerogel by adsorption reaction with amine groups of PEI and subsequently reduction with NaBH4. Control of PEI grafting density and the initial concentration of Pt ions allows manipulation of the loading mass, size, and distribution of Pt NPs on 3D scaffold of CNF-PEI aerogel. The composite aerogel shows high catalytic activity for conversion of 4-NP. The 4-NP conversion activity is strongly affected by the size of Pt NPs and effective surface area of aerogels. The 2.74 nm size Pt NPs with even distribution in the aerogel show fast reaction kinetics (k = 0.12 min−1). Finally, 4-NP reduction efficiency does not decrease during 5 times reuse cycle of Pt NPs loaded CNF-PEI aerogel. This CNF-PEI aerogel loaded with Pt NPs is recovered easily from wastewater after treatment, so it is reusable and offers high potential as a practical recyclable environmental catalyst.
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•Platinum nanoparticles (Pt NPs) loaded cellulose nanofibril (CNF) aerogel was prepared.•Surface of CNF aerogel was modified with polyethylene imine (PEI) to anchor Pt NPs.•Distribution and size of Pt NPs on 3D CNF aerogel could be systematically controlled.•Composite aerogel shows excellent efficiency in reductive removal of 4-nitrophenol.
Nitrophenols(NPs) are highly toxic compounds that occur in various industrial effluents. Herein, we investigated Cu nanoparticle-loaded cellulose nanofibril (CNF/PEI-Cu) aerogels as a catalyst for ...degrading 4-nitrophenol (4NP) in the wastewater. Non-noble metal based low-cost catalyst material and easily scalable preparation method make CNF/PEI-Cu aerogel as an appropriate catalyst for practical application in 4NP wastewater treatment. Our strategy to improve the loading amount of homogeneously distributed Cu nanoparticles was to functionalize a CNF aerogel using polyethylene imine (PEI), which can bind Cu2+ ions. Porous CNF aerogels with homogenously distributed 20–40 nm Cu nanoparticles were obtained by adsorbing Cu2+ ions and chemically reducing them to Cu metal. The FTIR, XRD, SEM, XPS and ICP-OES analysis were used to confirm the in-situ formation of Cu nanoparticles. In the presence of the CNF/PEI-Cu aerogels, 4NP was effectively reduced to 4-aminophenol (4AP) without loss of the Cu nanoparticles. The activation energy (Ea) and reaction rate constant (kapp) of the catalytic 4NP reduction reaction by the CNF/PEI2-Cu aerogels were calculated to be Ea = 39.56 kJ mol−1 and kapp = 0.770 min−1, respectively. The Ea is similar or even smaller than the Ea values of the corresponding reactions involving noble-metal catalysts, demonstrating that the CNF/PEI-Cu aerogels developed in the present study have strong potential as practical and economical catalysts.
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•A cost-effective and scalable catalyst is prepared for nitrophenol(NP) wastewater treatment.•Cu loaded cellulose nanofibril(CNF/PEI-Cu) aerogel promotes 4NP reduction to 4-aminophenol.•Thermodynamic and kinetic behavior of 4NP reduction by CNF/PEI-Cu is investigated.•Activation energy of 4NP reduction reaction is significantly decreased by CNF/PEI-Cu.
Almost all empirical parametrizations of dispersion corrections in DFT use only energy errors, thereby mixing functional and density-driven errors. We introduce density and dispersion-corrected DFT ...(D2C-DFT), a dual-calibration approach that accounts for density delocalization errors when parametrizing dispersion interactions. We simply exclude density-sensitive reactions from the training data. We find a significant reduction in both errors and variation among several semilocal functionals and their global hybrids when tailored dispersion corrections are employed with Hartree-Fock densities.Almost all empirical parametrizations of dispersion corrections in DFT use only energy errors, thereby mixing functional and density-driven errors. We introduce density and dispersion-corrected DFT (D2C-DFT), a dual-calibration approach that accounts for density delocalization errors when parametrizing dispersion interactions. We simply exclude density-sensitive reactions from the training data. We find a significant reduction in both errors and variation among several semilocal functionals and their global hybrids when tailored dispersion corrections are employed with Hartree-Fock densities.
Weavable sensing fibers with superior mechanical strength and sensing functionality are crucial for the realization of wearable textile sensors. However, in the fabrication of previously reported ...wearable sensing fibers, additional processes such as reduction, doping, and coating were essential to satisfy both requirements. The sensing fibers should be continuously synthesized in a scalable process for commercial applications with high reliability and productivity, which was challenging. In this study, we first synthesize mass-producible wearable sensing fibers with good mechanical properties and sensing functionality without additional processes by incorporating carbon nanotubes (CNTs) into distinct nanocellulose. Nanocellulose extracted from tunicate (TCNF) is homogeneously composited with single-walled CNTs, and composite fibers (TCNF/CNT) are continuously produced in aligned directions by wet spinning, facilitating liquid-crystal properties. The TCNF/CNT fibers exhibit a superior gas (NO2)-sensing performance with high selectivity and sensitivity (parts-per-billion detection). In addition, the TCNF/CNT fibers can endure complex and harsh distortions maintaining their intrinsic sensing properties and can be perfectly integrated with conventional fabrics using a direct weaving process. Our meter-scale scalable synthesis of functional composite fibers is expected to provide a mass production platform of versatile wearable sensors.
Fiber‐shaped supercapacitors (FSSCs) are the most state‐of‐the‐art power supplies suitable for wearable devices, but the intrinsically limited cylindrical space of fibers restricts their high ...electrochemical performance, which must be overcome with a delicate and systematic architectural process. Here, a simple but effective 3D architectural strategy for fabricating FSSCs with high performance and flexibility is proposed. Highly conductive liquid crystal spun carbon nanotube fiber (CNTF) is an excellent 1D core fiber for the electrophoretic deposition of graphene oxide (GO). The deposited GO forms a vertical 3D structure on the CNTF (VG@CNTF), which can be successfully preserved by a consecutive coating of pseudocapacitive active materials onto the surface of VG. Notably, a solid‐state asymmetric FSSC shows an outstanding performance of 65 Wh kg−1 at 100 kW kg−1 and exceptional stability and flexibility (capacitance retention of 98.60% at bending angles of 90° and 93.1% after 5000 bending cycles). This work can provide new insight into the development of high‐performance FSSCs for practical wearable applications.
A simple but effective 3D architectural strategy for fabricating fiber‐shaped supercapacitors (FSSCs) with high electrochemical performance and flexibility using electrochemical deposition is reported. The prepared FSSCs show superior energy density and power density. This study highlights the great possibility of 3D architectured FSSCs for future wearable applications.
Humidity sensors are essential components in wearable electronics for monitoring of environmental condition and physical state. In this work, a unique humidity sensing layer composed of ...nitrogen‐doped reduced graphene oxide (nRGO) fiber on colorless polyimide film is proposed. Ultralong graphene oxide (GO) fibers are synthesized by solution assembly of large GO sheets assisted by lyotropic liquid crystal behavior. Chemical modification by nitrogen‐doping is carried out under thermal annealing in H2(4%)/N2(96%) ambient to obtain highly conductive nRGO fiber. Very small (≈2 nm) Pt nanoparticles are tightly anchored on the surface of the nRGO fiber as water dissociation catalysts by an optical sintering process. As a result, nRGO fiber can effectively detect wide humidity levels in the range of 6.1–66.4% relative humidity (RH). Furthermore, a 1.36‐fold higher sensitivity (4.51%) at 66.4% RH is achieved using a Pt functionalized nRGO fiber (i.e., Pt‐nRGO fiber) compared with the sensitivity (3.53% at 66.4% RH) of pure nRGO fiber. Real‐time and portable humidity sensing characteristics are successfully demonstrated toward exhaled breath using Pt‐nRGO fiber integrated on a portable sensing module. The Pt‐nRGO fiber with high sensitivity and wide range of humidity detection levels offers a new sensing platform for wearable humidity sensors.
Nitrogen‐doped graphene fiber functionalized by Pt nanoparticles (Pt‐nRGO fiber) is integrated on a flexible and transparent polyimide substrate for application in real‐time and on‐site monitoring of humidity. This work demonstrates the humidity sensing characteristic of Pt‐nRGO fiber, which further expands versatility of graphene‐based fiber in wearable sensing electronics.
