Electrochemical production of hydrogen from water has been directed to the search for non-noble metal based and earth-abundant catalysts. In this work, we propose a novel cost-effective catalyst, ...molybdenum phosphide that exhibits high activity towards the hydrogen evolution reaction (HER) in both acid and alkaline media even in bulk form. Comparative analysis of Mo, Mo sub(3)P and MoP as catalysts for HER clearly indicates that phosphorization can potentially modify the properties of the metal and different degrees of phosphorization lead to distinct activities and stabilities. Theoretical calculations by density functional theory also show that a simple phosphorization of molybdenum to form MoP introduces a good 'H delivery' system which attains nearly zero binding to H at a certain H coverage. With the combination of experimental results and theoretical calculations, this work has enlightened a new way of exploring cost-effective catalysts for HER.
•Two major aspects of CO2 reduction are to reduce the dependence on fossil fuels and reduction of atmospheric CO2.•CO2 is electrochemically reduced to various useful chemicals using solid oxide fuel ...cells, metal electrodes in aqueous solution and metal complexes.•Reduction of CO2 using solid oxide fuel cells also generates power.
In this review article, we report the development and utilisation of fuel cells, metal electrodes in aqueous electrolyte and molecular catalysts in the electrochemical reduction of CO2. Fuel cells are able to function in both electrolyser and fuel cell mode and could potentially reduce CO2 and produce energy at the same time. However, it requires considerably high temperatures for efficient operation. Direct reduction using metal electrodes and molecular catalysts are possible at room temperatures but require an additional applied potential and generally have low current densities. Density functional theory (DFT) studies have been used and have begun to unveil possible mechanisms involved which could lead to improvements and development of more efficient catalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Owing to their small size, biocompatibility, unique and tunable photoluminescence, and physicochemical properties, graphene quantum dots (GQDs) are an emerging class of zero‐dimensional materials ...promising a wide spectrum of novel applications in bio‐imaging, optical, and electrochemical sensors, energy devices, and so forth. Their widespread use, however, is largely limited by the current lack of high yield synthesis methods of high‐quality GQDs. In this contribution, a facile method to electrochemically exfoliate GQDs from three‐dimensional graphene grown by chemical vapor deposition (CVD) is reported. Furthermore, the use of such GQDs for sensitive and specific detection of ferric ions is demonstrated.
A facile and high‐yield synthesis method for high quality and strongly photoluminescent graphene quantum dots (GQDs) by electrochemically exfoliating free standing three dimensional graphene foam is demonstrated. The synthesized GQDs are utilized for specific optical detection of ferric ions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Graphene quantum dots (GQDs) are a new class of fluorescent reporters promising various novel applications such as bio-imaging, optical sensing and photovoltaics. They have recently attracted ...enormous interest because of their extraordinary and tunable optical, electrical, chemical and structural properties. However, the widespread use of GQDs is hindered by the poor understanding of their photoluminescence (PL) mechanisms. Using density-functional theory (DFT) and time-dependent DFT calculations, we reveal that the PL of a GQD can be sensitively tuned by its size, edge configuration, shape, attached chemical functionalities, heteroatom doping and defects. In addition, it is discovered that the PL of a large GQD consisting of heterogeneously hybridized carbon network is essentially determined by the embedded small sp 2 clusters isolated by sp 3 carbons. This study not only provides an explanation to the previous experimental observations but also provides insightful guidance to develop methods for the controllable synthesis and engineering of GQDs.
The total and partial solubility parameters (dispersion, polar and hydrogen‐bonding solubility parameters) of ten ionic liquids were determined. Intrinsic viscosity approaches were used that ...encompassed a one‐dimensional method (1D‐Method), and two different three‐dimensional methods (3D‐Method1 and 3D‐Method2). The effect of solvent type, the dimethylacetamide (DMA) fraction in the ionic liquid, and dissolution temperature on solubility parameters were also investigated. For all types of effect, both the 1D‐Method and 3D‐Method2 present the same trend in the total solubility parameter. The partial solubility parameters are influenced by the cation and anion of the ionic liquid. Considering the effect on partial solubility parameters of the solvent type in the ionic liquid, it was observed that in both 3D methods, the dispersion and polar parameters of a 1‐ethyl‐3‐methylimidazolium acetate/solvent (60:40 vol %) mixture tend to increase as the total solubility parameter of the solvent increases.
Viewing the Mix in 3D: The solvation power of ionic liquids and ionic liquid/solvent mixtures was studied by using an intrinsic viscosity method that allowed the determination of Hildebrand and Hansen solubility parameters, in particular, dispersion, polar and hydrogen‐bonding solubility parameters. These partial solubility parameters can be visualized as coordinates in a 3D diagram, allowing illustration of the miscibility of different materials.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The synthesis and reactivity of a silyliumylidene cation stabilized by an amidinate ligand and 4‐dimethylaminopyridine (DMAP) are described. The reaction of the amidinate silicon(I) dimer LSi:2 (1; ...L=PhC(NtBu)2) with one equivalent of N‐trimethylsilyl‐4‐dimethylaminopyridinium triflate 4‐NMe2C5H4NSiMe3OTf and two equivalents of DMAP in THF afforded LSi(DMAP)OTf (2). The ambiphilic character of 2 is demonstrated from its reactivity. Treatment of 2 with 1 in THF afforded the disilylenylsilylium triflate L′2(L)SiOTf (3; L′=LSi:) with the displacement of DMAP. The reaction of 2 with K{HB(iBu)3} and elemental sulfur in THF afforded the silylsilylene LSiSi(H){(NtBu)2C(H)Ph} (4) and the base‐stabilized silanethionium triflate LSi(S)DMAPOTf (5), respectively. Compounds 2, 3, and 5 have been characterized by X‐ray crystallography.
1 becomes 2: The singlet silyliumylidene cation 2, which is stabilized by both an amidinate ligand and 4‐dimethylaminopyridine (DMAP), can be synthesized by the reaction of the amidinate SiI dimer 1 with N‐trimethylsilyl‐4‐dimethylaminopyridinium triflate and DMAP (see scheme). The ambiphilic character of 2 can be demonstrated by its reactivity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•This provides basic information ascertaining promising solvents for the recovery.•Some organic solvents are effective to recovery ionic liquid and obtain lignin.•The effective order is ...isopropanol>ethanol>acetonitrile>ally alcohol>methanol.
Sixteen solvents added in lignin–ionic liquid mixture provide four types of solubility characteristics. The distinct characteristics can be classified by considering solubility parameters including ET Scale, Kamlet–Taft parameters and solubility parameters. Group 1 solvent shows promising solvents for lignin–ionic liquid separation, contributing full dissolution of ionic liquid with lignin precipitation. Isopropanol, the most potential solvent has solubility properties as following normalized molar electronic transition energies (ETN)=0.57, hydrogen-bond acidity (α)=0.76 and Hildebrand solubility parameter (δT)=23.58. This study examines potential solvents for ionic recovery, provides simple method of separation and leads to the feasibility of using ionic liquids in industrial applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
The syntheses of a zwitterionic base‐stabilized digermadistannacyclobutadiene and tetragermacyclobutadiene supported by amidinates and low‐valent germanium amidinate substituents are described. The ...reaction of the amidinate GeI dimer, LGe:2 (1, L=PhC(NtBu)2), with two equivalents of the amidinate tin(II) chloride, LSnCl (2), and KC8 in tetrahydrofuran (THF) at room temperature afforded a mixture of the zwitterionic base‐stabilized digermadistannacyclobutadiene, L2Ge2Sn2L′2 (3; L′=LGe:), and the bis(amidinate) tin(II) compound, L2Sn: (4). Compound 3 can also be prepared by the reaction of 1 with LArSnCl (5, LAr=tBuC(NAr)2, Ar=2,6‐iPr2C6H3) in THF at room temperature. Moreover, the reaction of 1 with the “onio‐substituent transfer” reagent 4‐NMe2‐C5H4NSiMe3OTf (8) in THF and 4‐(N,N‐dimethylamino)pyridine (DMAP) at room temperature afforded a mixture of the zwitterionic base‐stabilized tetragermacyclobutadiene, L4Ge6 (9), the amidinium triflate, PhC(NHtBu)2OTf (10), and Me3SiSiMe3 (11). X‐ray structural data and theoretical studies show conclusively that compounds 3 and 9 have a planar and rhombic charge‐separated structure. They are also nonaromatic.
Heavy elements: Zwitterionic base‐stabilized digermadistannacyclobutadiene (1) and tetragermacyclobutadiene (2) were synthesized by simple procedures (see scheme). X‐ray structural data and theoretical studies show that these compounds have a planar and rhombic charge‐separated structure. They are also nonaromatic.
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•Methoxide and its decomposed intermediates systematically investigate by DFT.•Methoxide decomposition reaction on strained PdZn(100) surfaces was studied.•Expansive strain increases activity of ...methoxide CH and CO bond breaking process.
Density functional theory has been used to systematically investigate the adsorption of methoxide and its decomposed intermediates (i.e. H, O, CH3 and CH2O) as well as methoxide decomposition reaction on strained PdZn(100) surfaces. The reaction and activation energies of methoxide CH and CO bond breaking process showed that expansive strain increased the activity of the PdZn(100) surface toward methoxide decomposition, but reduced its selectivity.
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