WO3-x as an activation medium to prompt overall water splitting of NiFe-based electrocatalyst.

The efficient oxygen evolution reaction (OER) is crucial for various electrochemical processes, especially for overall water splitting (OWS). In this study, we focus on the utilization of WO3-x as an activation medium to enhance the OER performance of NiFe-based electrocatalysts. Firstly, we synthesize WO3-x nanowires supported on nickel foam (NF) and then incorporate NiFe on WO3-x nanowires by a simple hydrothermal method. The WO3-x self-supported NiFe (Oxy)hydroxide (denoted as NiFe-W-O/NF) shows a three-dimensional stereostructure composed of ultrathin nanosheets (∼ 4.0 nm). This unique structure provides a large open surface for fuller diffusion of the electrolyte while exposing more active sites. The electronic interaction of tri-centers of NiFeW accelerates the surface reconstruction process of γ-NiOOH and FeOOH, which are converted into the main active species in a short time. The electrochemical measurements confirm that the NiFe-W-O/NF has low OER overpotentials (233 mV at 10 mA cm-2, 298 mV at 100 mA cm-2) and excellent stability (100 h in total) in 1 M KOH electrolyte. In addition, the NiFe-W-O/NF || NiFe-W-O/NF battery also exhibits a low cell voltage (1.52 V at 10 mA cm-2) with a stable lifetime (50 h) under alkaline conditions. These results highlight the great potential of NiFe-W-O/NF for practical applications.

An optimization strategy for photo-Fenton-like catalysts: Based on crystal plane engineering of BiVO4 and electron transfer properties of 0D CQDs.

Herein, we report a novel Cu2(OH)3 F/CQDs-BiVO4 composite photo-Fenton-like system, which used BiVO4 and Cu2(OH)3F as electron donor and acceptor, respectively, and achieved efficient electron transfer between them through the electron bridging effect of Carbon quantum dots (CQDs). The material exhibited excellent ciprofloxacin (CIP) removal efficiency in the photo-Fenton-like coupled system. Cu2(OH)3 F/CQDs-BiVO4 had an incredibly fast response rate, eliminating 98.1% of CIP from the solution in just 1 h, according to the reaction kinetics. Exploratory tests proved that the catalyst kept up a sufficient level of activity across a wide pH range of 3-11 and in the presence of various anions. The activity, morphology, and crystal structure of the samples did not appreciably alter after five recycles. Finally, a possible reaction mechanism was also proposed based on the band structure, position and reaction species.

Formic acid assisted fabrication of Oxygen-doped Rod-like carbon nitride with improved photocatalytic hydrogen evolution.

Rod-like carbon nitrides synthesized by calcinating supramolecular precursors prepared from acid (or alkali) and melamine have attracted great attention because they have large surface area and abundant accessible active sites. However, they are highly inefficient in separating charges, which limits their photocatalytic activity. Here, we prepared porous, rod-shaped carbon nitrides doped with oxygen by calcinating the precursors prepared from melamine and formic acid. The porous O-doped g-C3N4 nanorods have a large surface area of 81.4 m2 g-1. In particular, the oxygen doped into the catalyst enables it to have high efficiency in utilizing light in a range of 420-600 nm, and significantly improves its ability to separate photogenerated carriers. Under light irradiation (λ ≥ 420 nm), the prepared catalyst exhibits high photocatalytic activity with a hydrogen production rate of 12,766 µmol g-1h-1, which is 18.3 times that of pure carbon nitride. This research provides a novel way of preparing highly active non-metallic photocatalysts.

Which kind of nitrogen chemical states doped carbon dots loaded by g-C3N4 is the best for photocatalytic hydrogen production.

Recently, g-C3N4 (CN) loaded N-doped carbon dots (NCDs) have been widely studied as promising metal-free photocatalysts due to their impressive performance in hydrogen production. However, deep understanding of the effect of nitrogen chemical states on photocatalytic activity is still lacked. In this work, NCDs doped with pyrrole nitrogen, graphite/pyrrole nitrogen, and pyrrole/pyridine nitrogen were prepared and hybridized with g-C3N4. The characterizations revealed that, incorporation of pyrrole N-doped CDs into g-C3N4 (CN/NCDs-en) effectively enhanced the visible light absorption, facilitated electron-hole separation, and promoted the participation of photoexcited electrons in H2 evolution reaction. Moreover, theoretical calculation showed that, compared with graphite N and pyridine N, pyrrole N has the most appropriate H adsorption ability, which is conducive to the H2 formation. Under visible light irradiation, the CN/NCDs-en exhibited the best hydrogen evolution of 3028 µmol h-1 g-1. These results shed a light on the design and optimization of N-doped metal-free photocatalysts for H2 evolution reaction.

Ultrahigh Adsorption Capacity and Kinetics of Vertically Oriented Mesoporous Coatings for Removal of Organic Pollutants.

Highly efficient removal of organic pollutants currently is a main worldwide concern in water treatment, and highly challenging. Here, vertically oriented mesoporous coatings (MCs) with tunable surface properties and pore sizes have been developed via the single-micelle directing assembly strategy, which show good adsorption performances toward a wide range of organic pollutants. The micelle size and structure can be precisely regulated by oil molecules based on their n-octanol/water partition coefficients (Log P) in the oil-water diphase assembly system, which are critical to the pore size and pore surface property of the MCs. The affinity and steric effects of the MCs can be on-demand adjusted, as a result, the MCs show a ultrahigh adsorption capacity (263 mg g-1 ), surface occupancy ratio (≈41.92%), and adsorption rate (≈10.85 mg g-1  min-1 ) for microcystin-LR, which is among the best performances up to date. The MCs also show an excellent universality to remove organic pollutants with different properties. Moreover, overcoming the challenges proposed by particulate absorbents, the MCs are stable and can be easily regenerated and reused without secondary contamination. This work paves a new route to the synthesis of high-quality MCs for water purification.

Facile Synthesis of Water-Stable Multicolor Carbonized Polymer Dots from a Single Unconjugated Glucose for Engineering White Light-Emitting Diodes with a High Color Rendering Index.

Tunable emission carbonized polymer dots (CPDs) are highly desirable for the preparation of optoelectronic devices, especially white light-emitting diodes (WLEDs). In most available studies, polychromatic CPDs are synthesized using aromatic molecules as precursors. However, few studies report the successful synthesis of polychromatic CPDs using two or more unconjugated precursors. In this work, we prepare multicolor fluorescent CPDs from a single unconjugated precursor, glucose, via a hydrothermal reaction. By controlling the particle size and degree of graphitization of the synthesized CPDs, their emission wavelength can be tuned in the range 440-625 nm (i.e., almost the entire visible region). Furthermore, the CPDs can be used to construct LEDs of varying colors, including WLEDs (CIE coordinates: 0.34, 0.36) with the correlated color temperature and color rendering index of 4997 K and 92.69, respectively. In brief, the strategy proposed in this study successfully converts unconjugated glucose into high-performance LEDs with great application potential.

Pd Anchored on a Phytic Acid/Thiourea Polymer as a Highly Active and Stable Catalyst for the Reduction of Nitroarene.

A kind of N, P, C, O-containing polymer was easily prepared via microwave heating of phytic acid and thiourea just for 90 s. After impregnation and reduction of H2PdCl4, highly dispersed Pd single atoms/sub-nano clusters loaded on the phytic acid/thiourea polymer (Pd-CNSP) were successfully obtained. Owing to the synergetic effect of the polymer support and Pd, the catalyst Pd-CNSP achieves a great atomic efficiency of Pd species and exhibits an outstanding catalytic ability in the reduction of 4-nitrophenol. The k value of the catalyst Pd-CNSP (2.17 min-1 mg-1) is about 19 times higher than that of the commercial Pd/C (5 wt %) catalyst. The turnover frequency value is as high as 848 min-1, which is the highest value reported so far. Pd-CNSP also has good selectivity for the reduction of halogen-substituted (Cl and Br) nitroaromatics. It is expected to be mass-produced and used in other industrial hydrogenation reactions.

Photocatalytic reduction of Cr (VI) on nano-sized red phosphorus under visible light irradiation.

Red phosphorus as a novel visible-light-responsive and metal-free photocatalyst has attracted extensive attention in the area of energy conversion and environmental remediation. Herein, nano-sized red phosphorus photocatalyst was synthesized via a hydrothermal and ultrasonic method and used for reduction of Cr (VI) for the first time. The as-prepared photocatalysts were characterized by XRD, UV-Vis-DRS, XPS, SEM, TEM and photoelectrochemical measurements. Compared to bulk red phosphorus, nano-sized red phosphorus exhibit a significantly enhanced photocatalytic activity for reduction of Cr (VI) due to the greatly reduced charge transfer resistance and enhanced adsorption capability of Cr (VI).

Two-step catalytic hydrodeoxygenation of fast pyrolysis oil to hydrocarbon liquid fuels.

Two-step catalytic hydrodeoxygenation (HDO) of fast pyrolysis oil was investigated for translating pyrolysis oil to transportation grade hydrocarbon liquid fuels. At the first mild HDO step, various organic solvents were employed to promote HDO of bio-oil to overcome coke formation using noble catalyst (Ru/C) under mild conditions (300 °C, 10 MPa). At the second deep HDO step, conventional hydrogenation setup and catalyst (NiMo/Al2O3) were used under severe conditions (400 °C, 13 MPa) for obtaining hydrocarbon fuel. Results show that the phenomenon of coke formation is effectively eliminated, and the properties of products have been significantly improved, such as oxygen content decreases from 48 to 0.5 wt% and high heating value increases from 17 to 46 MJ kg(-1). GC-MS analysis indicates that the final products include C11-C27 aliphatic hydrocarbons and aromatic hydrocarbons. In short, the fast pyrolysis oils were successfully translated to hydrocarbon liquid fuels using a two-step catalytic HDO process.

Carbon materials for chemical capacitive energy storage.

Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

Direct triblock-copolymer-templating synthesis of ordered nitrogen-containing mesoporous polymers.

Ordered nitrogen-containing mesoporous carbonaceous polymers have been synthesized via a direct triblock-copolymer-templating process by using soluble, low-molecular-weight urea-phenol-formaldehyde (UPF) resin as an organic precursor and amphiphilic triblock copolymer Pluronic F127 as a template. Characterization using small-angle X-ray scattering (SAXS), N(2) sorption, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TG), Fourier transform infrared (FTIR), and water adsorption techniques reveals that the obtained nitrogen-containing mesoporous polymers possess ordered structures, high surface areas (385-420 m(2)/g), large pore sizes (3.1-3.6nm) and pore volumes (0.25-0.44cm(3)/g), and high nitrogen content (2.69-2.94%). Various mesostructures, such as two-dimensional (2-D) hexagonal (space group, p6mm) and 3-D body-centered cubic (Im3 m) symmetries, can be obtained by simply adjusting the mass ratio of UPF/F127. The content of nitrogen in the mesoporous polymers can also be easy varied by changing the amount of urea and the reaction time of UPF resin precursors. Compared with the nitrogen-free mesoporous polymer, the obtained mesoporous carbonaceous polymers show a more hydrophilic nature and thus evidently higher water adsorption capacity. The presence of nitrogen groups can also significantly improve the adsorption performance of Fe(III) ions.

Encapsulation of polyaniline in 3-D interconnected mesopores of silica KIT-6.

Composite material PANI/KIT-6, with polyaniline (PANI) chains encapsulated in the 3-D interconnected pore channels of mesoporous silica, KIT-6, has been synthesized via a gas-phase method. The composite formation and the presence of PANI inside the pore channels of KIT-6 were evidenced by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), small-angle X-ray scatter (SAXS), transmission electron microscopy (TEM), and N(2) adsorption-desorption isotherms. The PANI/KIT-6 composite showed good electrical conductivity (2.4x10(-3) S/cm) due to the formation of 3-D networks of PANI inside the 3-D interconnected channels of KIT-6. The resistance of PANI/KIT-6 composite at different relative humidities (RH) was investigated. An essentially linear relationship between the relative resistance of the composite and the relative humidity of the environment was found from 11.3% to 97.3% RH.

Periodic mesoporous organosilicas: a type of hybrid support for water-mediated reactions.

Hybrid mesoporous periodic organosilicas (Ph-PMOs) with phenylene moieties embedded inside the silica matrix were used as a heterogeneous catalyst for the Ullmann coupling reaction in water. XRD, N2 sorption, TEM, and solid-state NMR spectroscopy reveal that mesoporous Ph-PMO supports and Pd/Ph-PMO catalysts have highly ordered 2D hexagonal mesostructures and covalently bonded organic-inorganic (all Si atoms bonded with carbon) hybrid frameworks. In the Ullmann coupling reaction of iodobenzene in water, the yield of biphenyl was 94%, 34%, 74% and for palladium-supported Ph-PMO, pure silica (MCM-41), and phenyl-group-modified Ph-MCM-41 catalysts, respectively. The selectivity toward biphenyl reached 91% for the coupling of boromobenzene on the Pd/Ph-PMO catalyst. This value is much higher than that for Pd/Ph-MCM-41 (19%) and Pd/MCM-41 (0%), although the conversion of bromobenzene for these two catalysts is similar to that for Pd/Ph-PMO. The large difference in selectivity can be attributed to surface hydrophobicity, which was evaluated by the adsorption isotherms of water and toluene. Ph-PMO has the most hydrophobic surface, and in turn selectively adsorbs the reactant haloaryls from aqueous solution. Water transfer inside the mesochannels is thus restricted, and the coupling reaction of bromobenzene is improved.