Hongping Li

One-pot extraction combined with metal-free photochemical aerobic oxidative desulfurization in deep eutectic solvent

Five low-cost deep eutectic solvents (DESs) were synthesized based on choline chloride (ChCl) and a series of straight-chain monobasic acids. Under UV light irradiation, one-pot extraction combined with the metal-free photochemical aerobic oxidative deep desulfurization of fuels in deep eutectic solvents was successfully achieved. This liquid-liquid extraction and photochemical oxidative desulfurization system (EPODS) comprised of air, isobutylaldehyde (IBA), DESs and model oil. The factors influencing sulfur removal were systematically investigated, including the amount of DES, volume ratio of model oil and IBA, different sulfur concentrations, different substrates and fuel composition. The sulfur removal of dibenzothiphene (DBT) could reach 98.6% with air as oxidizing agent under UV light irradiation. Sulfur removal by different sulfur compounds decreased as BT > DBT > 4,6-DMDBT. The possible photochemical oxidative desulfurization mechanism was researched by gas chromatograph-mass spectrometer (GC-MS), electron spin-resonance (ESR) spectroscopy and density functional theory (DFT).

Few-layered graphene-like boron nitride induced a remarkable adsorption capacity for dibenzothiophene in fuels

Metal-free graphene-like boron nitride (BN) samples were prepared and applied as adsorbents for removing dibenzothiophene (DBT) in model oil. The results showed that the graphene-like BN exhibited a remarkable adsorption performance. The adsorption capacity could reach 28.17 mg S g−1 adsorbent. Experiments have been carried out to investigate the effects of the number of BN layers, DBT initial concentration, and temperature on DBT adsorption. Langmuir and Freundlich isotherm models were used to study the adsorption of DBT on BN. The kinetic results showed that the adsorption process was best described by the pseudo-second-order kinetic model. Density functional theory (DFT) was employed to prove that the Lewis acid–base interaction plays an important role in removing DBT over graphene-like BN.

Controllable synthesis of Bi4O5Br2 ultrathin nanosheets for photocatalytic removal of ciprofloxacin and mechanism insight

A novel Bi4O5Br2 photocatalyst was prepared via a reactable ionic liquids-assisted solvothermal method accompanied with facile pH control. A Bi4O5Br2 ultrathin nanosheets material with 8 nm thickness could be obtained. The photocatalytic activity of the Bi4O5Br2 ultrathin nanosheets was evaluated with respect to the photo-degradation of colourless antibiotic agent ciprofloxacin (CIP) under visible light irradiation. The results revealed that the Bi-rich Bi4O5Br2 ultrathin nanosheets exhibited higher photocatalytic activity than BiOBr ultrathin nanosheets for the photo-degradation of CIP. The O2˙− anion was determined to be the main active species for the photo-degradation process by ESR. After multiple characterizations, the variable energy band structure was confirmed to be responsible for the enhanced photocatalytic activity. The more negative conduction band (CB) value of Bi4O5Br2 facilitated the formation of more active species, O2˙−. The upshifting of the CB and the wider valence band favor the higher separation efficiency of electron–hole pairs. It was hoped that this architecture of ultrathin 2D inorganic materials with a suitable band gap can be extended to other systems for high-performance photocatalysis applications.

Carbon-doped porous boron nitride: metal-free adsorbents for sulfur removal from fuels

Novel carbon-doped porous boron nitride (C-BN) has been successfully prepared by using 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) as a soft template and the carbon source via calcination under N2 atmosphere. Multiple techniques were applied to investigate the structure, morphology, and adsorptive desulfurization performance. The metal-free porous C-BN displayed enhanced adsorption performance for dibenzothiophene (DBT) than pure BN materials and exhibited one of the highest adsorption capacities reported up to now (49.75 mg S g−1 adsorbent according to the Langmuir isotherm model, 35.2 mg S g−1 adsorbent for 500 ppm sulfur model oil). After three times recycling, the adsorption capacity slightly decreased from 35.2 to 27.2 mg S g−1 adsorbent. The excellent adsorption performance of porous C-BN was attributed to the more exposed atoms along the edges of the pores and the stronger Lewis acid–base interactions between DBT and carbon-doped porous BN. Moreover, it is believed that this strategy to control the structure and composition of BN can be extended to incorporate other heteroatoms and control the pore size for BN materials by changing the anion or cation of the ionic liquids.

Electrical conductivity optimization in electrolyte-free fuel cells by single-component Ce0.8Sm0.2O2-δ–Li0.15Ni0.45Zn0.4 layer

Single-component electrolyte-free fuel cells possess a similar function to the traditional fuel cells with a complex three-component structure. However, how to enhance their electrical properties for practical industrial applications remains a timely and important issue. Here, we report the manipulation of concentration ratios of ionic to electronic conductors in an electrolyte-free Ce0.8Sm0.2O2-δ–Li0.15Ni0.45Zn0.4 by adjusting the relative weight between its two inside compositions. Our systematic investigations reveal that the fuel cell with 30% in weight of Li0.15Ni0.45Zn0.4 exhibits an almost uniform distribution of the two compositions and has a total conductivity as high as 10 × 10−2 S cm−1 at 600 °C. Such an enhancement is found to be attributed to the established balance between the numbers of its inside ionic and electronic conductors. These findings are relevant for the technological improvement of this new species of electrolyte-free fuel cell and represent an important step toward commercialization of this single-component fuel cell.

Controlled Gas Exfoliation of Boron Nitride into Few‐Layered Nanosheets

The controlled exfoliation of hexagonal boron nitride (h-BN) into single- or few-layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h-BN. Here, we present an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) using a novel gas exfoliation of bulk h-BN in liquid N2 (L-N2 ). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with a high mass yield of 16-20 %. N2 sorption and desorption isotherms show that the BNNS-10 exhibited a much higher specific surface area of 278 m(2)  g(-1) than that of bulk BN (10 m(2)  g(-1) ). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently, the L-N2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N2 , further peeling off h-BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields.

Supported ionic liquid [Bmim]FeCl4/Am TiO2 as an efficient catalyst for the catalytic oxidative desulfurization of fuels

High activity oxidation of sulfur compounds to sulfones in extraction coupled with catalytic oxidative desulfurization (ECODS) system catalyzed by supported ionic liquid [Bmim]FeCl4/Am TiO2 was reported. The catalysts were analyzed by thermogravimetric (TG) analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). It was found that [Bmim]FeCl4 and Am TiO2 had a synergistic effect on the desulfurization system. Effects of calcination temperature of the catalyst and various reaction conditions on the catalytic activity of desulfurization were investigated. Moreover, GC-MS analyses were employed to prove the process of the desulfurization. As a solid catalyst, the supported ionic liquid could be separated from the reaction easily. The recycling tests showed that the desulfurization efficiency remained 100% after reusing it for 25 times. Therefore, the ECODS system has excellent reusability and is promising for industrial applications for catalytic oxidative desulfurization.

Magnetic g-C3N4/NiFe2O4 hybrids with enhanced photocatalytic activity

Composite photocatalysts have attracted considerable attention in the exploration of both highly efficient and low cost materials. In this study, novel magnetic g-C3N4/NiFe2O4 photocatalysts were fabricated by a facile chemisorption method. X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) were utilized to analyze the structure and properties of samples, which indicated that NiFe2O4 had been integrated onto the surface of g-C3N4 successfully. The as-prepared 7.5% g-C3N4/NiFe2O4, with the best photocatalytic activity, can maintain high photocatalytic activity and stability after five runs in the presence of hydrogen peroxide under visible light irradiation. During the catalytic reaction, the synergistic effect between g-C3N4 and NiFe2O4 can accelerate photogenerated charge separation and facilitate the photo-Fenton process to get an enhanced photocatalytic activity. Moreover, the collection and recycling of photocatalyst was readily achieved owing to the distinctive magnetism of g-C3N4/NiFe2O4.

An in situ photoelectroreduction approach to fabricate Bi/BiOCl heterostructure photocathodes: understanding the role of Bi metal for solar water splitting

This paper presents for the first time a novel method of depositing plasmonic Bi nanoparticles on BiOCl nanosheets (Bi/BiOCl) via insitu photoelectroreduction, and Bi/BiOCl as the photocathode enabled solar water splitting in a TiO2–Bi/BiOCl photoelectrochemical (PEC) system. It is one of the challenges to understand the relationship between the PEC performance and the composite ratio of Bi/BiOCl, and the density functional theory calculation results show that charges obviously transfer from the Bi cluster to the BiOCl (001) surface. The structure of Bi/BiOCl photocathode has been successfully optimized, according to the current–potential curves and charge injection efficiency. The highly enhanced PEC activity could be attributed to the dual roles of Bi nanoparticles in enhancing the charge transfer and surface plasmon resonance (SPR) effect. More importantly, the optimal Bi/BiOCl photocathode achieved a solar hydrogen evolution rate of 2.4 µmol h−1 under full spectrum illumination (100 mW cm−2).

Preparation of magnetic Ag/AgCl/CoFe2O4 composites with high photocatalytic and antibacterial ability

Novel plasmonic photocatalysts, Ag/AgCl/CoFe2O4, were prepared via a two-step synthesis method. The obtained Ag/AgCl/CoFe2O4 composites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible absorption spectroscopy (UV-vis). The magnetic properties of the samples were studied by vibrating sample magnetometer (VSM) analysis. Methyl orange (MO), bisphenol A (BPA) and ciprofloxacin (CIP) were used as target pollutants to investigate the degradation capability of Ag/AgCl/CoFe2O4. Results showed that the composite can degrade both colored and colorless pollutants, while Ag/AgCl/CoFe2O4 (3 : 1) composite showed the highest photoactivity in the degradation of MO. It can degrade about 93.38% MO in 1.5 h. The reactive species scavenger results indicated that hydroxyl radicals (˙OH) were not the main photooxidant, while holes (h+) and superoxide anion radicals (˙O2−) played key roles in MO decoloration. Furthermore, the degraded solution of BPA was analyzed using high performance liquid chromatography (HPLC). The results showed that BPA was decomposed gradually. The composite was magnetically separated and investigated using three successive recycle experiments under visible light. The results exhibited that the photoactivity of Ag/AgCl/CoFe2O4 is stable. Besides, Ag/AgCl/CoFe2O4 also exhibited good antibacterial activity against Escherichia coli (E. coli). The method used to prepare the composite can be expanded and applied to synthesize other magnetically separable photocatalysts.