Ji Yang

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

Conversion of inert cryptomelane-type manganese oxide into a highly efficient oxygen evolution catalyst via limited Ir doping

The oxygen evolution reaction (OER) is a critical half reaction for energy storage techniques and is regarded as a major challenge due to its sluggish kinetics and complex reaction mechanism. The traditional OER catalysts, such as IrO2, RuO2 and their binary or ternary oxides, have finite large-scale commercial applications due to their significant cost and rareness. Here, we hydrothermally synthesized cry-Ir by doping Ir into non-OER active cryptomelane-type manganese oxide to significantly reduce the Ir mass ratio by 60.3% from 85.7% in IrO2 to 34% in the developed catalyst, along with higher OER performance with a lower onset potential and 10 times higher specific mass activity. The special tunnel structure of cryptomelane plays an important role in promoting its OER activity through facilitating water molecular insertion into the tunnel. We combined Raman, XPS and TEM mapping to confirm that no IrO2 composite is present on the cry-Ir surface. The XPS and XAS spectra indicate substitution of Ir4+ on the Mn3+ site and the presence of more 5d states in the Ir site compared to IrO2. The differences in VBS spectra between cry-Ir, IrO2 and cry-Mn indicate that the electronic structure of Ir sites is modified when Ir substitutes Mn3+ sites. Thus, this special tunnel structure and modified Ir electronic structure in cry-Ir are responsible for the outstanding OER performance. Our studies provide an approach for designing effective Ir-based OER catalysts whilst significantly reducing the consumption of precious elements.

OER activity manipulated by IrO6 coordination geometry: an insight from pyrochlore iridates.

The anodic reaction of oxygen evolution reaction (OER), an important point for electrolysis, however, remains the obstacle due to its complicated reaction at electrochemical interfaces. Iridium oxide (IrO2) is the only currently known 5d transition metal oxide possessing admirable OER activity. Tremendous efforts have been carried out to enhance the activity of iridium oxides. Unfortunately there lies a gap in understanding what factors responsible for the activity in doped IrO2 or the novel crystal structure. Based on two metallic pyrochlores (Bi2Ir2O7 and Pb2Ir2O6.5) and IrO2. It has been found that there exists a strong correlation between the specific OER activity and IrO6 coordination geometry. The more distortion in IrO6 geometry ascends the activity of Ir sites, and generates activity order of Pb-Ir > IrO2 > Bi-Ir. Our characterizations reveal that distorted IrO6 in Pb-Ir induces a disappearance of J = 1/2 subbands in valence band, while Bi-Ir and IrO2 resist this nature probe. The performed DFT calculations indicated the distortion in IrO6 geometry can optimize binding strength between Ir-5d and O-2p due to broader d band width. Based on this insight, enhancement in OER activity is obtained by effects that change IrO6 octahedral geometry through doping or utilizing structural manipulation with nature of distorted octahedral coordination.

Pt-Doped NiFe2O4 Spinel as a Highly Efficient Catalyst for H2 Selective Catalytic Reduction of NO at Room Temperature

H2 selective catalytic reduction (H2-SCR) has been proposed as a promising technology for controlling NOx emission because hydrogen is clean and does not emit greenhouse gases. We demonstrate that Pt doped into a nickel ferrite spinel structure can afford a high catalytic activity of H2-SCR. A superior NO conversion of 96% can be achieved by employing a novel NiFe1.95Pt0.05O4 spinel-type catalyst at 60 °C. This novel catalyst is different from traditional H2-SCR catalysts, which focus on the role of metallic Pt species and neglect the effect of oxidized Pt states in the reduction of NO. The obtained Raman and XPS spectra indicate that Pt in the spinel lattice has different valence states with Pt(2+) occupying the tetrahedral sites and Pt(4+) residing in the octahedral ones. These oxidation states of Pt enhance the back-donation process, and the lack of filling electrons of the 5d band causes Pt to more readily hybridize with the 5σ orbital of the NO molecule, especially for octahedral Pt(4+), which enhances the NO chemisorption on the Pt sites. We also performed DFT calculations to confirm the enhancement of adsorption of NO onto Pt sites when doped into the Ni-Fe spinel structure. The prepared Pt/Ni-Fe catalysts indicate that increasing the dispersity of Pt on the surfaces of the individual Ni-Fe spinel-type catalysts can efficiently promote the H2-SCR activity. Our demonstration provides new insight into designing advanced catalysts for H2-SCR.

Substituent effects on the aggregation-induced emission and two-photon absorption properties of triphenylamine–dibenzo[a,c]phenazine adducts

Exploration of high-performance fluorescent materials, especially those with two-photon absorption and aggregation-induced emission (AIE) properties, is of great significance to both fundamental research and practical applications. In the present work, a series of triphenylamine–dibenzo[a,c]phenazine adducts (Q1–Q5) with triphenylamine (TPA) moieties decorated by substituents ranging from nil to alkyl (methyl/octyl) and finally to alkoxy (methoxyl/octyloxy) groups were elaborately designed and facilely synthesized. Their photophysical properties including one- and two-photon absorption properties have been systematically investigated to clarify the relationships between their structures and properties and to see how a small change in the structure makes big differences in their performances. The proterotype triphenylamine–dibenzo[a,c]phenazine (TPA–DBP) adduct Q1 and the alkyl-substituted TPA–DBP adducts (Q2 and Q3) show intramolecular charge transfer (ICT) plus aggregation-enhanced emission (AEE) features while the alkoxy-decorated TPA–DBP adducts, i.e., Q4 and Q5, exhibit typical AIE behaviors. The differences in their photophysical properties can be mainly ascribed to the substituent effects, which are closely associated with the RIM (restriction of intramolecular motion) mechanism. Moreover, the AIE-active red luminogen Q5 with the largest two-photon absorption cross-section (σ = 801 GM) and high brightness has been further fabricated into nanoparticles via a simple and well-established method to satisfy the requirements of in vivo two-photon fluorescence imaging of blood vessels. The water-dispersible and biocompatible PEG-modified nanoparticles of Q5 performed well as an effective contrast agent for the visualization of blood vasculature with high signal-to-noise ratios, low photodamage and deep-tissue penetration capability (100 μm).

A red fluorescent turn-on chemosensor for Al3+ based on a dimethoxy triphenylamine benzothiadiazole derivative with aggregation-induced emission

Aluminum is a known neurotoxin to organisms and believed to cause Alzheimers disease, osteomalacia, and breast cancer. Therefore, effective tools for Al3+ recognition are in great demand. In this study, a new, sensitive, and highly selective red turn-on chemosensor (TB-COOH) for Al3+ was prepared by combining the dimethoxy triarylamine benzothiadiazole motif and carboxyl group, where the benzothiadiazole derivative functioned as an aggregation-induced emission (AIE) moiety and the carboxyl motif functioned as the recognition site for Al3+. This chemosensor showed significant fluorescence enhancement upon selective addition of Al3+ and a relatively low detection limit (1.5 × 10−7 M). The fluorescence turn-on mechanism was ascribed to the aggregation of TB-COOH after complexation with Al3+, which was confirmed by 1H NMR and FT-IR spectroscopies and scanning electronic microscopy. Furthermore, benefiting from its good water solubility and biocompatibility, imaging detection and real-time monitoring of Al3+ in living HeLa cells were successfully achieved.

Synthesis, two-photon absorption and aggregation-induced emission properties of multi-branched triphenylamine derivatives based on diketopyrrolopyrrole for bioimaging

In this work, three new diketopyrrolopyrrole (DPP)-based multi-branched derivatives (YJ-1, YJ-2 and YJ-3) with triphenylamine, 2,4,6-tri([1,1′-biphenyl]-4-yl)-1,3,5-triazine and 2,2′,2′′-(nitrilotr-is([1,1′-biphenyl]-4′,4-diyl))tris(3-phenylacrylonitrile) cores have been designed and synthesized. Their one- and two-photon absorption properties have been investigated. The two-photon absorption cross sections (σ) measured by the open aperture Z-scan technique are determined to be 2912, 2016 and 2800 GM for YJ-(1–3), respectively. This result indicates that donor–acceptor–donor (D–A–D)-type molecules are benefit to improve σ and their σ data increase with the better intramolecular charge transfer (ICT). Also, all of the three DPP derivatives exhibit good aggregation-induced emission (AIE) properties which are very weakly fluorescent in DMF, but a strong red fluorescent emission in solid state and in the aggregate state. More importantly, diketopyrrolopyrrole with tri-phenylamine (YJ-1) was applied for cell imaging and two-photon excited fluorescence in vivo imaging of mouse ear.

Circulating Regeneration and Resource Recovery of Flue Gas Desulfurization Residuals using a Membrane Electroreactor: From Lab Concept to Commercial Scale

Desulfurization residuals (using NaOH sorbent) were regenerated electrochemically, and at the same time sulfur in the flue gas was recovered as H(2)SO(4) and H(2) was produced as a clean energy. Since industrialization should always be the final goal to pursue for lab technologies and the evolution of pilot- and full-scale commercial reactors has taken place relatively slowly, this paper is aimed to develop an electroreactor on a sufficiently large scale to evaluate the application potential of the proposed regeneration process. The following key design parameters are discussed: (1) voltage distributions over electrode, membrane, and electrolyte; and (2) scaling up correlation based on lab-scale reactor operation parameters. Thereafter, in the developed reactor, the desulfurization residuals using NaOH sorbent from a semidry flue gas desulfurization (FGD) facility of a power plant in Shandong Province were regenerated and it is significant to note that the electrochemical efficiency of the designed reactor is comparable to that of the chlor-alkali industry, showing that the technology is environmentally friendly and economically feasible. If this technology is to be employed for FGD, the facility could be a profit-generating manufacturing part instead of a currently money-consuming burden for the plants.

Development and field-scale optimization of a honeycomb zeolite rotor concentrator/recuperative oxidizer for the abatement of volatile organic carbons from semiconductor industry.

The combined concentrator/oxidizer system has been proposed as an effective physical-chemical option and proven to be a viable solution that enables Volatile Organic Carbons (VOCs) emitters to comply with the regulations. In this work, a field scale honeycomb zeolite rotor concentrator combined with a recuperative oxidizer was developed and applied for the treatment of the VOC waste gas. The research shows the following: (1) for the adsorption rotor, zeolite is a more appropriate material than Granular Activated Carbon (GAC). The designing and operation parameters of the concentrator were discussed in detail including the size and the optimal rotation speed of rotor. Also the developed rotor performances was evaluated in the field; (2) Direct Fired Thermal Oxidizer (DFTO), Recuperative Oxidizer (RO), Regenerative Thermal Oxidizer (RTO) and Regenerative Catalytic oxidizer (RCO) are the available incinerators and the RO was selected as the oxidizer in this work; (3) The overall performance of the developed rotor/oxidizer was explored in a field scale under varying conditions; (4) The energy saving strategy was fulfilled by reducing heat loss from the oxidizer and recovering heat from the exhaust gas. Data shows that the developed rotor/oxidizer could remove over 95% VOCs with reasonable cost and this could be helpful for similar plants when considering VOC abatement.

Electro-thermal treatment of high concentration ammonia in water by gaseous oxidation in liquid phase (GOLP)

Gaseous oxidation in liquid phase (GOLP) process was proposed to degrade high concentration ammonium in water. The innovative concept behind the reactor design is that the monocrystalline silicon chip coated with catalyst could be heated instantaneously by direct current, which will gasify the surrounding ammonium solution and later catalytically convert it to harmless N(2). It is found out that Co(3)O(4) instead of Co(2)O(3) is the active catalytic component in the GOLP process and it coats the silicon chip evenly with nut-shell particle. The experimental results reveal that the GOLP process could degrade high concentration NH(4)(+) efficiently, in which when the current was 10A, the reactor could remove almost 98% NH(4)(+) after 2h treatment, at the initial concentration 1810mgL(-1). The overall GOLP process for de-nitrification could be presumed to have two steps: (1) the gasification of liquid around catalyst; and (2) catalytic conversion of NH(4)(+) to N(2), which is experimentally demonstrated by Ion Chromatography data. Also, the influences of current and pH were investigated to optimize the operating parameters for the GOLP reactor, and the preliminary energy consumption analysis based on lab data was provided for future reference. These results show that the GOLP process will be able to sustain without extra energy input theoretically if the ammonia concentration is higher than 1.48%.