The agglomeration of graphene sheets and undesired pore size distribution usually lead to unsatisfactory electrochemical properties of reduced graphene oxide (RGO) film electrodes. Herein, crumpled exfoliated graphene (EG) sheets are adopted as the microstructure-regulating agent to tune the morphology and micro-/mesopore amounts with the aim of increasing active surface sites and ion transportation paths in electrodes. With the optimum ratio between EG and GO, the resulting 75%-EG/RGO shows significantly improved specific gravimetric capacitance (Cs) and rate capability when compared with pure RGO electrodes in a symmetrical supercapacitor system. Moreover, when coupling the 75%-EG/RGO cathode with a Zn anode to form a Zn ion hybrid supercapacitor (ZHS), the 75%-EG/RGO exhibits a much higher Cs of 327.39 F g–1 at 0.1 A g–1 and can maintain 91.7% capacitance after 8000 cycles. Systematic ex situ X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) measurements reveal that the charge storage mechanism is based on both reversible physical adsorption and dual ion uptake. Furthermore, the quasi-solid-state flexible ZHS also presents high capacitive performance and can maintain ∼100% capacitance under various bending states, demonstrating potential application in wearable electronics. This strategy opens up a new path for constructing high-performance graphene film electrodes.
The characteristics of fuel-cell type and chromatographic type online monitoring systems for dissolved gasses in oil are compared.The advantages and disadvantage of two online monitoring systems are given.
Organic matters, especially low molecular (LMW) ones, contribute to the serious membrane fouling, but the traditional coagulants cannot efficiently remove LMW substances. Herein, the coagulation-ultrafiltration combined process (C-UF) was applied to the actual lake water treatment, and a novel polyaluminum titanium composite coagulant (PATC) was used as a pretreatment reagent for membrane fouling mitigation. The results indicated that PATC performed better to efficiently remove organic matters than polyaluminium chloride (PAC) and polytitanium chloride (PTC). Notably, PATC could effectively remove building blocks and LMW substances, particularly the protein-like fluorescent substances. The removal mechanism of LMW substances by PATC was mainly the adsorption of amorphous hydrolysates, rather than the charge neutralization of positively charged hydroxy complexes. No matter with or without the cake layer, the control performance of the three coagulants on membrane fouling was consistent with their removal efficiency of organics. It indicated that although the cake layer played an important role in the interception of organics and small particles, it was not the decisive factor in lightning membrane fouling. Improving the removal efficiency of organic substances, especially the LMW component, is the key to alleviate membrane fouling. This work provides a new insight into the effects of the composite coagulant on the removal of various organics and the control of membrane pollution in actual lake water treatment.
This dataset contains the data underlying the following publication: Li Wen-Tao, Cao Meng-Jie, Young Tessora, Ruffino Barbara, Dodd Michael, Li Ai-Min, Korshin Gregory. (2017). Application of UV absorbance and fluorescence indicators to assess the formation of biodegradable dissolved organic carbon and bromate during ozonation. Water Research 2017, 111, 154-162. http://dx.doi.org/10.1016/j.watres.2017.01.009.
Catalytic enantioselection usually depends on differences in steric interactions between prochiral substrates and a chiral catalyst. We have discovered a carbene Si-H insertion in which the enantioselectivity depends primarily on the electronic characteristics of the carbene substrate, and the log(er) values are linearly related to Hammett parameters. A new class of chiral tetraphosphate dirhodium catalysts was developed; it shows excellent activity and enantioselectivity for the insertion of diarylcarbenes into the Si-H bond of silanes. Computational and mechanistic studies show how the electronic differences between the two aryls of the carbene lead to differences in energies of the diastereomeric transition states. This study provides a new strategy for asymmetric catalysis exploiting the electronic properties of the substrates.
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