Pan-Pan Wang

Sulfurizing-Induced Hollowing of Co9S8 Microplates with Nanosheet Units for Highly Efficient Water Oxidation

Transition metal-based compounds are promising alternative nonprecious electrocatalysts for oxygen evolution to noble metals-based materials. Nanosheet-constructed hollow structures can efficiently promote the electrocatalystic activity, mainly because of their largely exposed active sites. Herein, hierarchical Co9S8 hollow microplates with nanosheet building units are fabricated via sulfurization and subsequent calcination of preformed Co-glycolate microplates. Benefiting from the advantages of a hollow structure, nanosheet units and high Co3+ content, Co9S8 hollow microplates exhibit remarkable catalytic property for oxygen evolution reaction (OER) with low overpotential of 278 mV to reach a current density of 10 mA cm-2, a low Tafel slope of 53 mV dec-1, and satisfied stability. This construction method of Co9S8 hierarchical hollow microplates composed of a nanosheet structure is an effective tactic for promoting OER performance of water splitting electrocatalysts.

Synthesis of self-stacked CuFe2O4–Fe2O3 porous nanosheets as a high performance Li-ion battery anode

Self-stacked CuFe2O4–Fe2O3 porous nanosheets were prepared via a facile polyol-mediated route followed by calcination. Because of its highly porous structures and good electrical and ion conductivity of the well-dispersed CuFe2O4 phase in the matrix, the hybrid material exhibits high specific capacity of 910 mA h g−1 at 0.5 C after 200 cycles, superior capacity retention (0.02% capacity loss per cycle) and good rate capability (417 mA h g−1 at 4 C) as a promising anode material for Li-ion batteries.

A core–shell fiber-constructed pH-responsive nanofibrous hydrogel membrane for efficient oil/water separation

In order to efficiently separate oil/water emulsions and enhance antifouling properties, a core–shell fiber-constructed pH-responsive nanofibrous hydrogel membrane (NHM) was successfully fabricated by a uniaxial electrospinning method. A simple thermal treatment stabilized the core–shell structure and enhanced the tensile stress of the NHMs. When immersed in water, the nanofibrous membrane exhibited a change to a transparent hydrogel membrane. The as-prepared NHMs possess superhydrophilic and underwater superoleophobic properties and can effectively separate various oil/water emulsions in acid, neutral or alkali environments, driven solely by gravity. Interestingly, the pH-responsive properties of the NHMs caused changes in the micromorphology of the nanofibers and the pore sizes of the membranes, which had great influences on the permeating flux (varying from 17 L m−2 h−1 to 1019 L m−2 h−1); moreover, there were no effects on separation performance. Due to their high flux, high separation efficiency (>99%) and excellent recyclability (TOC < 32 ppm after each cycle), these NHMs possess great potential for oily wastewater treatment and resource recycling.

In situ soft-chemistry synthesis of β-Na0.33V2O5 nanorods as high-performance cathode for lithium-ion batteries

β-Na0.33V2O5 nanorods were prepared via a facile soft-chemistry strategy using Na+ intercalated (NH4)0.5V2O5 nanosheets as precursor. Based on X-ray diffraction, Fourier transform infrared spectra and scanning electron microscope analysis, the formation mechanism of β-Na0.33V2O5 nanorods is proposed, which involves cation co-intercalation and crystal structure slip as well as a phase transformation process induced by cation release. When used as cathode for lithium-ion batteries, β-Na0.33V2O5 nanorods calcined at 600 °C exhibited good stable cycling behaviour with high capacity retention of 81.3% after 50 cycles. Reversible discharge capacities of 237.8, 199.8, 183.5, 151.7 mA h g−1 and 110.5 mA h g−1 can be delivered at 30, 60, 150, 300 and 600 mA g−1, respectively. It is expected that the Na0.33V2O5 nanorods could be employed as a promising cathode material in rechargeable lithium-ion batteries.

Development of a novel anoxic/oxic fed-batch membrane bioreactor (AFMBR) based on gravity-driven and partial aeration modes: A pilot scale study

A novel pilot gravity-driven anoxic/oxic fed-batch membrane bioreactor (AFMBR) was developed to treat real domestic wastewater. In this process, the anoxic and oxic stages created favorable conditions for stable and continuous nitritation-denitritation/denitrification-nitrification links without adding external carbon source. Excellent removals of organic carbon/nitrogen (NH4+-N: 71-97%, COD: 78-96%, UV254: 70-95%, TN: 20-60%) and spontaneous permeability recovery were achieved simultaneously. It was assessed at micro levels by characterizing sludge particle morphologies, microbiota functional evolutions, fouling layer properties and energy consumptions. It was demonstrated that the aerobic granular sludge (AGS) was cultivated successfully. Notable differences of microbial diversity were observed in different regions of AFMBR. The SEM and AFM spectra suggested the loose cake layers can shed automatically due to low pressure and continue flushing. The energy consumption in AFMBR was around 0.042 kWh/m3, far lower than that of conventional MBR. Overall, the AFMBR has a potential on improvement of domestic wastewater treatment.

4.5 Membrane Bioreactor Application in Water Treatment

Membrane bioreactor (MBR), with the characteristics of high-quality effluent and small footprint, is a new type of water treatment process combing biotreatment with membrane separation. MBR can be divided into three categories according to their configurations. Here, the design and operation of MBR are introduced. The main application of MBR is the domestic wastewater treatment; however, it is also an attractive option for the industrial wastewater treatment. In addition, the applications of MBR at polluted surface water supply have received more and more attentions.