Bamboo-like nitrogen-doped carbon supported chlorine-doped Fe2P as an antibacterial oxygen reduction catalyst.

Bio-inspiration and biomimetics offer guidance for designing and synthesizing advanced catalysts for the oxygen reduction reaction (ORR) in microbial fuel cells (MFCs). Herein, a chlorine-doped Fe2P supported by nitrogen-doped carbon (Cl-Fe2P/NC) catalyst was designed and prepared based on imitating the bamboo structure. The electronegative chlorine captured the electron transfer from Fe2P and transferred it to NC through carbon nanotubes (CNTs). The antibacterial chlorine inhibited the cathode biofilm formation to enhance the ion transport. Cl-Fe2P/NC achieved a half-wave potential of 0.91 V and an onset potential of 0.99 V versus a reversible hydrogen electrode. After 500 h of reaction, the MFCs assembled by the Cl-Fe2P/NC cathode achieved a maximum power density of 1505 mW m-2. This work provides insights into the design of advanced materials through bio-inspiration and biomimicry.

Bimetallic CoSn nanoparticles anchored on N-doped carbon as antibacterial oxygen reduction catalysts for microbial fuel cells.

Sluggish oxygen reduction reaction (ORR) kinetics and biofilm formation limit the power generation and stability of microbial fuel cells (MFCs). Herein, bimetallic CoSn nanoparticles anchored on ZIF-derived N-doped carbon (CoSn@NC) were designed and synthesized as bifunctional catalysts to accelerate the ORR and improve the antibacterial activity. Sn modulated the electronic structure of bimetallic CoSn by drawing electrons from Co. Electron redistribution of CoSn@NC optimized the O2 adsorption at Co sites for rapid ORR kinetics. The up-shifted d-band center of Co sites reduced the energy barrier of the rate-determining step for *O formation, resulting in efficient catalytic activity. Bimetallic CoSn nanoparticles were beneficial for the four-electron transfer process for more ˙OH species production. Sn2+ and ˙OH synergistically improved the antibacterial activity of CoSn@NC to inhibit the growth of the cathode biofilm and accelerate mass-charge transfer. CoSn@NC demonstrated superior oxygen reduction activity with a half-wave potential of 0.84 V and an onset potential of 0.90 V, respectively. The MFCs assembled with the CoSn@NC cathodic catalyst exhibited an excellent power density of 1380 mW m-2 and long-term stability for 105 h. This work provides a strategy for the design of antibacterial ORR catalysts for improved catalytic activity and long-term stability.

Electron transfer and surface activity of NiCoP-wrapped MXene: cathodic catalysts for the oxygen reduction reaction.

NiCoP constructed on a conductive substrate can achieve efficient oxygen reduction reaction (ORR) catalytic activity. Herein, we report the in-situ growth of NiCoP on the surface of an MXene nanosheet (MXene@NiCoP). The MXene nanosheet accelerated the electron transfer and enhanced the surface activity of the NiCoP. Density functional theory calculations indicated that MXene@NiCoP possessed the advantages of a low overpotential and high OH* adsorption energy in the ORR process. MXene@NiCoP proved to be a highly active catalyst for the ORR with a half-wave potential of 0.71 V vs. RHE. The assembled single-chamber air-cathode microbial fuel cell obtained high electricity generation performance.

Fe, N, S co-doped cellulose paper carbon fibers as an air-cathode catalyst for microbial fuel cells.

The heteroatoms and transition metal co-doped carbon-based catalysts are an important way to improve the catalytic activity of oxygen reduction reaction (ORR). Herein, we reported a facile method to obtain iron, nitrogen, and sulfur co-doped cellulose paper carbon fibers as catalysts (Fe-N-S/CFs) for ORR in microbial fuel cells (MFCs) with the adsorption recovery of Congo red molecules from dye wastewater. The thermal treatment promoted the etching of carbon surface by ferric ions, resulting in increased surface roughness for forming the defective carbon structure. The rich active species and defective carbon formed on the etched surface to enhance the electroactive surface area and effective sites. Fe-N-S/CFs catalysts achieved high half-wave potential due to the synergy effect between chemical components and defect structures. The assembled single-chamber air cathode MFC gained a high maximum power density of 1773 ± 40 mW m-2 versus Pt/C MFC of 1325 ± 94 mW m-2. This work provides a strategy for recovering dye molecules from wastewater to prepare non-precious metal catalysts for enhancing ORR activity.

Properties of flame-retardant leaf fiber cement-based composites at high temperatures.

Flame retardant modification of leaf fibers was carried out to solve the technical problem of poor fire resistance of plant fibers and improve the utilization rate of urban fallen leaves in building materials. The modification scheme adopts three flame retardants, i.e., ammonium polyphosphate (APP), magnesium hydroxide (MH), and aluminum hydroxide (ATH), and two covering layers, i.e., pure acrylic polymer lotion and water glass (Na2O · nSiO2) solution. The modified leaf fiber's combustion behavior and pyrolysis properties were tested and analyzed. The physical and mechanical characteristics, as well as the thermal insulation qualities, of leaf fiber cement-based composites (LFCC) were studied at high temperatures. The findings revealed that the three flame retardants had an effect on the chemical structure of leaf fibers. In comparison to leaf fibers without flame-retardant modification, flame-retardant-modified leaf fibers have a much greater thermal stability. and its LOI is greater than 27.0%, which is a fire-retardant material. Except for the sample with water glass as the modified cover layer, at high temperatures, the composite flame-retardant fiber LFCC's mass-loss rate is lower compared with fibers without flame-retardant modification or fibers modified with only one kind of flame-retardant. In the composite flame-retardant modified fiber LFCC, the samples with better strength at high temperature are those with ATH replacing 30% and 50% MH. The thermal conductivity of LFCC is negatively correlated with the range of temperature change.

Electrolyte additive induced fast-charge/slow-discharge process: Potassium ferricyanide and potassium persulfate for CoO-based supercapacitors.

The electrolyte additives of potassium ferricyanide and potassium persulfate can ensure that CoO-supercapacitors achieve a fast charge/slow discharge and long cycling stability. The redox couple of Fe(CN)63-/Fe(CN)64- can induce S2O82- to produce the sulfate radical ( [Formula: see text] ). Strong oxidizing species, including S2O82-, Fe(CN)63- and [Formula: see text] , can accelerate oxidation of the CoO electrode surface from Co2+ to Co3+ in the charge process. The additives can achieve a good synergistic effect on accelerating CoO oxidation during the charge process. In a three-electrode cell, a CoO electrode with electrolyte additives achieves a fast-charge and slow-discharge time of 939 s and 1699 s at a current density of 1 A g-1, respectively. The capacitance retention can be maintained at 84.5% after 10,000 cycles at a current density of 5 A g-1. As a supercapacitor, the device can achieve a fast-charge and slow-discharge time of 156 s and 191 s at a current density of 1 A g-1, respectively. The capacitance retention can be maintained at 85.5% after 10,000 cycles at a current density of 5 A g-1.

Hydrogen peroxide-induced growth of hierarchical Ni3S2 nanorod/sheet arrays for high performance supercapacitors.

The rational design and simple synthesis of high performance electrodes are important aspects of energy storage fields. However, it is difficult to determine a facile preparation method to obtain hierarchical Ni3S2 nanorod/sheet arrays. Herein, hydrogen peroxide-induced growth by the hydrothermal method is used to fabricate the hierarchical Ni3S2 nanorod/sheet arrays on nickel foam substrates. Hydrogen peroxide can accelerate the hydrolysis of Na2S2O3 to release sulfur ions and then induce formation of the hierarchical nanorod/sheet. The one-dimensional nanorod skeleton acting as high-speed electron transfer channels can support the nanosheets. The two-dimensional nanosheets can provide abundant active edge sites and protect the backbone from electrochemical corrosion. The hierarchical structure integrates the advantages of sufficient active sites, effective protection and high-speed electron transfer. The electrode based on the Ni3S2 nanorod/sheet delivers a high specific capacitance of 6.87 F cm-2 at 2 mV s-1 (6.24 F cm-2 at 5 mA cm-2) and long cycling stability (85.7% capacitance retention at 15 mA cm-2 after 3000 cycles). The asymmetric supercapacitor gains a high energy density of 1.16 mWh cm-3 at 15.00 W cm-3. The hierarchical Ni3S2 nanorod/sheet arrays are expected to be candidates for the electrodes of practical supercapacitors.

Removal of the heavy metal ion nickel (II) via an adsorption method using flower globular magnesium hydroxide.

To remove toxic Ni(II) ions from wastewater, a novel flower globular magnesium hydroxide (FGMH) was prepared by a gentle method using trisodium citrate as a crystal modifier. This material exhibited a high specific surface area. The synthesized products and adsorption mechanism for Ni(II) ions were examined by diverse characterization technologies and methods. FGMH was employed to remove Ni(II) ions by the adsorption method. The effects of various parameters, viz., the amount of adsorbent, contact time, temperature and pH, on the removal rate by the adsorbent were investigated in detail. The kinetic data fitted well with a pseudo-second-order model and experimental equilibrium adsorption data conformed to a Langmuir isotherm under optimized conditions. The optimal process parameters included 30 mg of FGMH, a 50 min contact time, pH values between 6.07 and 7.71 for the Ni(II) solution, and adsorption at room temperature for 50 mL of 80 mg/L Ni(II) solution. The percentage of removal efficiency was found to be above 92.64%, and the maximum adsorption capacity of MH was 287.11 mg/g under optimum adsorption conditions. The analyses indicated that the Ni(II) ions were chemisorbed on the FGMH surface.

[Present situation of congenital defects in five counties (cities) of Gansu province in 2009 - 2010].

OBJECTIVE: To understand the situation of congenital defects' in five counties/cities in Gansu province so as to provide scientific evidence for the development of effective interventions. METHODS: General information was collected on all the neonates who were born in Dunhuang city, Jingchuan county, Hui county, Weiyuan county and Yongjing county in Gansu province between Oct. 1(st), 2009 to Sep. 30(th), 2010, with all of their gestational age above 28 weeks. Neonates would include live birth, dead fetus and still birth. RESULTS: The overall incidence of congenital defects was 7.49‰ in the five counties/cities in Gansu province in 2009. Ranking order in the top three showed as congenital heart disease, pigmented nevus and limb deformity. Disease with the highest mortality was congenital heart disease (0.79‰). The incidence of congenital defects was 8.35‰ in 2010 with the ranking order of the top three as congenital heart disease, neural tube defects/pigmented nevus and hydrocephalus. Diseases having the highest mortality was congenital heart disease (1.10‰). Different incidence rates on congenital defects were seen in related areas, with the highest incidence as 14.65‰ in Dunhuang city. Hui county had the lowest incidence-3.28‰. CONCLUSION: Different incidence of congenital defects were seen in respective areas in Gansu province, with the change of ranking orders. Different strategies should be developed differently depending on the current states of congenital defects in respective areas, according to the three-grade prevention model, to reduce the occurrence of congenital defects.