Photo-thermal CO_(2) reduction with methane on group Ⅷ metals:In situ reduced WO_(3) support for enhanced catalytic activity

Photo-thermal CO_(2) reduction with methane(CRM)is beneficial for solar energy harvesting and energy storage.The search for efficient photo-thermal catalysts is of great significance.Here,we reveal that group Ⅷ metal catalysts supported by optical material WO_(3) are more effective for photo-thermal CRM,giving catalytic activities with visible light assistance that are 1.4-2.4 times higher than that achieved under thermal conditions.The activity enhancement(1.4-2.4 times)was comparable to that achieved with plasmonic-Au-promoted catalysts(1.7 times).Characterization results indicated that WO_(3) was partially reduced to WO_(3-x) in situ under the reductive CRM reaction atmosphere,and that WO_(3-x) rather than WO_(3) enhanced the activities with visible light assistance.Our method provides a promising approach for improving the activity of catalysts under light irradiation.

Catalytic decomposition of CH_4 over Ni-Al_2O_3-SiO_2 catalysts:Influence of pretreatment conditions for the production of H_2

This article reports the production of COx free hydrogen and carbon nanofibers by the catalytic decomposition of methane over Ni-Al2O3-SiO2 catalysts. The influence of reaction temperature, pretreatment temperature, and effect of reductive pretreatment on the decomposition of methane activity is investigated. The physico-chemical characteristics of fresh and deactivated samples were characterized using BET-SA, XRD, TPR, SEM/TEM, CHNS analyses and correlated with the methane decomposition results obtained. The Ni-Al-Si （4 ： 0.5 ： 1.5） catalyst reduced with hydrazine hydrate produced better H2 yields of ca. 1815 mol H2/mol Ni than the catalyst reduced with 5% H2/N2.

Investigate of in situ sludge reduction in sequencing batch biofilm reactor:Performances,mechanisms and comparison of different carriers

Biofilm is an effective simultaneous denitrification and in situ sludge reduction system,and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction.In this study,the performance and mechanism of in situ sludge reduction were compared between FSC-SBBR and SC-SBBR with constructed by composite floating spherical carriers(FSC)and multi-faceted polyethylene suspension carriers(SC),respectively.The variation of EPS concentration indicated that the biofilm formation of FSC was faster than SC.Compared with SCSBBR,the FSC-SBBR yielded 0.16 g MLSS/g COD,almost 27.27%less sludge.The average removal rates of COD and NH_(4)^(+)-N were 93.39% and 96.66%,respectively,which were 5.21% and 1.43% higher than the average removal rate of SC-SBBR.Investigation of the mechanisms of sludge reduction revealed that,energy uncoupling metabolism and sludge decay were the main factors for sludge reduction inducing 43.13%and 49.65%less sludge,respectively,in FSC-SBBR.EEM fluorescence spectroscopy and SUVA analysis showed that the hydrolytic capacity of biofilm attached in FSC was stronger than those of SC,and the hydrolysis of EPS released more DOM contributed to lysis-cryptic growth metabolism.In additional,Bacteroidetes and Mizugakiibacter associated with sludge reduction were the dominant phylum and genus in FCS-SBBR.Thus,the effect of simultaneous in situ sludge reduction and pollutant removal in FSC-SBBR was better.

Walnut-inspired microsized porous silicon/graphene core-shell composites for high-performance lithium-ion battery anodes

Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide （P-Si/rGO） core-shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh-g-1 at a current density of 1,000 mA-g-1, 1,600 mAh.g-1 at 2,000 mA-g-1, 1,500 mAh-g 1 at 3,000 mA-g-1, 1,200 mAh-g-1 at 4,000 mA.g-1, and 950 mAh.g~ at 5,000 mA.g-~, and maintain a value of 1,258 mAh.g-~ after 300 cycles at a current density of 1,000 mA-g 1. Their excellent rate performance and cycling stability can be attributed to the unique structural design： 1） The graphene shell dramatically improves the conductivity and stabilizes the solid- electrolyte interface layers; 2） the inner porous structure supplies sufficient space for silicon expansion; 3） the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.

Heterostructure Ag@WO3-x Composites with High Selectivity for Breaking Azo-bond

The heterostructure Ag@WO3-x（x=0.1 or 1） composites with high selectivity for breaking azo-bond were obtained by in situ reduction of Ag2WO4. The crystal structure and morphology of Ag@WO3-x were characterized by X-ray powder diffraction（XRD）, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The residue solution of methyl orange（MO） after degradation was tested by gas chromatograph mass spectrometer （GCMS） to analyze the exact components. The results indicate that the products after degradation are N,N-dimethylaniline, N,N-dimethyl-p-phenylenediamine and sulfanilic acid. This is caused by specific breaking of azo-bond in MO. The azo-bond breaking of MO by Ag@WO3-x could occur in dark without any light illumination. Therefore, we proposed a possible mechanism for this azo-bond breaking reaction based on the reaction condition and results.

一种原位还原策略用于构筑无枝晶锌负极

结合了三维结构和亲锌物种的集流体构筑策略被认为是构建高稳定锌金属负极的有效方法.然而,高昂的成本和复杂的制备工艺阻碍了其实际应用.本文通过在有均匀Cu^(2+)锚定的碳布集流体(ACC-600@Cu^(2+))上沉积锌,合理设计了一种稳定的三维锌金属复合阳极(Zn@ACC-600@Cu^(2+)).在锌成核过程中,Cu^(2+)原位还原为金属Cu,然后随着锌的进一步沉积,碳布表面逐渐形成均匀的亲锌的Cu-Zn合金界面层.密度泛函理论计算和实验观察表明,Cu-Zn合金界面不仅可以作为锌离子的亲锌沉积点,而且可以提高导电率,使电场和锌离子通量均匀化.因此,ACC-600@Cu^(2+)集流体可以实现高的镀锌/剥离可逆性,并在15.8 mV的极化电压下稳定循环410 h以上.作为概念验证,我们组装的Zn@ACC-600@Cu^(2+)‖MnO_(2)全电池具有良好的电池倍率性能,与原始碳布相比,其比容量显著提高至110 mA h g^(-1).本文提出的原位还原策略为三维锌金属复合负极的设计提供了一种简便且低成本的方法,促进了无枝晶和高稳定锌金属电池的发展.

Uniformly grown PtCo-modified C03O4 nanosheets as a highly efficient catalyst for sodium borohydride electrooxidation

A facile hydrothermal synthetic method, followed by in situ reduction and galvanic replacement processes, is used to prepare PtCo-modified Co304 nanosheets （PtCo/C0304 NSs） supported on Ni foam. The prepared nanomaterial is used as an electrocatalyst for NaBH4 oxidation in alkaline solution. The morphology and phase composition of PtCo/C0304 NSs are characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）. The catalytic performance of PtCo/Co3O4 NSs is investigated by cyclic voltammetry （CV） and chronoamperometry （CA） in a standard three-electrode system. Current densities of 70 and 850 mA·cm^-2 were obtained at -0.4 V for Co/Co3O4 and PtCo/Co3O4 NSs, respectively, in a solution containing 2 mol·L^-1 NaOH and 0.2 mol·L^-1 NaBH4. The use of a noble metal （Pt） greatly enhances the catalytic activity of the transition metal （Co） and Co3O4. Besides, both Co and Co3O4 exhibit good B-H bond breaking ability （in NaBH4）, which leads to better electrocatalytic activity and stability of PtCo/Co3O4 NSs in NaBH4 electrooxidation compared to pure Pt. The results demonstrate that the as-prepared PtCo/Co3O4 NSs can be a promising electrocatalyst for borohydride oxidation.