Immobilization of Oxyanions on the Reconstructed Heterostructure Evolved from a Bimetallic Oxysulfide for the Promotion of Oxygen Evolution Reaction

Efficient and durable oxygen evolution reaction(OER)requires the electrocatalyst to bear abundant active sites,optimized electronic structure as well as robust component and mechanical stability.Herein,a bimetallic lanthanum-nickel oxysulfide with rich oxygen vacancies based on the La_(2)O_(2)S prototype is fabricated as a binder-free precatalyst for alkaline OER.The combination of advanced in situ and ex situ characterizations with theoretical calculation uncovers the synergistic effect among La,Ni,O,and S species during OER,which assures the adsorption and stabilization of the oxyanion SO_(4)^(2-)onto the surface of the deeply reconstructed porous heterostructure composed of confining Ni OOH nanodomains by La(OH)_3 barrier.Such coupling,confinement,porosity and immobilization enable notable improvement in active site accessibility,phase stability,mass diffusion capability and the intrinsic Gibbs free energy of oxygen-containing intermediates.The optimized electrocatalyst delivers exceptional alkaline OER activity and durability,outperforming most of the Ni-based benchmark OER electrocatalysts.

Adsorption and Post Adsorption Behavior of Schwertmannite with Various Oxyanions

The adsorption and post adsorption behavior of schwertmannite with various oxyanions were investigated for clean-up contaminated water with hazardous oxyanions and safe disposal of spent schwertmannite. The result of adsorption experiments showed that the maximum capacities of oxyanions adsorption onto schwertmannite are 1.023, 0.934, 0.723 and 0.313 mmol/g for arsenate, phosphate, chromate and selenate, respectively. Based on the differences in the adsorption capacities, the selectivity of oxyanion adsorption on schwertmannite decreases as the order: arsenate ≥ phosphate > chromate >> selenate. Change in the Zeta potential after adsorption by arsenate, phosphate and chromate were very different from those after adsorption by selenate and of the original schwertmannite. This difference implies that the adsorption mechanism on schwertmannite with arsenate, phosphate and chromate is different from that with selenate and sulfate. Arsenate, phosphate, and chromate ions form inner-sphere complexes with the surface of schwertmannite, while selenate and sulfate ions form outer-sphere complexes with the surface of schwertmannite. Based on a comparison with anion adsorption, strong base anions form inner-sphere complexes, which induce a strong adsorption with schwertmannite as well as it is conducive to high adsorption capacity. From the results of aging experiments, schwertmannite with sulfate and selenate changed to a more stable phase, goethite, in a short time, whereas there is no change in the XRD patterns of schwertmannite with arsenate and phosphate after 30 days. The stability of schwertmannite after the adsorption increased in the following order: sulfate ≌ selenate «chromate ≌ arsenate. The solubility of schwertmannite with different oxyanions was calculated according to solid solution theory. The solubility of schwertmannite decreased after adsorption of oxyanions with high selectivity. It is concluded that oxyanions with high selectivity can stabilize schwertmannite by decreasing the solubility of the schwertmannite after adsorption of the oxyanions.

High-performance Bi_(2)S_(3)/ZnO photoanode enabled by interfacial engineering with oxyanion for efficient photoelectrochemical water oxidation

In the present contribution,we demonstrate that the sluggish kinetics of oxygen evolution reaction(OER)over the bismuth sulfide(Bi_(2)S_(3))photoanode,which severely restricts its photoelectrochemical activity,is markedly accelerated by employing a sulfatecontaining electrolyte.First-principle calculation points to the spontaneous adsorption of sulfate(SO_(4)^(2−))on Bi_(2)S_(3)and its capacity of stabilizing the OER intermediates through hydrogen bonding,which is further reinforced by increasing the local density of states near the Fermi level of Bi_(2)S_(3).Meanwhile,the electron transfer is also promoted to synergistically render the ratedetermining step(from O*to OOH*)of OER over Bi_(2)S_(3)kinetically facile.Last but not least,benefitting from such enhanced OER activity and efficient charge separation resulted from depositing Bi_(2)S_(3)on the zinc oxide nanorods(ZnO NRs),forming a core–shell heterojunction,its photocurrent density achieves 8.61 mA·cm^(−2)at 1.23 VRHE,far surpassing those reported for additional Bi_(2)S_(3)-based and several state-of-the-art photoanodes in the literature and further exceeding their theoretical limit.The great promise of the Bi_(2)S_(3)/ZnO NRs is in view of such outperformance,the superior Faradaic yield of oxygen of more than~80%and the outstanding half-cell applied bias photon-to-current efficiency of~1%well corroborated.

Combining material characterization with single and multi-oxyanion adsorption for mechanistic study of chromate removal by cationic hydrogel

Cationic hydrogel with magnetic property was synthesized via radical polymerization and its removal capacity of chromate from contaminated water was found to be 200 mg/g.Using Fourier transform infrared spectroscopy（FT-IR） study,the mechanism of chromate removal by hydrogel was found to be non-specific adsorption,mainly due to ion exchange,as evidenced by the positively charged functional group,trimethyl ammonium-N＋（CH3）3,in the monomer.Verifications were accordingly determined by testing di？erent oxyanion adsorption onto the hydrogel.The results of the chromate adsorption experiments illustrated that the amount of chromate adsorbed was nearly equal to that of the chloride released from the hydrogel,which is part of the evidence for ion exchange.Single and multi-oxyanion adsorption experiments were also performed,and it was demonstrated that ion removal was species independent,but charge dependent,another characteristic of the ion exchange process.It was found that the same Langmuir model can be applied to best fit the findings of single and multi-oxyanion adsorption,which further indicates the mechanism of chromate removal is attributed to ion exchange.In view of the above,the background anions compete for adsorption sites with chromate,evidenced by inhibitive chromate removal in the presence of background electrolytes in the batch studies,further echoing the ion exchange mechanism.

Zwitterionic glycine modified Fe/Mg-layered double hydroxides for highly selective and efficient removal of oxyanions from polluted water

Zwitterionic glycine was employed to modify Fe/Mg-layered double hydroxides(LDH)to realize an GFe/Mg-LDH adsorbent with high adsorption capacities of oxygen-containing anions including As(Ⅴ),P(Ⅴ)and Cr(Ⅵ).When the Fe/Mg mole ratio was 0.02 mol/0.02 mol,the G-Fe/Mg-LDH has a good adsorption performance.The optimum adsorption pH value of G-Fe/Mg-LDH for oxygen-containing anions was 6.The selectivity of three oxygen-containing anions was Cr(Ⅵ)

SYNTHESIS OF pH-RESPONSIVE AMPHIPHILIC DIBLOCK COPOLYMERS CONTAINING POLYISOBUTYLENE via OXYANION-INITIATED POLYMERIZATION AND THEIR MULTIPLE SELF-ASSEMBLY MORPHOLOGIES

Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-（N,N- dimethylamino）ethyl methaerylate] （PIB-b-PDMAEMA） and polyisobutylene-block-poly（metharylic acid） （PIB-b-PMAA）, were synthesized via oxyanion-initiated polymerization, and their multiple self-assembly behaviors have been studied. An exo-01efin-terminated highly reactive polyisobutylene （HRPIB） was first changed to hydroxyl-terminated PIB （PIB-OH） via hydroboration-oxidation of C =C double bond in the chain end, and then reacted with KH to yield a potassium alcoholate of PIB （PIB-O-K＋）. PIB-O-K＋ was immediately used as a macroinitiator to polymerize DMAEMA monomer, resulting in a cationic diblock copolymer PIB-b-PDMAEMA. With the similar synthesis procedure, the anionic diblock copolymer PIB-b- PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate （tBMA） and subsequent hydrolysis of tert-butyl ester groups in PtBMA block. The functional PIB and block copolymers have been fully characterized by 1H-NMR, FT-IR spectroscopy, and gel permeation chromatography （GPC）. These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent. Transmission electron microscopy （TEM） images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles, vesicles with different particle sizes and cylindrical aggregates, depending on various factors including block copolymer composition, solvent polarity and pH value.

Synthesis of novel tempera-ture/pH responsive polymer via oxyanionic polymerization

Hyperbranched poly(3-ethyl-3-oxetanemetha-nol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-g-DMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyper-branched poly(3-ethyi-3-oxetanemethanol) (HP) reacted with KH and conversed into potassium alcoholate macroinitiators with high initiating efficiencies. High monomer conversion (】95%) was obtained and no residual macroinitiators or monomer was observed. UV-visible spectra indicate that the aqueous solution of the HP-g-DMA exhibited the lowermost critical solution temperature (LCST). The LCST was influ-enced by the chain length of DMA and pH condition of solu-tion. It is found that LCST decreased with increasing DMA chain length or increasing pH value of solution.

硒是双刃剑?——谈微生物中的硒代谢

硒位于元素周期表第Ⅵ主族,是一种生命必需的微量元素,是第21位氨基酸硒代半胱氨酸、硒代甲硫氨酸和含硒酶的必需组分。硒在人体免疫系统、抗癌、抗氧化等方面发挥重要作用,缺硒会导致40种以上的疾病。硒以Se(-Ⅱ)、Se(0)、Se(+Ⅳ)和Se(+Ⅵ)4种价态存在,所有价态间的转化都有微生物的参与。本文主要综述最近几年国内外微生物代谢硒的研究进展,包括硒对生命体的重要作用与机制,硒的化学性质与生物地球化学循环,硒的氧化、还原和甲基化等多样的代谢硒的微生物类群,微生物代谢硒的分子机制;并探讨了微生物代谢硒在未来的关注点和实际应用。阐明微生物代谢硒在生物地球化学循环、生物多样性、植物富硒、人类健康和环境污染治理等方面都发挥着重要作用。

冶金电化学对埋弧焊接过程中氧迁移的影响

对五种自制焊剂进行了正反极性的埋弧焊接,利用LECO氧分析仪测定熔滴的含氧量。结果表明：直流正接条件下熔滴的含氧量明显高于直流反接,且这一趋势随着熔渣碱度的增大而增大,间接证明了焊接电弧阴极和阳极熔渣/液态金属界面存在冶金电化学作用。进一步分析显示,在焊接参数一定的条件下,熔渣中氧离子浓度是影响熔滴阶段金属电化学增氧的关键因素。

MMA-DMAEMA两亲嵌段共聚物的合成

在室温下,采用苄醇钾(BzOK)作引发剂通过氧阴离子聚合方法合成了相对分子质量、嵌段组成均可控且相对分子质量分布窄的两亲嵌段共聚物BzO-MMA-DMAEMA和BzO-MMA-DMAEMA.用1HNMR、FTIR、GPC对共聚物进行表征.比较不同加料次序所获得的嵌段共聚物,发现相同'单体/引发剂'条件下,共聚物的组成完全一致,从而证明MMA和DMAEMA的氧阴离子聚合反应体系均为活性聚合.

Engineering catalytic efficiency of thermophilic lipase from <i>Geobacillus zalihae</i>by hydrophobic residue mutation near the catalytic pocket

In-silico and experimental investigations were conducted to explore the effects of substituting hydrophobic residues;Val, Met, Leu, Ile, Trp and Phe into the oxyanion Q114 of T1 lipase. We hypothesized that the oxyanion Q114, involved in substrate binding is also associated with modulation of conformational stability and in conferring specific enzyme attributes. The insilico investigations accurately predicted the quality of the protein packing in some of the variants. Our study found by altering the hydrophobicity of the oxyanion 114, remarkably altered enzyme conformational stability and catalytic attributes. Substitution with Leu resulted improvements in four out of the six tested characteristics. The hydrophobic Leu might have improved local structure folding and increased hydrophobic interactions with other residues in the vicinity of the mutation. The Met variant showed higher activity over the wild-type in hydrolyzing a wider range of natural oils. The bulky amino acids, Phe and Trp negatively affected T1 lipase and resulted in the largest disruption of protein stability and inferior enzyme characteristics. We have successfully illustrated that a single point residue changes at oxyanion 114 could result in a myriad of enzyme attributes, which implied there was some interplay between hydrophobicity and conformation for lipase catalytic functions.

含氧酸盐熔盐Raman光谱V_(1)峰位移的解释

若干含氧酸盐熔盐Raman光谱表明:含氧酸根离子的v_(1)峰(对称伸缩振动散射)位置随阳离子不同而异,James在解释NO_(3)^(-)在熔盐中的Raman光谱时,认为正电场较强的阳离子可能使NO_(3)^(-)中N—O键电子云密度增加,从而使力常数增大,v_(1)峰频率上升。为了探讨这一观点是否正确以及它对其它含氧酸根离子是否适用,我们用EHMO方法计算了若干由碱金属离子Me+和含氧酸根离子XOmm-(包括NO_(3)^(-)、NO_(2)^(-)、IO_(3)^(-)等)组成的原子簇(Me+)x(XOnm-)中的X—O键的重叠集居数和原子净电荷,并考察其与相应的熔盐的Raman光谱v_(1)峰位置的关系。以探讨v_(1)峰位移的物理实质。

催化剂对基团转移聚合的影响

本文研究了催化剂的种类和用量对硅烯醚型引发剂引发的基团转移聚合的影响。发现四丁基二苯甲酸氢铵(Bu_4NH(C_6H_5CO_2)_2,TBABB)和HsI_2的催化效果较好。只需引发剂的4％的HgI_2即可使MMA的基团转移聚合达到完全转化。认为有效的氧负离子催化剂应由较稳定的铵正离子和电负性较大的氧负离子所组成。过量的催化剂不利于基团转移聚合的进行。考察了TBABB催化剂对温度的依赖性及其浓度对聚合速率,分子量和分子量分布,转化率的影响。

微生物中氧化态硒还原酶的研究进展

微生物还原氧化态硒对于硒在自然界的循环有重要作用,目前发现的还原方式主要有三种,即硒酸盐/亚硒酸盐经甲基转移酶或谷胱甘肽(GSH)作用后成为可挥发性的甲基硒化物;在细胞内的与含巯基的化合物发生化学反应,生成硒中间产物,进入各种代谢途径,或被巯基还原酶还原为Se0;反硝化细菌内硝酸还原酶具有还原氧化态硒的功能,发现另一种氧化态硒还原酶可以专门地还原氧化态硒为低价态或单质,该酶被发现同属于Ⅱ型钼酶家族。本文综述了氧化态硒还原酶的研究进展,以及在生化、遗传、基因组和蛋白质组学等方法研究中的应用。

Role of amino acid residues involved in the active cavity of proline iminopeptidase in catalytic activity

The proline iminopeptidase (PchPiPA) of the white-rot fungi Phanerochaete chrysosporium is an exopeptidase specific to catalyze hydrolysis of the N-terminal proline of peptides or proteins. Its catalytic cavity is comprised of a catalytic triad (Ser107, Asp264 and His292) and an oxyanion hole (His38, Gly39, Gly40 and Pro41). In this work, several amino acid residues involved in the catalytic cavity were selected for investigation of their influences on the catalytic activity by site-directed mutagenesis. It was shown that mutation of residues (Gly39 and Gly40) involved in oxyanion hole resulted in almost complete loss of catalytic activity largely due to changes in kcat. The other residues (Gly42 and Cys45) lined at the entrance of the active cavity also yielded a profound negative effect on the activity. Mutation of the other two residues Arg130 and Gly131 which were flanked spatially by the nucleophilic attacking active site of Ser107, caused different effects on the activity. R130Aincreased catalytic efficiency due to changes in both kcat and Km;while G131V decreased the value of kcat/Km mainly due to changes in kcat. And T111Aalso caused a negative effect on the kcat. Conclusively, these amino acid residues involved in active cavity were more susceptible to be negatively affected by mutation, suggested that the active cavity of proline iminopeptidase might evolve to be less plausible.

铁、锰和铝氧化物吸附硒的行为研究

表生环境中,吸附是硒进入固相沉积环境的重要途径之一。为了厘清硒氧阴离子团吸附行为及其影响因素,本文选择赤铁矿、二氧化锰和氧化铝作为吸附剂,采用批次实验的方法,研究了溶液pH、硒浓度以及反应时间等对硒的吸附影响。结果表明:为了达到较理想的吸附效果,溶液的pH应控制在4~6之间,在室温、pH为5时,赤铁矿、二氧化锰和氧化铝对亚硒酸盐的饱和吸附量分别约为1.62×10-3、0.33×10-3和1.07×10-3,对硒酸盐的饱和吸附量分别约为1.0×10-3、0、0.55×10-3;其吸附规律均符合Langmuir等温吸附方程,且理论最大吸附量与实验得出的最大吸附量基本一致。运用准一级动力学、准二级动力学、Elvoich方程和颗粒内扩散模型4种动力学模型对实验数据进行拟合,发现硒吸附过程运用准二级动力学方程表示时相关性最好,表明了硒氧阴离子团在铁、锰、铝氧化物表面的吸附过程较为复杂,可能涉及表面物理吸附和颗粒扩散等过程。

通过自缩合乙烯基氧阴离子聚合制备超支化聚甲基丙烯酸羟丙酯

由甲基丙烯酸羟丙酯通过自缩合乙烯基氧阴离子聚合(self-condensingvinyloxyanionicpolymerization)制备了端羟基的超支化聚甲基丙烯酸酯.以氢化钾(KH)和冠醚的复合物为引发剂时,可以得到高分子量的聚合物.用1HNMR和13CNMR谱图证实了聚合物的超支化结构.由于在聚合过程中存在质子转移反应,引发剂与单体的摩尔比会影响所得聚合物的结构.超支化聚合物的玻璃化转变温度在58.1～81.4℃之间,且随着引发剂与单体的比例的减小而降低.当引发剂与单体等摩尔比时,所得聚合物的支化度为0.49.

氧阴离子引发甲基丙烯酸-2-(N,N-二甲氨基)乙酯聚合制备Y型大分子单体

A novel well-defined water-soluble macromonomer based on 2-(dimethylamino) ethyl methacry-late(DMAEMA) was synthesized by using functional initiators such as potassium alcoholate of trimethylol-propane allyl ether via oxyanion-initiated polymerization. GPC and 1H NMR studies confirmed that themacromonomers had narrow molecular weight distribution and each Poly(DMAEMA) chain contained apolymerizable allyl group. The macromonomers were highly surface active in aqueous media. They havepotential applications in preparation of surface-clean and functional latexes both as effective stabilizers andas co-monomers.

Mg,N共掺改性木质素对废水中As(Ⅴ)的高选择性吸附研究

分别以三乙烯四胺(TETA)和MgCl_(2)为氮源和Mg^(2+)源,通过N元素掺杂和Mg^(2+)修饰,制备了一种新型木质素基吸附剂。N掺杂木质素(N-Lignin)对As(Ⅴ)具有一定的选择性,Mg^(2+)修饰后(Mg@N-Lignin)进一步增强了该选择性。Mg@N-Lignin表现出良好的再生性能。Mg@N-Lignin对As(Ⅴ)的吸附等温线和动力学遵循Langmuir等温线模型和拟二阶动力学模型。Mg@N-Lignin对As(Ⅴ)的饱和吸附量为687.46 mg/g,并在30 min内达到平衡。

甘氨酸修饰Fe/Zn层状双金属氢氧化物的制备及其吸附性能

层状双金属氢氧化物(LDH)由于其表面积大、热稳定性好等优点,在水中含氧阴离子去除领域的应用受到了广泛的关注.但由于相同电荷间的静电排斥作用,LDH对含氧阴离子的吸附效果较差,并且对特定含氧阴离子的选择性较差.为提高其吸附效果和选择性,制备了甘氨酸修饰的Fe/Zn-LDH(G-Fe/Zn-LDH).实验结果表明:在Fe和Zn物质的量比为1∶1的条件下,G-Fe/Zn-LDH-1对As(V)有很好的选择性,对As(V)的吸附遵循Langmuir等温线模型和拟二阶动力学模型,对As(V)的饱和吸附量达859.52 mg·g^(-1),并在60 min~120 min内达到吸附平衡;吸附As(V)后的G-Fe/Zn-LDH-1具有良好的再生性能,与第1次吸附/脱附循环相比,G-Fe/Zn-LDH-1在第5次吸附/脱附循环中对As(V)的吸附量下降了13.30%.本研究为污水中As(V)的选择性去除提供了一种新方法.