A-Site Effect on the Conversion of Bio-Ethanol into Isobutene over Ternary A1ZnyZrzOn Catalysts

Ternary multifunctional A1ZnyZrzOn catalysts are prepared by introducing A-site transition metals with the redox capability into binary Zn1Zr8On. Structure and morphology were investigated by means of XRD, BET and FESEM, respectively. Activity data showed that Cr addition exhibited obvious beneficial effect to promote isobutene production from direct conversion of bio-ethanol compared to other A-site metal dopants. A significant higher yield of isobutene over Cr-promoted Zn1Zr8On catalyst was also observed with respect to its binary Zn1Zr8On counterpart. The choice of A-site metal is of prime importance in the isobutene production, catalyzing mainly the ethanol dehydrogenation, meanwhile the appropriate addition of zinc on the catalyst surface is also essential for good isobutene yield.

超薄氮掺杂碳纳米片负载单原子镍用于高效电催化还原二氧化碳

将二氧化碳转化为高附加值的燃料和化学品是缓解当前能源危机和控制温室气体排放的有效策略之一,但此法受限于缺乏高活性与高选择性的电催化剂。因此,我们通过热解含镍金属有机框架结构(MOF)和二氰二胺制得负载高含量镍单原子(7.77%(w))的超薄氮掺杂二维碳纳米片用于电催化还原CO_(2)生成CO。研究发现高温热解能将MOF中Ni^(2+)转化为Ni^(+)-N-C和Ni^(2+)-N-C结构,且Ni^(+)-N-C含量依赖于热解温度——其含量随热解温度增加呈现火山型变化。800℃下,Ni^(2+)到Ni^(+)-N-C的转化和石墨化的C生成达到最优水平。Ni^(+)-N-C结构有适宜的^(*)CO中间体结合能,能有效地抑制析氢反应的同时还能促进CO生成。因此,800℃热处理制得的材料(Ni-N-C-800)催化CO_(2)生成CO效率最高。调节电解液浓度,能进一步优化电催化性能。当电解液(碳酸氢钾)浓度为0.5 mol·L^(−1)时,Ni-N-C-800的CO生成选择性在较宽电压窗口内(−0.77到^(−1).07 V vs.RHE)都高于90%,且具有优良的稳定性。这些结果表明,选择合适的前躯体通过调控热解温度以及氮掺杂可以有效提高镍基MOF衍生催化剂的二氧化碳电催化性能。

FUS-mediated HypEVs: Neuroprotective effects against ischemic stroke

Few studies have investigated the properties and protein composition of small extracellular vesicles (sEVs) derived from neurons under hypoxic conditions. Presently, the extent of the involvement of these plentiful sEVs in the onset and progression of ischemic stroke remains an unresolved question. Our study systematically identified the characteristics of sEVs derived from neurons under hypoxic conditions (HypEVs) by physical characterization, sEV absorption, proteomics and transcriptomics analysis. The effects of HypEVs on neurites, cell survival, and neuron structure were assessed in vitro and in vivo by neural complexity tests, magnetic resonance imaging (MRI), Golgi staining, and Western blotting of synaptic plasticity-related proteins and apoptotic proteins. Knockdown of Fused in Sarcoma (FUS) small interfering RNA (siRNA) was used to validate FUS-mediated HypEV neuroprotection and mitochondrial mRNA release. Hypoxia promoted the secretion of sEVs, and HypEVs were more easily taken up and utilized by recipient cells. The MRI results illustrated that the cerebral infarction volume was reduced by 45% with the application of HypEVs, in comparison to the non- HypEV treatment group. Mechanistically, the FUS protein is necessary for the uptake and neuroprotection of HypEVs against ischemic stroke as well as carrying a large amount of mitochondrial mRNA in HypEVs. However, FUS knockdown attenuated the neuroprotective rescue capabilities of HypEVs. Our comprehensive dataset clearly illustrates that FUS-mediated HypEVs deliver exceptional neuroprotective effects against ischemic stroke, primarily through the maintenance of neurite integrity and the reduction of mitochondria-associated apoptosis.

An orientated mass transfer in Ni-Cu tandem nanofibers for highly selective reduction of CO_(2) to ethanol

Electrochemically reducing CO_(2)to ethanol is attractive but suffers from poor selectivity.Tandem catalysis that integrates the activation of CO_(2)to an intermediate using one active site and the subsequent formation of hydrocarbons on the other site offers a promising approach,where the control of the intermediate transfer between different catalytic sites is challenging.We propose an internally self-feeding mechanism that relies on the orientation of the mass transfer in a hierarchical structure and demonstrate it using a one-dimensional(1D)tandem core-shell catalyst.Specifically,the carbon-coated Ni-core(Ni/C)catalyzes the transformation of CO_(2)-to-CO,after which the CO intermediates are guided to diffuse to the carbon-coated Cu-shell(Cu/C)and experience the selective reduction to ethanol,realizing the orientated key intermediate transfer.Results show that the Faradaic efficiency for ethanol was 18.2%at-1 V vs.RHE(V_(RHE))for up to 100 h.The following mechanism study supports the hypothesis that the CO_(2)reduction on Ni/C generates CO,which is further reduced to ethanol on Cu/C sites.Density functional theory calculations suggest a combined effect of the availability of CO intermediate in Ni/C core and the dimerization of key∗CO intermediates,as well as the subsequent proton-electron transfer process on the Cu/C shell.

具有高效氧还原反应催化活性的共轭三嗪骨架材料负载的单原子钴催化剂

单原子钴是一种理想的代替铂催化氧还原反应(ORR)的非贵金属催化剂,然而制备低成本、高稳定性且高效的此类催化剂仍面临挑战.这需要高效的制备策略以及强健的支撑材料以稳定单原子钴.因此,我们提出了一种适于大量制备的三嗪骨架材料负载的单原子钴ORR催化剂(Co-CTF/KB).其单原子钴负载量达4 wt%,在碱性介质中ORR催化性能超过商用Pt/C和大部分已报道的非贵金属催化剂:半波电位(E_(1/2))达0.830 V,截止电流为6.14 mA cm^(-2),且具有极高的甲醇耐受性.得益于CTF对钴单原子的强稳定性,Co-CTF/KB催化循环10000圈后,电位偏移仅5 mA,展现出极好的循环稳定性.此外,Co-CTF/KB还能催化析氧反应(OER),是一种高效、高稳定的ORR/OER双功能催化剂.此工作为规模化制备高质量的单原子催化剂提供了新思路.