Acidity Modification of ZSM-5 for Methane Conversion in Co-feeding Method with MTA Reaction

Acidity plays a vital role in methane conversion by co-feeding method, which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane. In this work, Zn, Ni, Mo, La, Ga, Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane. It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction. Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%, whose aromatic selectivity increases from 27.2% to 52.2% compared with that of HZSM-5. Besides, the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics (MTA) reaction.     

In vivo Toxicity Evaluation of a Nano-drug Delivery System Using a Caenorhabditis elegansModel System

Drug carrier materials need to possess good biological safety. Presently, most biosafety evaluation studies use rodent animal models, including rats and rabbits. However, the cost of raising these animals is relatively high and the experimental period is long. Caenorhabditis elegans(C. elegans) presents an ideal toxicological evaluation model due to its simple structure, easy cultivation, short life cycle, and evolutionary conservation. In this paper, we used C. elegans to test the biological safety of our pH-responsive carrier system(FFPFF self-assembling into a nanosphere structure, FFPFF Nps), which was designed for anti-tumor drug delivery. Our results showed that exposure to high doses of FFPFF Nps did not have a significant impact on the survival rate, growth, development, movement, and reproduction of C. elegans. The preliminary evaluation of the overall biological model of C. elegans shows that FFPFF Nps has good biological safety and warrants further study.     

A Nitrogen,Sulfur co-Doped Porphyrin-based Covalent Organic Framework as an Efficient Catalyst for Oxygen Reduction

Oxygen reduction reaction(ORR) is a significant reaction for energy conversion systems(such as fuel cells, metal-air batteries, etc.). It is an urgent need to develop cheap, durable and highly-active catalysts for efficient ORR. Hence, we report a metal-free nitrogen and sulfur co-doped porphyrin-based covalent organic framework(COF) as a high-efficiency ORR catalyst[the onset potential(E_o) is 0.79 V and the half-wave potential(E_1/2) is 0.70 V]. The double doping of N and S atoms causes uneven charge distribution around carbon atoms, which can act as catalytic active centers, improving ORR activity. Compared with single-atom doping, double atoms doping exhibits a higher activity due to the synergistic effect between different elements. These results demonstrate that reasonable design of stable metal-free COFs with a high electrochemical activity can promote their wide applications.     

Removal of Anionic Dyes from Aqueous Solution with Layered Cationic Aluminum Oxyhydroxide

It is highly desired yet challenged to find an adsorbent with low cost and excellent performance in the removal of organic dyes from aqueous solution. Here we reported that a layered cationic aluminum oxyhydroxide material hydrothermally synthesized from the low-cost source materials of AlCl₃∙6H₂O, CaO and H₂O, known as JU-111, can meet such criterion in removing methyl orange(MO) and Congo red(CR). JU-111 shows fast adsorption kinetics[especially for CR(15 s)] and high adsorption capacity(MO:>1000 mg/g; CR:>2900 mg/g), surpassing most of the reported adsorbents. Comprehensive characterizations of the adsorption process of MO and CR revealed that both adsorptions were achieved via the anion exchange process. The characteristics of extremely low cost and excellent performance render JU-111 great potential in the practical applications in the removal of anionic dyes.     

Single-atom Fe Embedded Co3S4 for Efficient Electrocatalytic Oxygen Evolution Reaction

Constructing atomically dispersed active sites with densely exposed and dispersed double metal-S_x catalytic sites for favorable OER catalytic activity remains rare and challenging. Herein, we design and construct a Fe₁S_x@Co₃S₄ electrocatalyst with Fe single atoms epitaxially confined in Co₃S₄ nanosheets for catalyzing the sluggish alkaline oxygen evolution reaction(OER). Consequently, in ultralow concentration alkaline solutions(0.1 mol/L KOH), such a catalyst is highly active and robust for OER with low overpotentials of 300 and 333 mV at current densities of 10 and 30 mA/cm², respectively, accompanying long-term stability without significant degradation even for 350 h. In addition, Fe₁S_x@Co₃S₄ shows a turnover frequency(TOF) value of 0.18 s⁻¹, nearly three times that of Co₃S₄(0.07 s⁻¹), suggesting the higher atomic utilization of Fe single atoms. Mössbauer and in-situ Raman spectra confirm that the OER activity of Fe₁S_x@Co₃S₄ origins from a thin catalytic layer of Co(Fe)OOH that interacts with trace-level Fe species in the electrolyte, creating dynamically stable active sites. Combined with experimental characterizations, it suggests that the most active S-coordinated dual-metal site configurations are 2S-bridged (Fe-Co)S₄, in which Co-S and Fe-S moieties are shared with two S atoms, which can strongly regulate the adsorption energy of reaction intermediates, accelerating the OER reaction kinetics.     

卟啉-硫醚基共价有机框架材料用于氧还原反应电催化剂

氧还原反应（ORR）是能进行能量存储的核心电化学过程。由于它的动力学速率缓慢,因此亟需制备出高活性的电催化剂来促进这一反应的速率。二维共价有机框架材料（2D COFs）的π-π堆积结构可赋予骨架高导电率,并且一维有序的孔道有利于促进中间反应体传输。因此,其在可再生能源领域中具有良好的应用前景,并有望作为能量存储与转化的强大催化平台。本文通过向2D COFs中引入金属卟啉单元及硫醚单元成功制备了两个2D COFs （JUC-600和JUC-601）。通过多种表征手段证明,这两个2D COFs均具有AA堆积的sql拓扑结构。通过电化学测试表明,Co²⁺配位的JUC-601具有更正的ORR起始电势（0.825 V）和半波电势（0.7 V）、更高的活性表面积（7.8 mF/cm²）,更低的Tafel斜率（58 mV/dec）。这主要是由于JUC-601的高比表面积和高孔隙率使得中间产物能更易在COFs的表面和孔道中接触和传输。此外,Co²⁺-卟啉单元以及硫醚单元的存在使其骨架整体的电子结构发生了变化,更有利于电子转移。这一工作不仅开发了新的二维卟啉-硫醚基COFs材料,同时也拓展了2D COFs材料在电催化领域的应用。     

电化学还原二氧化碳合成碳材料电催化还原氧气合成过氧化氢北大核心CSCD

研究了3种不同阳极(铜丝,镀锌铁丝和镍丝)材料对在熔盐中电化学还原CO_(2)制备的碳材料结构和形貌的影响,并探究了制备的3种碳材料,中空四面体碳(HQC,Cu作为阳极时的还原产物)、碳纳米片(CNS,Fe作为阳极时的还原产物)和海绵状多孔碳(SPC,Ni作为阳极时的还原产物),对2电子氧还原反应(2e;ORR)的电催化性能。研究表明,使用镀锌铁丝作为阳极材料制备的CNS由大量的碳纳米片构成,且该纳米片上具有丰富的孔洞结构以及较大的I_(D)/I_(C)(Raman光谱中D峰与G峰的强度之比,其比值反映材料的缺陷程度)值(0.996)。与HQC和SPC相比,CNS表现出最高的2e;ORR电催化活性和H_(2)O_(2)选择性(接近90%)。CNS的高活性和高选择性归因于其高的I_(D)/I_(C)值和高C—O/C=O比值,说明结构缺陷和C—O/C=O官能团对CNS催化性能至关重要。此外,CNS还具有非常优异的电催化稳定性,在长达14 h的恒电压电化学催化测试后,环电流几乎无衰减。这种以CO_(2)为碳源合成可用于电催化合成过氧化氢(H_(2)O_(2))的碳材料的方法,不仅可以作为缓解温室效应的潜在选项,也为CO_(2)衍生碳的实际应用提供了新的思路。     

黏惰化及酸敏感修饰对纳米粒子黏膜穿透的影响

使用纳米粒子进行疾病的诊断和治疗是当前研究的一个热点. 由于受到黏液层的阻碍, 纳米粒子对于黏膜上皮细胞的进入效果不佳, 从而限制了其对黏膜相关疾病的诊断和治疗. 本文设计合成了一种具有黏惰性的酸敏感纳米粒子(MSNs-pCBMA-DMMA), 可有效穿透黏液层进入黏膜上皮细胞. 首先采用溶胶-凝胶法合成了表面氨基化的介孔二氧化硅纳米粒子(MSNs-NH₂), 然后通过原子转移自由基聚合法(ATRP)使两性离子羧基甜菜碱甲基丙烯酸酯(CBMA)在MSNs-NH₂表面上聚合形成聚羧基甜菜碱甲基丙烯酸酯(pCBMA), 获得惰性化的粒子(MSNs-pCBMA), 最后将酸响应性分子2,3-二甲基马来酸酐(DMMA)修饰于MSNs-pCBMA表面, 制备了MSNs-pCBMA-DMMA. 场发射透射电子显微镜(TEM)、 傅里叶变换红外光谱(FTIR)、 氢核磁共振波谱(¹H NMR)和纳米粒度Zeta电位测定仪等分析结果表明, 本文合成了MSNs-pCBMA-DMMA, 且粒子表面电位随pH值降低显著增加, 在pH=7.4~5.7范围内具有酸敏感能力. Transwell^?小室实验表明, pCBMA的接枝提高了粒子在模拟黏液中的渗透速率, 而DMMA的修饰则进一步增强了粒子的扩散能力, 4 h内MSNs-pCBMA-DMMA的模拟黏液渗透率达到16.3%, 为MSNs-pCBMA的1.9倍, MSNs-NH₂的3倍, 而以MSNs-NH₂的表观渗透系数（P_app）为标准计算得到的MSNs-pCBMA-DMMA的相对表观渗透系数达到了2.96. 细胞毒性试验验证MSNs-pCBMA-DMMA粒子的生物安全性良好. 细胞摄取试验表明, 相比于其它粒子MSNs-pCBMA-DMMA能够更快的被黏膜上皮细胞摄取. 本文所构建的纳米粒子能够快速渗透黏液且易于被黏膜上皮细胞摄取, 为其应用于黏膜相关疾病的活体诊断和治疗提供了基础.     

等级孔微孔-介孔Fe2O3/ZSM-5中空分子筛催化材料的制备及催化苄基化性能

ZSM-5分子筛具有极其均匀的孔道结构、 良好的形状选择性和催化活性及耐水热稳定性, 是一种高效、 绿色的固体催化剂, 被广泛应用于石油催化裂化、 精细化工和环境保护等领域. 但其单一的微孔结构大大降低了客体分子的流通扩散性, 导致由大分子参与的芳烃烷基化反应受到极大限制. 本文采用NaOH/四丙基氢氧化铵(TPAOH)混合碱处理微孔ZSM-5, 制备了具备高结晶度、 高比表面积的等级孔微孔-介孔ZSM-5中空分子筛材料, 该材料在保持微孔孔道良好水热稳定性和大量活性中心的同时, 还通过介孔的引入进一步促进反应物及产物的扩散, 使间三甲苯苄基化反应的转化率提高了3.8倍. 通过在等级孔微孔-介孔ZSM-5中空材料上负载Fe, 开发出了具有双功能的等级孔微孔-介孔Fe₂O₃/ZSM-5中空催化剂, 该催化剂在苯的苄基化反应中表现出优异的催化性能, 当Fe负载量(质量分数)为6.67%, 反应温度为75 ℃, 反应时间为15 min时, 转化率高达98.3%, 选择性为81.6%, 最终收率达到80.2%.     

CO2在非质子溶剂与铁基离子液体复合体系中的吸收

选用非质子型有机溶剂聚乙二醇二甲醚(NHD)与N, N-二甲基乙酰胺(DMAC), 分别与BmimFeCl₄复配, 构建了BmimFeCl₄/NHD和BmimFeCl₄/DMAC复合铁基离子液体体系. 考察了温度、 BmimFeCl₄/溶剂的质量 比以及压力对CO₂在复合铁基离子液体体系中溶解行为的影响. 结果表明, 高压低温的吸收条件更利于CO₂ 的溶解, 当BmimFeCl₄/DMAC质量比为7∶3时, CO₂在BmimFeCl₄/DMAC复合体系中的亨利系数为0.9181 MPa·L·mol^-1, 低于同等条件下BmimFeCl₄/NHD体系的亨利系数. 在常压、 363.2 K条件下进行再生, 经5次循环后, CO₂在BmimFeCl₄/NHD和BmimFeCl₄/DMAC中的溶解度分别为初次吸收量的92.53%和99.04%. 傅里叶变换红外光谱(FTIR)结果表明, 铁基离子液体复配体系吸收CO₂为物理吸收过程. 密度泛函理论(DFT)计算与IRI分析的结果表明, 在复配DMAC的体系中, CO₂更倾向与阳离子和溶剂分子作用, 而在复配NHD的体系中, CO₂则更容易与阴离子和溶剂分子作用.