Phase composition,conductivity,and sensor properties of cerium-doped indium oxide

The hydrothermal synthesis of In_(2)O_(3)and CeO_(2)–In_(2)O_(3)is investigated as well as the properties of sensor layers based on these compounds.During the synthesis of In_(2)O_(3),intermediate products In(OH)_(3)and InOOH are formed,which are the precursors of stable cubic(c-In_(2)O_(3))and metastable rhombohedral(rh-In_(2)O_(3))phases,respectively.A transition from c-In_(2)O_(3)to rh-In_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-In_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-In_(2)O_(3).The data on the sensor activity of the composites correlate with XPS results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-In_(2)O_(3).The reverse situation is observed in composites based on c-In_(2)O_(3).Compared to In_(2)O_(3)and CeO_(2)–In_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between In_(2)O_(3)and CeO_(2).

Cerium-tungsten oxides supported on activated red mud for the selective catalytic reduction of NO_(x)

Activated red mud(RM)has been proved to be a promising base material for the selective catalysis reduction(SCR)of NOx.The inherent low reducibility and acidity limited its low-temperature activity.In this work,molybdenum oxide,tungsten oxide,and cerium oxide were used to reconfigure the redox sites and acid sites of red mud based catalyst.When activated red mud was reconfigured by cerium-tungsten oxide(Ce-W@RM),the NOx conversion kept above 90%at 219-480℃.The existence of Ce^(3+)/Ce^(4+) redox electron pairs provided more surface adsorbed oxygen(O_(α)) and served as a redox cycle.Positive interactions between Ce,W species and Fe oxide in red mud occurred,which led to the formation of unsaturated chemical bond and promoted the activation of adsorbed NH_(3) species.WO_(3) and Ce_(2)(WO_(4))_(3)(formed by solid-state reaction between Ce and W species)could provide more Brønsted acid sites(W-O modes of WO_(3),W=O or W-O-W modes of Ce_(2)(WO_(4))_(3)).CeO_(2) species could provide more Lewis acid sites.The Langmuir-Hinshelwood(L-H)routes and Eley-Rideal(E-R)routes occurred in the low-temperature SCR reaction on the Ce-W@RM surface.NH_(4)^(+) species on Brønsted acid sites,NH_(3) species on Lewis acid sites,bidentate nitrate and bridging nitrate species were key active intermediates species.

Cerium Methacrylate Assisted Preparation of Highly Thermally Conductive and Anticorrosive Multifunctional Coatings for Heat Conduction Metals Protection

Preparing polymeric coatings with well corrosion resistance and high thermal conductivity(TC)to prolong operational life and ensure service reliability of heat conductive metallic materials has long been a substantive and urgent need while a difficult task.Here we report a multifunctional epoxy composite coating(F-CB/CEP)by synthesizing cerium methacrylate and ingeniously using it as a novel curing agent with corrosion inhibit for epoxy resin and modifier for boron nitride through"cation-π"interaction.The prepared F-CB/CEP coating presents a high TC of 4.29 W m^(−1)K^(−1),which is much higher than other reported anti-corrosion polymer coatings and thereby endowing metal materials coated by this coating with outstanding thermal management performance compared with those coated by pure epoxy coating.Meanwhile,the low-frequency impedance remains at 5.1×10^(11)Ωcm^(2)even after 181 days of immersion in 3.5 wt%NaCl solution.Besides,the coating also exhibits well hydrophobicity,self-cleaning properties,temperature resistance and adhesion.This work provides valuable insights for the preparation of high-performance composite coatings with potential to be used as advanced multifunctional thermal management materials,especially for heat conduction metals protection.

Three-dimensional numerical simulation of heating and melting behaviors of cerium oxide powders in radio frequency thermal plasma

The present study aims at the numerical simulations of the melting process of cerium oxide particles in RF thermal plasma.The physical model and the calculating method were described firstly;the interaction between cerium oxide particles and plasma was analyzed;specific attention was given to the effects of particle initial size,injection velocity on the particle melting and trajectory in plasma.The influence of the temperature field and velocity field distribution of the plasma around the particle trajectory on the melting effect is analyzed,and the relationship between the heat absorption efficiency of the particles and the particle size reduction process is further determined.It is also found that there exists an optimal particle initial injection velocity which led to a more concentrated final particle size distribution and a more significant reduction of particle size.The results could provide effective guidance for understanding the plasma spheroidization process of uranium dioxide and cerium dioxide powder particles.

Nano transdermal system combining mitochondria-targeting cerium oxide nanoparticles with all-trans retinoic acid for psoriasis

Psoriasis is an inflammatory skin disease that is intricately linked to oxidative stress.Antioxidation and inhibition of abnormal proliferation of keratinocytes are pivotal strategies for psoriasis.Delivering drugs with these effects to the site of skin lesions is a challenge that needs to be solved.Herein,we reported a nanotransdermal delivery system composed of all-trans retinoic acid(TRA),triphenylphosphine(TPP)-modified cerium oxide(CeO2)nanoparticles,flexible nanoliposomes and gels(TCeO_(2)-TRA-FNL-Gel).The results revealed that TCeO_(2)synthesized by the anti-micelle method,with a size of approximately 5 nm,possessed excellent mitochondrial targeting ability and valence conversion capability related to scavenging reactive oxygen species(ROS).TCeO_(2)-TRA-FNL prepared by the film dispersion method,with a size of approximately 70 nm,showed high drug encapsulation efficiency(>96%).TCeO_(2)-TRA-FNL-Gel further showed sustained drug release behaviors,great transdermal permeation ability,and greater skin retention than the free TRA.The results of in vitro EGF-induced and H2O2-induced models suggested that TCeO_(2)-TRA-FNL effectively reduced the level of inflammation and alleviated oxidative stress in HaCat cells.The results of in vivo imiquimod(IMQ)-induced model indicated that TCeO_(2)-TRA-FNL-Gel could greatly alleviate the psoriasis symptoms.In summary,the transdermal drug delivery system designed in this study has shown excellent therapeutic effects on psoriasis and is prospective for the safe and accurate therapy of psoriasis.

Cerium-promoted conversion of dinitrogen into high-energy-density material CeN_(6) under moderate pressure

Synthesis pressure and structural stability are two crucial factors for highly energetic materials,and recent investigations have indicated that cerium is an efficient catalyst for N2 reduction reactions.Here,we systematically explore Ce–N compounds through first-principles calculations,demonstrating that the cerium atom can weaken the strength of the N≡N bond and that a rich variety of cerium polynitrides can be formed under moderate pressure.Significantly,P1-CeN_(6) possesses the lowest synthesis pressure of 32 GPa among layered metal polynitrides owing to the strong ligand effect of cerium.The layered structure of P1-CeN_(6) proposed here consists of novel N_(14) ring.To clarify the formation mechanism of P1-CeN_(6),the reaction path Ce+3N2→trans-CeN_(6)→P1-CeN_(6) is proposed.In addition,P1-CeN_(6) possesses high hardness(20.73 GPa)and can be quenched to ambient conditions.Charge transfer between cerium atoms and N_(14) rings plays a crucial role in structural stability.Furthermore,the volumetric energy density(11.20 kJ/cm^(3))of P1-CeN_(6) is much larger than that of TNT(7.05 kJ/cm^(3)),and its detonation pressure(128.95 GPa)and detonation velocity(13.60 km/s)are respectively about seven times and twice those of TNT,and it is therefore a promising high-energy-density material.

Cerium Oxide Nanoparticles Protect against Oxaliplatin Induced Testicular Damage: Biochemical, Histological, Immunohistochemical, and Genotoxic Study

Oxaliplatin is a chemotherapeutic drug used for colorectal cancer treatment. The testicular toxic effect is one of its recorded toxicities which resulted in a few studies. Oxidative stress could be a direct cause of this testicular toxicity. Cerium oxide nanoparticles (CONPs) are optimistic antioxidants for applications in medicine. The aim of the work is to study the protective effect of CONPs on testicular toxicity induced by oxaliplatin in rats. Forty adult male albino rats were divided into 4 groups: Control group, CONPs group (60 mg/kg, 5 times/week), Oxaliplatin group (4 mg/kg, twice/week), and Oxaliplatin & CONPs group, for 4 weeks. Seventy-two hours after the last administration, blood samples were taken for hormonal levels and testes were used for both histopathology and immunohistochemical microscopic examination. Sperm smears were also performed and their results were statistically analyzed to detect any sperm abnormalities. Oxaliplatin increased MDA levels. SOD and GPx activity was decreased. GSH levels were decreased. Also, it decreased the sperm cell count and serum testosterone, and anti-Müllerian hormon. In the testicular sections, significant histopathology changes were seen and immunohistochemical examination confirmed these results. Upon supplementation of CONPs with oxaliplatin decreased MDA levels. SOD and GPx activity was increased, and GSH did not change. In testicular sections, normal morphology was seen. Also, there was an increase in the sperm cell count and serum testosterone anti-Müllerian with significant improvement of testicular architecture, and immunohistochemical examination confirmed these results. The utilization of CONPs produced significant protection against all of the above-mentioned changes.

石墨烯基介孔锰铈氧化物催化剂:制备和低温催化还原NO

锰铈氧化物由于较强的氧化还原活性、优良的低温脱硝性能,已被广泛用于选择性催化还原(SCR)脱硝反应,但是锰铈氧化物存在活性组分易团聚、比表面积较低等问题,限制其催化剂活性的提高。本研究以介孔结构的石墨烯基SiO_(2)(G@SiO_(2))纳米材料为模板,采用水热法制备了系列石墨烯基介孔锰铈氧化物(G@MnO_(x)-CeO_(2))催化剂,并考察了该催化剂在低温下(100~300℃)的SCR脱硝性能。结果表明,与石墨烯基铈氧化物(G@CeO_(2))相比,G@MnO_(x)-CeO_(2)催化剂具有较高脱硝活性。当Mn、Ce与模板G@SiO_(2)质量比分别为0.35、0.90时,G@Mn(0.35)Ce(0.9)催化剂的脱硝活性最佳,220℃下NO转化率达到最高(80%)。添加适量MnO_(x),提高了G@MnO_(x)-CeO_(2)催化剂的比表面积、孔容,降低了催化剂的结晶度;并且MnO_(x)-CeO_(2)以纳米尺度(2~3 nm)较为均匀地分散于石墨烯片层表面。此外,由于MnO_(x)与CeO_(2)之间存在协同作用,Mn原子可以部分替代Ce原子掺杂于CeO_(2)的晶体结构中形成MnO_(x)-CeO_(2)固溶体,使G@Mn(0.35)Ce(0.9)催化剂表面存在较高含量的高价态Mn^(3+)和Mn^(4+)、Ce^(4+)以及较高的化学吸附氧浓度,从而展现出较高的脱硝性能。该工作为MnO_(x)-CeO_(2)基催化剂在低温NH3-SCR中的实际应用提供了基础数据。

CuCe-SAPO-34选择性催化丙烯还原柴油车尾气氮氧化物

采用等体积浸渍法制备Cu Ce-SAPO-44分子筛催化剂,用于选择性催化丙烯还原柴油车尾气氮氧化物(C3H_(6)-SCR)。采用X射线衍射(XRD)、N_(2)吸附-脱附、紫外可见光谱(UV-Vis)、H_(2)程序升温还原(H_(2)-TPR)和NH3程序升温脱附(NH3-TPD)等方法对催化剂的物理化学性质进行表征。研究表明,引入的铈与铜物种之间存在相互作用,有利于生成更多的孤立Cu^(2+)物种,提高了分子筛催化剂的低温氧化还原性能,从而提高了Cu CeSAPO-34的低温脱硝活性。同时,双金属分子筛骨架上具有丰富的Lewis酸性位,有助于C3H_(6)和NO_(x)的吸附和活化。当Cu∶Ce=4∶2时,Cu Ce-SAPO-34催化剂具有最佳的脱硝性能,在含有10%O_(2)和5%H_(2)O的柴油车尾气氛围中,在250℃最高能实现90%以上的脱硝效率。

加热温度对工业规模CeCl_(3)喷雾焙烧反应器影响的数值模拟

CeO_(2)颗粒由于具有优异的性能,市场对CeO_(2)颗粒的需求逐年增加。为探究使用在氧化铁颗粒工业化生产的Ruthner型喷淋焙烧反应器生产CeO_(2)颗粒的可能性,结合单液滴失重试验,使用ANSYS Fluent软件,分别探究550、650、750和850℃四种不同加热温度对反应器的影响。单液滴失重试验表明,氯化铈和氯化铁、氯化亚铁的热解过程基本一致,使用该型反应器制备CeO_(2)颗粒理论上可行。对小型工业反应器进行等比例建模,研究反应器内部化学反应的具体过程。结果表明,550℃是最合适的温度,对工业生产具有一定指导意义。

喷雾热解法加热壁温对铈锆固溶体生产过程的影响

【目的】为了探究喷雾热解过程中加热壁温对铈锆固溶体生产过程的影响,分析热解炉内的流量场和浓度场的变化情况,实现对热解炉的设计优化。【方法】采用数值模拟的方法,建立喷雾热解炉的物理模型,分别探讨加热壁温对铈锆固溶体在热解炉的不同阶段及热解炉中水蒸气分布和HCl分布的影响。【结果】当热解温度为850℃时,液滴的反应主要分2个阶段,在炉膛高度为0~0.05 m处,为加热蒸发阶段,在炉膛高度为0.05~0.6 m处,为稳态热解阶段。当炉壁温度为550~650℃时,在炉膛高度为0.9 m处温度变化放缓,喷雾处于稳定热解阶段;而壁温在750~850℃时,在炉膛高度为0.6 m处温度变化放缓;当壁温为850℃时,在炉膛高度为0.1~0.6 m处的温度曲线斜率最大,液滴达到稳定蒸发阶段的时间缩短,水分蒸发变快,热解时间变短。【结论】炉壁加热区的温度越高,HCl生成的速度越快,速度的最大值越小,在炉膛高度为0.4 m处速度变化最大,达到1.6 m/s左右;并且整体HCl生成的量随温度的升高而增大,平均速度变化随着热空气温度的升高而减小。

氯化铈液滴在喷雾焙烧反应器热解过程的数值模拟研究

Ruthner型喷雾焙烧反应器具有节能、环保和副产物可回收利用等诸多优点,其已被广泛应用于回收钢铁工业酸洗液,但在CeO_(2)颗粒制备领域还没有应用。当前对实心球形CeO_(2)颗粒的需求不断扩大,使得应用Ruthner型喷雾焙烧反应器规模化生产CeO_(2)颗粒具有诱人的前景。由于焙烧反应过程难以通过试验表征,使用ANSYS Fluent仿真软件对焙烧反应过程进行仿真模拟,可直观表现出CeCl_(3)热解生成CeO_(2)颗粒的过程。本研究首先通过热重试验,验证了铁元素的氯化物和铈元素的氯化物的热解过程完全一致,只是温度不同:CeCl_(3)液滴在200℃时完全失去自由水,在500℃时完全反应;FeCl_(2)液滴在180℃完全失去自由水,在420℃时完全反应;FeCl_(3)液滴在160℃完全失去自由水,在410℃时完全反应,因此使用处理酸洗液的反应器生产CeO_(2)颗粒理论上可行。进一步,通过使用仿真软件包中的两相流、组分输运等模型,探究反应器内温度场、速度场和浓度场等分布,结果表明在反应器内部,某区域内温度越高,对应的气流、颗粒运动速度就越快。

铈改性磁性核壳HZSM-5催化富油煤热解研究

【目的】富油煤是集煤、油气属性为一体的宝贵煤炭资源,催化热解是实现其绿色低碳开发的重要途径。然而,高效可回收催化剂的研发仍面临着极大的挑战。【方法】以HZSM-5@SiO_(2)@MgFe_(2)O_(4)(HSMF)为原料,采用水热法与碱改性制备具有多级孔结构的HZSM-5@SiO_(2)@MgFe_(2)O_(4)(mHSMF),再通过沉淀法制备铈改性mHSMF(5-CeO_(2)/mHSMF);并利用固定床反应器考察了5-CeO_(2)/mHSMF对神府富油煤热解产物的调控作用及其抗积炭性能。【结果和结论】结果表明,CeO_(2)改性有助于在HSMF表面形成微−介孔多级孔道结构;在5-CeO_(2)/mHSMF催化剂上,650℃、N_(2)气氛、反应1 h的条件下,神府富油煤焦油产率达到13.38%,是格金试验焦油产率的176%;相较于原煤热解,催化热解得到的焦油中脂肪烃类及苯类化合物含量分别增加了3.04%和3.07%,煤气中H_(2)和CH_(4)含量提高了10.49%;经CeO_(2)改性后,催化剂的抗积炭性能增幅达86.1%,积炭量仅为11.60 mg/g,且积炭趋于稳定的石墨化结构。5-CeO_(2)/mHSMF对神府富油煤催化热解产物的分布及组成具有明显调控作用,并表现出良好的抗积炭效果和磁性可回收性能。

二氧化铅电极改性及电催化降解焦化废水中蒽

为了研究电催化对焦化废水中污染物的降解效果,采用电沉积法制备了Ti/PbO_(2)、Ti/PANI/PbO_(2)和Ti/PANI/PbO_(2)-Ce三种电极,对电极进行扫描电镜和X射线衍射表征、电化学性能测试、产羟基自由基(·OH)能力测试和加速寿命测试。结果表明,经聚苯胺(PANI)和铈(Ce)改性的Ti/PANI/PbO_(2)-Ce电极具有更好的表面形貌和更高的催化活性,能产生更多的·OH,析氧电位为1.83 V,加速寿命时间为720 min。采用Ti/PANI/PbO_(2)-Ce电极降解焦化废水中的蒽,考察了主要因素对降解效果的影响,得到蒽的最佳降解条件为电压14 V,板间距1.0 cm,电解质浓度0.35 mol/L,反应时间120 min,pH值10。Ti/PANI/PbO_(2)-Ce电极显示了良好的电催化性能。

氧化铈负载聚己内酯创面敷料在神经外科术后护理中的应用效果研究

目的:探讨氧化铈负载聚己内酯创面敷料在神经外科开颅患者术后伤口护理中的应用效果,为临床术后护理及降低并发症发生率提供依据。方法:选取2021年2月—2022年12月哈尔滨医科大学附属第四医院收治的124例接受神经外科开颅手术的患者作为研究对象,根据住院号的奇偶数将其分为对照组和实验组,每组各62例。对照组患者的手术伤口采用传统外科敷料进行覆盖,实验组患者使用氧化铈负载聚己内酯敷料进行覆盖,比较两组患者伤口无菌拭子培养阳性率、伤口愈合比值、伤口换药平均出血量和不良反应发生情况。结果:实验组患者术后第2天、第4天、第6天的伤口无菌拭子培养阳性率明显低于对照组,差异有统计学意义(χ^(2)=4.888、4.593、5.962,P<0.05)。术后当天、第2天、第4天、第6天,实验组患者的伤口愈合比值明显低于对照组,差异有统计学意义(χ^(2)=-2.813、2.552、2.544、5.555,P<0.05)。实验组患者伤口换药平均出血量明显低于对照组,差异有统计学意义(t=2.555,P<0.05)。实验组患者不良反应发生率明显低于对照组,差异有统计学意义(χ^(2)=8.798,P<0.05)。结论:在神经外科开颅患者术后的伤口护理中应用氧化铈负载聚己内酯创面敷料,能够降低患者伤口无菌拭子培养阳性率、伤口愈合比值、伤口换药平均出血量及不良反应发生率。

CO优先氧化反应MnCu/Ce催化剂的制备及性能

采用共浸渍法制备较低Cu含量的MnCu/Ce催化剂,通过XRD、BET、H_(2)-TPR、XPS和CO_(2)-TPD等表征手段对催化剂进行表征,考察催化剂焙烧温度对催化剂结构、性质及其在含有CO_(2)的富氢气氛下对CO优先氧化性能的影响。结果表明,MnCu/Ce催化剂均有Cu/Mn-O-Ce固溶体形成,其中,在焙烧温度600℃制备的催化剂中,Mn与Cu、Ce之间相互作用较强,形成较多三元氧化物固溶体,氧空位/Ce^(3+)含量高,具备良好的CO-Prox活性。此外,对反应条件的考察发现,添加不同分压Ar对催化剂的CO-Prox活性影响较小,气体空速和氧过量系数对催化剂活性影响较大,且反应原料气中CO_(2)的存在对CO-Prox反应有负面影响。氧过量系数为1.2、空速范围为20266-30400 mL/(g·h)时,CO转化率最高,达到94.7%。

纳米氧化铈对无脊椎动物的毒性效应

近年来,纳米氧化铈(CeO_(2)NPs)独特的理化性质使其生产规模和应用范围逐渐扩大,但CeO_(2)NPs在生产、运输和商品化过程中不可避免地被释放到环境中,具有环境污染的潜在风险,其生物安全性受到越来越多的关注.无脊椎动物是生物类群的重要组成,本文研究了国内外近十年的科学文献,综述了CeO_(2)NPs在生物累积、行为反应、组织损伤、生长发育毒性、免疫毒性、生殖毒性、遗传毒性等方面对无脊椎动物的影响以及CeO_(2)NPs毒性效应影响因素,总结了CeO_(2)NPs对无脊椎动物的毒性机制,最后对未来研究方向进行了展望,以期为CeO_(2)NPs的毒性评价、安全生产与应用提供参考.

钙铈基催化剂上碳酸丙烯酯和甲醇制备碳酸二甲酯的研究

采用溶胶凝胶法制备了不同比例的钙铈基催化剂,并研究了其对于碳酸丙烯酯和甲醇制备碳酸二甲酯的酯交换反应性能。结果表明,Ca∶Ce=9的催化剂在反应时间2 h,温度40℃,甲醇与碳酸丙烯酯物质的量比为15∶1,催化剂用量为碳酸丙烯酯用量4%的条件下,碳酸丙烯酯转化率达到91.1%,碳酸二甲酯选择性达到91.7%。采用XRD、N2吸附-脱附、FT-IR、XPS和CO_(2)-TPD对催化剂进行了表征。结果表明,催化剂表面的氧空穴越多,中等碱性位数量越多,越有利于甲醇的活化,催化剂的活性越好。

低硫柴油用纳米氧化铈抗磨助燃添加剂的性能研究

为了解决深度脱硫工艺导致的柴油摩擦学性能差引起的喷油器磨损失效问题及纳米添加剂粒径大分散性差等问题,制备了超小粒径(1~2 nm)CeO_(2)纳米微粒,其拥有优异的分散性。将其作为0号柴油添加剂,采用四球摩擦磨损试验机和自动量热仪测试了其摩擦学性能和助燃性能,采用热重分析仪在氧气气氛下分析柴油的氧化燃烧过程。结果表明,向柴油中添加CeO_(2)纳米微粒能够增强其减摩抗磨性能,与柴油相比磨斑直径减小约13%,摩擦系数降低约27%,燃烧热值提高约16%。

基于金纳米粒子-纳米氧化铈-石墨烯复合物修饰电极对环境水体中As(Ⅲ)的检测

先通过滴涂法制备纳米氧化铈-石墨烯(CeO_(2)-Gr)复合物修饰玻碳电极(GCE),再在含氯金酸(HAuCl_(4))的缓冲溶液中,采用循环伏安法将Au(Ⅲ)还原到CeO_(2)-Gr表面,从而制得AuNPs/CeO_(2)/Gr/GCE。采用电化学阻抗谱法(EIS)对修饰电极进行电化学特性表征。研究了AuNPs/CeO_(2)/Gr/GCE快速、准确测定水环境中As(Ⅲ),采用差分脉冲溶出伏安法,探讨了氧化铈与石墨烯质量比、金纳米粒子沉积圈数、沉积时间和沉积电位及干扰离子等对测定结果的影响,并确定检测As(Ⅲ)的优化实验条件。在最优条件下,该电化学传感器对As(Ⅲ)具有良好的电流响应,其溶出伏安峰电流与As(Ⅲ)浓度的线性范围为13.35~387.15μmol/L,检出限为4.74μmol/L。在不同干扰离子存在的情况下,传感器对As(Ⅲ)的选择性较好。为了评估传感器的实际应用能力,以实验室自来水为样本进行As(Ⅲ)加标检测,加标回收率为90.5%~99.2%,表明该电化学传感器具有监测As(Ⅲ)的应用潜力。