H2C2O4稳定剂对SOl-Gel法制备LiNbO3薄膜的影响

研究了分别以H2C2O，HNO3，HCOOH和CH3COOH作稳定剂的LiNbO3薄膜先驱液的稳定性，发现H2C2O4作稳定剂的先驱液的稳定性最好，用sol-gel法在Si(110)基板上制备了以H2C2O4作稳定剂的LiNbO3薄膜，并对LiNbO3薄膜进行了IR，XRD和SEM表征，结果表明，生成的LiNbO3为多晶，与HNO3相比，以H2C2O4作稳定剂制备的LiNbO3薄膜形貌较差。     

“珠串”堆叠超结构的介孔铁酸锌的制备与表征

以硫酸亚铁和硝酸锌为铁源和锌源,十二烷基硫酸钠为颗粒尺寸控制剂,草酸钠为沉淀剂,通过草酸盐的热分解制备了介孔铁酸锌.利用X射线粉末衍射、热分析、红外光谱、场发射扫描电镜和氮气吸附脱附等手段对不同表面活性剂加入量制备的样品的晶相组成和表面结构进行了表征,结果显示,Fe2+和十二烷基硫酸钠的摩尔比为10∶1,煅烧温度为500℃时制备的铁酸锌有较大的表面积(82.0m2·g-1),BJH平均孔径为12.5nm,孔体积为0.257cm3·g-1,得到的介孔铁酸锌具有由尺寸均一的纳米粒子规则排列而形成的“珠串”堆叠超结构.     

Conductivity of (NH4)3[CrMo6O24H6]•7H2O Treated by Nd Chemistry-Heated Diffused Permeation

Rare earth co-permeation of (NH4)3[CrMo6O24H6]•7H2O was reported and the conductivity of (NH4)3[CrMo6O24H6] was improved by 6.734×109 times. X-ray fluorescence spectrometry (XRF), thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) have been used to character (NH4)3[CrMo6 O24H6] •7H2O and permeated sample. Experimental results showed that Nd could be permeated into the body of this sample and the XRD patterns showed great difference between (NH4)3[CrMo6O24H6] •7H2O and permeated sample. The structure of (NH4)3[CrMo6O24H6] •7H2O was destroyed and new compound MoN perhaps formed.     

Na_2SO_4·10H_2O/EG复合相变材料的制备与性能分析

以十水硫酸钠为相变材料,采用真空吸附法制备十水合硫酸钠/膨胀石墨复合相变储能材料(Na_2SO_4·10H_2O/EG),对其融化-凝固、相分离、过冷、潜热等热物性进行测试分析。结果表明:在Na_2SO_4·10H_2O中添加2%(质量分数,下同)硼砂和8%EG后,可得到理想的Na_2SO_4·10H_2O/EG固-固复合相变材料。此时,Na_2SO_4·10H_2O相分离得到消除,过冷度由13.6℃降低到0.6℃以下,相变潜热和体储能密度分别为225.77kJ·kg~(-1)和218.09MJ·m~(-3)。此外,导热率也得到提高,相比于只添加成核剂硼砂的Na_2SO_4·10H_2O PCM,储热时间缩短52.6%,放热时间缩短55.1%,经过500次急剧升温-降温循环后也未出现性能衰减,储/放热性能较好。     

MgFe2O4/Fe2O3纳米粉的溶胶-凝胶法合成及电磁波吸收特性

用热分解柠檬酸盐凝胶的方法制备了MgFe2O4／Fe2O3复合纳米粉体,用综合热分析仪、X射线衍射仪、透射电镜、纳米粒度测量仪、电磁测量仪对所制备样品的结构、粒径分布、电磁波吸收特性等进行表征。结果表明,产物为平均粒径44nm的MgFe2O4和Fe2O3的混合物,在0．1、1．0和1．8GHz处tgδ（ε″＋μ″/μ′）分别为0．206、0．265及0．614。     

Template-free preparation of non-metal (B,P,S) doped g-C3N4 tubes with enhanced photocatalytic H2O2 generation

Developing environmentally friendly methods to produce hydrogen peroxide (H2O2) has received increas-ing attention.Photocatalysis has been proved to be a sustainable technology for H2O2 production.Herein,the novel non-metal elements (B,P,and S) doped g-C3N4 tubes (B-CNT,P-CNT,and S-CNT) photocata-lysts were obtained via a hydrothermal synthesis followed by thermal polymerization.By adjusting the precursor,the yield of g-C3N4 tubes (CNT) materials has been greatly improved.The as-prepared B-CNT,P-CNT,and S-CNT photocatalysts show an enhanced photocatalytic H2O2 production with the formation rate constants values of 42.31 μM min-1,24.95μM min-1,and 24.22μM min-1,respectively,which is higher than that of bulk CN (16.40 μM min-1).The doped B,P,S elements significantly enhanced the photocatalytic activity by adjusting their electronic structures and promoting the separation of electron-hole carriers.The results have shown great potential for the practical application of CNT photocatalysts.     

NiCo2O4/C复合电极材料的制备以及超级电容性能

采用化学共沉淀法合成了纳米级NiCo2O4/C复合材料,并以X射线衍射(XRD)、扫描电镜(SEM)对样品进行了结构和形貌的表征,结果表明,合成的复合材料为立方尖晶石结构,其粒径大小为30～40nm,颗粒呈球形且分布均匀。循环伏安(CV)、恒电流充放电测试表明,NiCo2O4/C复合材料在6mol/LKOH水系电解液中表现出优异的超级电容特征,在0～0.9V的电位范围内,NiCo2O4/C电极材料比电容量可高达290.49F/g,并具有良好的可逆性和优异的循环性能。     

钯钌原子比对碳载Pd-Ru催化剂催化H2O2电还原性能影响

利用化学还原法制备了不同原子比的碳载Pd-Ru催化剂,考察了钯钌原子比对碳载Pd-Ru催化剂催化H2O2电还原反应性能的影响。研究结果表明,随着Ru元素的增加,碳载Pd-Ru催化剂的粒径逐渐减小,各催化剂上H2O2电还原反应的起始还原电势稳定在0.82V,电流密度先增大后减小。当Pd∶Ru=1∶1时,PdRu/C催化剂表现了最好的催化性能。     

新型超级电容器电极材料NaxCo2O4的制备及电性能研究

采用溶胶-凝胶法制备得到Na x Co2O4(x=1.0、1.2、1.4、1.6、1.8和2.0)样品,并首次将其应用于超级电容器电极材料;经XRD、SEM和电性能研究得出,制备出的Na x Co2O4晶体均为层状结构,x=1.6时样品电容性能最好,在6mol/L NaOH电解液中,0.25~0.7V电压范围内,以50mA/g的电流密度进行恒流充放电,比电容高达413F/g。     

尖晶石型Li1-xMgxMn2O4正极材料的制备和性质

采用高温固相分段反应法制备了尖晶石LiMn2O4和Mg2 掺杂的Li1-xMgxMn2O4(x=0.05、0.1)材料,对材料进行了XRD结构分析和电化学性能等测试,结果表明:Mg2 掺杂样品Li1-xMgxMn2O4(x=0.05、0.1)仍保持尖晶石相Fd3m结构;循环性能明显改善,室温条件下50次循环后,样品Li0.9Mg0.1Mn2O4的放电容量为100mAh/g,容量保持率为9.9%,而LiMn204容量衰减率仅为18.1%.     

A High-Performance Hybrid Biofuel Cell with a Honeycomb-Like Ti3C2Tx/MWCNT/AuNP Bioanode and a ZnCo2@NCNT Cathode for Self-Powered Biosensing

This work focusses on developing a hybrid enzyme biofuel cell-based self-powered biosensor with appreciable stability and durability using murine leukemia fusion gene fragments (tDNA) as a model analyte. The cell consists of a Ti₃C₂T_x/multiwalled carbon nanotube/gold nanoparticle/glucose oxidase bioanode and a Zn/Co-modified carbon nanotube cathode. The bioanode uniquely exhibits strong electron transfer ability and a high surface area for the loading of 1.14 × 10⁻⁹ mol cm⁻² glucose oxidase to catalyze glucose oxidation. Meanwhile, the abiotic cathode with a high oxygen reduction reaction activity negates the use of conventional bioenzymes as catalysts, which aids in extending the stability and durability of the sensing system. The biosensor offers a 0.1 fm –1 nm linear range and a detection limit of 0.022 fm tDNA. Additionally, the biosensor demonstrates a reproducibility of ≈4.85% and retains ≈87.42% of the initial maximal power density after a 4-week storage at 4 °C, verifying a significantly improved long-term stability.     

A Cascade Enzyme System Integrating Peroxidase Mimic with Catalase for Linear Range Expansion of H2O2 Assay: A Mechanism and Application Study

Peroxidase (POD) Nanozyme-based hydrogen peroxide (H₂O₂) detection is popular, but hardly adapt to high concentration of H₂O₂ owing to narrow linear range (LR) and low LR maximum. Here, a solution of combining POD and catalase (CAT) is raised to expand the LR of H₂O₂ assay via decomposing part of H₂O₂. As a proof of concept, a cascade enzyme system (rGRC) is constructed by integrating ruthenium nanoparticles (RuNPs), CAT and graphene together. The rGRC-based sensor does perform an expanded LR and higher LR maximum for H₂O₂ detection. Meanwhile, it is confirmed that LR expansion is closely associated with apparent K_m of rGRC, which is determined by the relative enzyme activity between CAT and POD both in theory and in experiment. At last, rGRC is successfully used to detect high concentration of H₂O₂ (up to 10 mm ) in contact lens care solution, which performs higher assay accuracy (close to 100% recovery at 10 mm of H₂O₂) than traditional POD nanozymes. This study brings up a kind of POD/CAT cascade enzyme system and provides a new concept for accurate and facile H₂O₂ detection. Additionally, it replenishes a new enzyme-substrate model of achieving the same pattern with competitive inhibition in enzyme reactions.     

Tailoring Advanced N-Defective and S-Doped g-C3N4 for Photocatalytic H2 Evolution

Although challenges remain, synergistic adjusting various microstructures and photo/electrochemical parameters of graphitic carbon nitride (g-C₃N₄) in photocatalytic hydrogen evolution reaction (HER) are the keys to alleviating the energy crisis and environmental pollution. In this work, a novel nitrogen-defective and sulfur-doped g-C₃N₄ (S-g-C₃N₄-D) is designed elaborately. Subsequent physical and chemical characterization proved that the developed S-g-C₃N₄-D not only displays well-defined 2D lamellar morphology with a large porosity and a high specific surface area but also has an efficient light utilization and carriers-separation and transfer. Moreover, the calculated optimal Gibbs free energy of adsorbed hydrogen (ΔG_H*) for S-g-C₃N₄-D at the S active sites is close to zero (≈0.24 eV) on the basis of first-principle density functional theory (DFT). Accordingly, the developed S-g-C₃N₄-D catalyst shows a high H₂ evolution rate of 5651.5 µmol g⁻¹ h⁻¹. Both DFT calculations and experimental results reveal that a memorable defective g-C₃N₄/S-doped g-C₃N₄ step-scheme heterojunction is constructed between S-doped domains and N-defective domains in the structural configuration of S-g-C₃N₄-D. This work exhibits a significant guidance for the design and fabrication of high-efficiency photocatalysts.     

氮化硼纳米片负载纳米Cu2O及其催化还原对硝基苯酚

纳米级氧化亚铜具有高效的催化性能, 但较差的稳定性使其应用受限。本研究采用简单可控的抗坏血酸液相还原及气氛焙烧法, 制备了一种兼具高催化活性与催化稳定性的Cu₂O/BNNSs-OH负载型催化剂, 其中以聚乙烯吡咯烷酮(PVP)与水相变提供的“推-拉”作用剥离的氮化硼纳米片(BNNSs)为载体, 液相还原反应体系pH=11时, 抗坏血酸向Cu ²⁺滴定制备的Cu₂O纳米颗粒(2~7 nm)为活性组分。通过扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、傅里叶变换红外光谱仪(FT-IR)及拉曼(Raman)光谱仪等对样品的形貌和结构进行表征, 结果表明: Cu₂O纳米粒子不但高度分散于载体表面, BNNSs对Cu₂O还有一定的稳定作用, 避免其被氧化成CuO。将Cu₂O/BNNSs-OH应用于对硝基苯酚催化还原反应中, 该催化剂表现出同贵金属类似的高催化活性, 5次重复利用后的转化率仍高达90%。     

A Magnetofluorescent Carbon Dot Assembly as an Acidic H2O2‐Driven Oxygenerator to Regulate Tumor Hypoxia for Simultaneous Bimodal Imaging and Enhanced Photodynamic Therapy

Recent studies indicate that carbon dots (CDs) can efficiently generate singlet oxygen (¹O₂) for photodynamic therapy (PDT) of cancer. However, the hypoxic tumor microenvironment and rapid consumption of oxygen in the PDT process will severely limit therapeutic effects of CDs due to the oxygen‐dependent PDT. Thus, it is becoming particularly important to develop a novel CD as an in situ tumor oxygenerator for overcoming hypoxia and substantially enhancing the PDT efficacy. Herein, for the first time, magnetofluorescent Mn‐CDs are successfully prepared using manganese(II) phthalocyanine as a precursor. After cooperative self‐assembly with DSPE‐PEG, the obtained Mn‐CD assembly can be applied as a smart contrast agent for both near‐infrared fluorescence (FL) (maximum peak at 745 nm) and T₁‐weighted magnetic resonance (MR) (relaxivity value of 6.97 mM^?1 s^?1) imaging. More interestingly, the Mn‐CD assembly can not only effectively produce ¹O₂ (quantum yield of 0.40) but also highly catalyze H₂O₂ to generate oxygen. These collective properties of the Mn‐CD assembly enable it to be utilized as an acidic H₂O₂‐driven oxygenerator to increase the oxygen concentration in hypoxic solid tumors for simultaneous bimodal FL/MR imaging and enhanced PDT. This work explores a new biomedical use of CDs and provides a versatile carbon nanomaterial candidate for multifunctional nanotheranostic applications.     

可磁分离回收多孔CoFe_(2)O_(4)的制备及其催化过一硫酸盐降解亚甲基蓝溶液的性能EI北大核心CSCD

采用草酸盐热解法制得Fe_(2)O_(3),Co_(3)O_(4)以及CoFe_(2)O_(4)三种过渡金属氧化物多孔材料。借助XRD,SEM,BET,VSM和XPS等测试手段对材料的晶体结构、微观形貌、比表面积、磁学性能以及表面化学状态进行分析。选择典型的阳离子型染料亚甲基蓝(MB)作为降解模型,对三种样品催化活化过一硫酸盐(PMS)降解处理模拟印染废水的性能进行评价。结果表明:三种材料均具有分级微/纳米纤维状多孔结构,CoFe_(2)O_(4)因具有最大的比表面积以及Fe,Co元素间的协同效应比Fe_(2)O_(3)和Co_(3)O_(4)表现出更为优异的催化PMS降解MB溶液的性能。通过单因素实验,确定出CoFe_(2)O_(4)/PMS体系降解500 mL浓度为10 mg·L^(-1)MB溶液的优化条件为:PMS用量3 mL(0.1 mol·L^(-1)),催化剂添加量0.07 g,反应时间50 min。在此条件下,MB的降解去除率为89.77%。考察几种阴离子对CoFe_(2)O_(4)/PMS催化氧化体系的影响,发现Cl^(-),PO_(4)^(3-),C_(2)O_(4)^(2-)的存在均对MB的降解有一定的抑制作用。活性物种猝灭实验和电子顺磁共振(EPR)鉴定结果证实,^(1)O_(2)是CoFe_(2)O_(4)/PMS催化氧化体系中产生的最主要活性物种。循环使用实验结果表明,CoFe_(2)O_(4)具有较好的稳定性,且可磁分离回收特性使其可作为活化PMS降解印染废水的候选催化材料。     

Self‐Assembled Nanostructured CuCo2O4 for Electrochemical Energy Storage and the Oxygen Evolution Reaction via Morphology Engineering

CuCo₂O₄ films with different morphologies of either mesoporous nanosheets, cubic, compact‐granular, or agglomerated embossing structures are fabricated via a hydrothermal growth technique using various solvents, and their bifunctional activities, electrochemical energy storage and oxygen evolution reaction (OER) for water splitting catalysis in strong alkaline KOH media, are investigated. It is observed that the solvents play an important role in setting the surface morphology and size of the crystallites by controlling nucleation and growth rate. An optimized mesoporous CuCo₂O₄ nanosheet electrode shows a high specific capacitance of 1658 F g⁻¹ at 1 A g⁻¹ with excellent restoring capability of ≈99% at 2 A g⁻¹ and superior energy density of 132.64 Wh kg⁻¹ at a power density of 0.72 kW kg⁻¹. The CuCo₂O₄ electrode also exhibits excellent endurance performance with capacity retention of 90% and coulombic efficiency of ≈99% after 5000 charge/discharge cycles. The best OER activity is obtained from the CuCo₂O₄ nanosheet sample with the lowest overpotential of ≈290 mV at 20 mA cm⁻² and a Tafel slope of 117 mV dec⁻¹. The superior bifunctional electrochemical activity of the mesoporous CuCo₂O₄ nanosheet is a result of electrochemically favorable 2D morphology, which leads to the formation of a very large electrochemically active surface area.     

纳米磷酸铁包覆锂离子电池正极材料LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2的制备及其电化学性能

为改善LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2正极材料的电化学性能,采用自制的磷酸铁纳米悬浮液,通过共沉淀法在LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2正极材料表面包覆纳米磷酸铁。应用XRD,TG-DTA,TEM等手段表征制备的磷酸铁的结构,形貌和液相状态;通过XRD,SEM,EDS,TEM,ICP,恒流充放电、循环伏安、交流阻抗表征制备的包覆材料的结构、形貌及电化学性能。研究烧结温度和包覆量对LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2正极材料电化学性能的影响。结果表明,热处理温度为400℃,2%(质量分数,下同)磷酸铁包覆能显著地改善LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2正极材料的循环性能和倍率性能。循环伏安和交流阻抗结果显示,包覆磷酸铁后改善了LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2正极材料的可逆性和动力学性能。ICP测试结果表明,磷酸铁包覆层能够有效地降低电解液对正极材料的溶解与侵蚀,稳定其层状结构,从而提高正极材料的电化学性能。