氮化碳介孔材料的合成、改性及研究进展

氮化碳介孔材料(MCN)因其保留了石墨相氮化碳优良的物理化学性质外,同时还具有高比表面积和高比孔容积而受到人们的广泛关注。利用金属元素,非金属元素,有机染料,无机半导体材料等对氮化碳介孔材料进行改性,通过软模板、硬模板和无模板法制备氮化碳介孔材料,使其在光催化,气体吸收等领域具有良好的应用前景。主要介绍MCN的合成方法,改性手段以及应用领域,最后展望了氮化碳介孔材料未来发展方向。     

复合还原剂合成β-Sialon材料的研究

选用低品位的铝土矿(Al2O3含量为68wt％)利用复合还原剂碳/硅、碳/铝、铝/硅还原氮化合成β-Sialon.计算试样烧成后的质量变化率,利用检测仪器XRD、SEM、EDS,化学分析法,研究了三种复合还原剂还原氮化低品位铝土矿合成β-Sialon的反应过程、显微结构和相对含量.结果表明:利用三种复合还原剂还原氮化合成β-Sialon材料的机理、生成β-Sialon的相对含量、结晶形貌、生产成本均不同;反应基本结束的温度均为1500℃,生成z值为3左右β-Sialon;工业生产中利用碳/硅复合还原氮化低品位铝土矿合成β-Sialon材料较理想.     

氮化碳的制备及其缺陷调控材料综合教学实验设计

石墨相氮化碳因其化学结构和性能稳定、可见光吸收光谱宽、无毒、廉价等优点,在光催化研究中备受关注.本实验综合采用熔融盐反应法煅烧得到高结晶七嗪环结构的氮化碳(CCN),并对其进行局部缺陷化处理获得D-CCN,使用多种技术对材料的结构进行了表征,并对其光解水产氢性能进行了测试.本实验能让学生了解氮化碳的制备和缺陷调控工艺,...     

硬度仅次于金刚石的氮化碳镀层材料

硬度仅次于金刚石的氮化碳镀层材料美国伊利诺斯西北大学的一个研究组声称已研制出硬度仅次于金刚石的镀层材料氮化碳（ＣＮ）。他们认为ＣＮ的工业用途可能比金刚石镀层更广泛，并认为他们是首次制成结晶ＣＮ的研究组。制成的ＣＮ是亚稳态的。处于气相的ＣＮ很稳定，但其...     

煤矸石在高温材料中的应用研究进展

围绕煤矸石在高温材料领域的应用和研究现状,概述了煤矸石的分类、化学组成及主要矿物成分高岭石的结构特征.分析了煤矸石经过氧化和非氧化气氛下的高温煅烧过程和反应机理,可以充分利用煤矸石中Al2O3、SiO2、有机碳三种主要成分合成耐火材料和陶瓷.阐述了煤矸石通过碳热还原氮化反应合成Saloon材料及其Sialon复相材料的研究成果和进展,为煤矸石的综合利用、提高产品附加值和品位提供了一个重要途径和研究方向.     

华南理工利用三聚氰胺制造光电材料

日前从华南理工大学获悉,该校材料科学与工程学院2009级本科生张远浩,利用三聚氰胺合成了多色发光的光电材料。相关成果发表在《自然》杂志子刊《科学报告》上。据介绍,类石墨层状结构氮化碳由于其优异的光电性能,成为材料科学领域的研究热点。在华南理工大学发光材料与器件国家重点实验室副教授董国平和教授邱建荣的指导下,张远浩等利用廉价的三聚氰胺作为原料,通过简单温和的低温热聚合方法,合成了类石墨层状结构的碳氮化合物,并发现了类石墨层状结构氮化碳的可调谐发光。     

氨基修饰片状氮化碳的制备及光催化性能

石墨相氮化碳是一种低成本易获得的可见光响应光催化剂,但由于比表面积小、光生载流子易复合等缺点限制了其应用。为克服传统氮化碳的缺陷,本实验以尿素和三聚氰胺为原料,通过水热预处理改性前体,再用高温煅烧法成功制备出氨基修饰片状氮化碳光催化材料。并通过X射线衍射（XRD）、扫描电子显微镜（SEM）和X射线光电子能谱仪（XPS）等手段对样品的晶格结构和形貌特征等进行表征。结果表明,成功引入氨基基团的片状氮化碳,比表面积增加且光生载流子复合率显著降低。以罗丹明B和壬基酚溶液的光降解考察材料光催化性能,发现氨基修饰片状氮化碳对其去除率分别为80.69%和50.7%,分别是传统块状氮化碳的2.45倍和2.19倍,是未修饰片状氮化碳的1.26倍和1.21倍。且氨基修饰片状氮化碳材料重复使用5次后仍具有较高光催化活性,光催化性能显著提高。     

多元复合石墨相氮化碳/磷酸银光催化性能研究进展

石墨相氮化碳/磷酸银材料是一种很好的可见光光催化剂,但仍存在一些挑战和问题,限制了其实际应用能力。本文梳理总结了国内外利用银纳米粒子、碳材料、二维层状过渡金属硫化物、支撑材料、磁性Fe_3O_4、其他材料等对石墨相氮化碳/磷酸银复合改性的研究进展,介绍了其制备方法、应用、光催化增强机理等。本综述可以对后期石墨相氮化碳/磷酸银光催化剂的改性研究提供参考。     

电沉积法制备氮化碳晶体

氮化碳是一种比金刚石更坚硬的材料,其拥有广泛的发展和应用前景。文章采取电化学沉积方法,在尿素的甲醇溶液中制备氮化碳,通过引入NaNO3,在单晶硅表面电沉积晶体薄膜,分析了薄膜形成的过程,并用XRD、Raman等手段进行了表征,结果表明,形成的薄膜是一种氮化碳结构,并含有氧元素。     

氮掺杂碳材料的制备及其化学活性位点研究

为了找出比较优异的非铂电极材料,并分析得出其最佳活性位点,分别从氮掺杂碳和碳载过渡金属氮材料催化剂在阴极催化的两个方向进行了探究。现如今通过X射线光电子能谱分析(XPS)可以检测出吡啶型氮、吡咯型氮和石墨型氮三种主要的氮掺杂活性位点。氮掺杂碳(G-N),氮掺杂碳纳米管(NCNT)以及氮掺杂石墨烯-氮掺杂碳纳米管(N-GO1@CNTs2)三种典型的氮掺杂碳材料进行分析。由此可见碳载过渡金属氮催化剂材料的催化活性位点很有可能主要是氮化金属化合物起作用。     

氮化铝陶瓷的制备及其在复合材料中的应用研究

氮化铝(AlN)陶瓷是一种性能优良的高技术陶瓷.本文概述了AlN陶瓷粉体的合成、成形、烧结的制备过程及其在复合材料中的应用研究,指出要更多地开展AlN复合材料及其在复合材料中应用的研究工作,以满足科技发展对材料提出的更高要求.     

Carbon-family materials for flame retardant polymeric materials

As an abundant and attractive element, the emergence of new carbon-based materials brings revolutionary development in material science and technology. Carbon-based materials have spawned considerable interest for fabricating polymer composites/nanocomposites with greatly improved mechanical, thermal, gas barrier, conductivity, and flame retardant performance. In this review, the importance of carbon-based materials and the necessity of fire resistance for polymeric materials are initially introduced. Then, the fundamental flame retardant mechanisms and experimental analytical techniques are described to understand the relationship between structures and flame retardant properties. The main section is dedicated to the preparation and properties of multifunctional polymer composites/nanocomposites with carbon-based materials, with special emphasis on the flame retardant properties of these materials. A wide variety of carbon-based materials are discussed for use in flame retardant polymer nanocomposite, including graphite, graphene, carbon nanotubes, fullerenes as well as some new emerging carbon forms (carbon nitride, carbon aerogels, etc). Finally, a brief outlook at the developments in carbon-based materials for flame retardant polymeric composites is given by discussing the major progress, opportunities, and challenges.     

Two-dimensional graphitic carbon nitride for membrane separation

Recent years, membrane separation technology has attracted significant research attention because of the efficient and environmentally friendly operation. The selection of suitable materials to improve the membrane selectivity, permeability and other properties has become a topic of vital research relevance. Two-dimensional (2D) materials, a novel family of multifunctional materials, are widely used in membrane separation due to their unique structure and properties. In this respect, as a novel 2D material, graphitic carbon nitride (g-C₃N₄) have found specific attention in membrane separation. This study reviews the application of carbon nitride in gas separation membranes, pervaporation membranes, nanofiltration membranes, reverse osmosis membranes, ion exchange membranes and catalytic membranes, along with describing the separation mechanisms.     

聚吡咯/无机纳米粒子复合材料的制备及其电磁屏蔽性能研究进展

综述了聚吡咯（PPy）包覆无机纳米粒子复合材料的主要制备方法及其在电磁屏蔽领域的研究进展,重点讨论了金属单质、氧/碳/氮化物以及碳系材料这三大类无机纳米粒子与PPy复合构成的核壳结构材料的电磁屏蔽性能及相关屏蔽机理。结果表明,核壳结构能够集PPy和无机纳米粒子各自的优势于一体,并发挥二者的协同效应,该方法是制备新型电磁屏蔽材料的一种有效途径。     

Fabrication and mechanical properties of nacre-like alumina with addition of silicon nitride

How to deal with the brittleness of ceramic materials is always one of the hot topics in the field of materials science. Design of layered ceramics with textured structure is one of the effective methods to improve their fracture toughness. The introduction of additives as interlayer phases can balance fracture toughness and flexural strength. However, the research about addition of interlayer phases and their mechanisms in the layered ceramics is still limited. In this work, nacre-like alumina ceramics were successfully fabricated by freeze casting followed by hot pressing. Silicon nitride was incorporated as the interlayer phase, and the effect on the mechanical properties of the nacre-like alumina was investigated. The addition of silicon nitride was beneficial to improvement of interlayer bonding between the alumina layers due to formation of sialon phase, leading to increase of flexural strength but decease of fracture toughness. When the content of silicon nitride was 3.3 wt%, flexural strength and fracture toughness of the sample was 468 MPa and 6.2 MPa m^1/2, respectively. Compared with the sample without silicon nitride, the flexural strength was enhanced significantly. Additionally, both flexural strength and fracture toughness were improved as compared the sample without any additives. This work can provide available references for design and fabrication of high-strength and high-toughness ceramics by properly tuning the layer structure and interlayer phase composition.     

Synthesis and characterization of microporous carbon nitride

This research reports the preparation and characterization of amorphous microporous carbon nitride using HZSM-5 zeolite as template, and ethidene diamine and carbon tetrachloride as chemical precursors. Microporous amorphous carbon nitride is generated by removal of HZSM-5 zeolite in the obtained zeolite/carbon nitride composite using hydrofluoric acid after carbonization the precursor inside the channels of zeolite. The microporous carbon nitride was characterized by nitrogen sorption techniques, scanning electron microscopy, elemental analysis, X-ray diffraction, X-ray photoelectron spectroscopy, IR spectroscopy, Ultraviolet–visible spectroscopy, Raman spectroscopy, and thermo-gravimetric analysis. Amorphous microporous carbon nitride with high surface area and narrow pore size distribution is thermal stable under atmosphere conditions up to 700 K.     

氮化硅陶瓷材料微波烧结研究现状

氮化硅是一种具有优良性能的陶瓷材料,是一种理想的高温结构材料和高速切削刀具材料,近年来随着微波技术的发展,氮化硅的微波烧结越来越受关注。本文简述了氮化硅陶瓷材料传统烧结与微波烧结的研究现状;比较分析了各种烧结技术制备的氮化硅陶瓷的微观结构和力学性能,得出了微波烧结氮化硅陶瓷的优越性;最后提出氮化硅陶瓷微波烧结在未来研究中还需解决的问题。     

Silicon nitride based nanocomposites produced by two different sintering methods

This research explores the use of a variety of carbon nanostructures as reinforcing agents for Si₃N₄ matrix composites. We have chosen highly promising families of carbon materials: multiwall, singlewall carbon nanotubes (MWCNTs, SWCNTs), graphene, carbon black nanograins and graphite micrograins for use as fillers. These materials were dispersed with a concentration of 3 wt% in silicon nitride matrices. A high efficiency attritor mill has also been used for effective dispersion of second phases in the matrix. In the present work the development of sintering processes (hot isostatic pressing (HIP) and spark plasma sintering (SPS)) has been performed to consolidate and tailor the microstructure of Carbon nanotube (CNT)-reinforced silicon nitride-based ceramic composites. The silicon nitride nanocomposite systems retained the mechanical robustness of the original systems. Elastic modulus measurements and micro-indentation investigations of the hardness and fracture toughness have been performed as well as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction in order to characterize the composites produced by the two sintering methods.     

Carbon Nitride-Related Nanomaterials from Chemical Vapor Deposition: Structure and Properties

Nanoscale-sized carbon nitride-related materials exhibit a wealth of interesting structural, electronic, and optical property behaviors. Chemical vapor deposition technology allows almost unlimited freedom to produce films with compositions and structures approaching the nanometer scale among light elements. Aligned polymerized carbon nitride (CN) nanobells have been grown on a large scale and provide excellent field electron emission properties, as described by a side-emission mechanism. Separation of single CN nanobells and fabrication of heterojunctions between CN nanobells and pure carbon nanotubes have been achieved. Boron carbonitride (BCN) nanofibers with controlled orientation and composition have been synthesized; these nanofibers show strong blue-violet photoluminescense at room temperature. Recent progress also has been made on nitrogen-containing diamond, CN, and BCN films. The purpose of this paper is to survey the work that has been conducted and to detail the level of understanding that has been attained in the research on nitride-related materials.