pH值对氮掺杂TiO2物化性质和光催化活性的影响

以TiCl4为前驱体,水合肼和氨水的混合溶液为氮源,采用共沉淀法制备了可见光响应型氮掺杂二氧化钛(N-TiO2)光催化剂,重点研究了制备过程中pH值对催化剂的微结构和光催化活性等物化性质的影响.采用XRD、BET、UV-vis和XPS等表征方法对光催化剂性质进行了表征.催化剂主要以锐钛矿相存在,具有介孔结构和较高的比表面积(～90m2/g).随着pH值增大,锐钛矿相(101)面衍射峰逐步增强,晶粒尺寸逐渐增大,比表面积逐渐减小.XPS结果表明催化剂掺杂的氮主要以系列氮氧化物形式存在.氮掺杂小幅降低了禁带宽度,感光范围拓展到可见光区.光催化降解实验表明,pH=3.5时,催化剂的可见光降解效率最高,为39.65%.随着pH值增大,催化剂可见光催化活性逐渐降低;而在紫外光照射下,pH=9.5时,催化活性最低;pH=5.5时,催化活性最高.     

菱形十二面体磷酸银的制备及其可见光催化性能研究

采用离子交换法,通过调控N,N-二甲基甲酰胺(DMF)与H_2O比例,制备出了具有可见光催化活性的菱形十二面体磷酸银。利用X射线衍射仪(XRD)、扫描电镜(SEM)、傅里叶红外光谱(FT-IR)和紫外-可见光谱仪(UV-Vis)等方法对催化剂进行了表征,并且考察了该催化剂的可见光催化性能。结果表明:通过调控DMF/H_2O比制备的菱形十二面体磷酸银晶型完整、形貌规则,对可见光的吸收增强。与无规则磷酸银相比较,菱形十二面体磷酸银表现出了较高的光催化活性,且DMF∶H_2O=5∶15为降解罗丹明B(Rh B)的最佳比例,超氧阴离子(·O_2~-)和空穴(h~+)为参与可见光催化降解Rh B的主要活性物种。     

含氧化合物可见光催化剂的研究进展

简述了可见光光催化机理,指出该机理与紫外光光催化机理的不同之处在于其电荷传输与分离机制。介绍了改性二氧化钛可见光催化剂的研究进展,重点概述了ABO3型、ABO4型和铋系等新型含氧化合物光催化剂的近期研究进展。展望了含氧化合物可见光催化剂在环境净化领域的应用前景。     

银纳米材料的应用进展

随着纳米技术的发展,银纳米材料独特的电学、光学、热学、催化及弹性等性能,使其在表面增强拉曼光谱、透明导电薄膜、催化剂、传感器及抗菌杀菌领域展现出广阔的应用前景。立足于近年来国内外银纳米材料的研究现状和热点问题,重点论述了银纳米材料的应用进展,指出了银纳米材料应用中面临的问题并对其未来的发展趋势进行了展望。     

载银TiO2/SiO2可见光催化降解偶氮染料的研究

用不同的方式制备了一系列载银TiO2/SiO2催化剂,并将其应用于可见光降解偶氮染料AO7,并对催化剂进行了XRD谱、SEM和BET表征.结果表明,Ag 的掺杂对催化剂的活性没有影响,而A0的掺杂能明显促进催化剂的活性,Ag0的最佳浓度为1%.在TiO2/可见光体系中,Ag0对催化剂活性的提高是因为A0加速了电子向溶解氧的转移,从而减少了染料正碳自由基和电子的复合.     

利用可见光催化分解水制氢的研究进展

简述了利用可见光催化分解水制氢的基本原理及该领域的最新研究进展.由能带模型概述了设计可见光响应催化剂的3种方案,重点介绍了元素掺杂类型光催化剂、氮氧/硫氧化物光催化剂、固溶体催化剂等可见光催化分解水体系.阐述了该课题的重要意义及面临的巨大挑战,提出了未来该领域需要加强研究的若干问题.     

溶胶一凝胶法制备钒酸铋及其光催化性能研究

采用溶胶一凝胶法制备钒酸铋颗粒光催化剂,研究银掺杂、煅烧温度、煅烧时间对BiVO4晶型组成和催化活性的影响,用X射线衍射（XRD）、透射电镜进行表征,研究了BiVO4粉体在焙烧过程中的相转变,确定了煅烧温度、煅烧时间及掺杂比例;以甲基橙（MO）的可见光催化降解反应为探针,研究了催化剂的可见光催化性能,研究发现,当煅烧时间为4h,煅烧温度为500℃时,BiV04对甲基橙光催化效率可达约20％。银掺杂的BiVO4对基橙光催化效率可达约40％。     

沉淀法合成蘑菇状AgBr-Ag_3PO_4催化剂及其光催化性能研究

以二甲基甲酰胺(DMF)为辅助剂,以硝酸银(AgNO3)、磷酸二氢钾(KH2PO4)和十六烷基三甲基溴化铵(CTAB)为原料,采用简单的液相沉淀法一步合成蘑菇状纳米溴化银/磷酸银(AgBr/Ag_3PO_4)可见光催化剂,并对样品进行了表征,以甲基橙(MO)溶液(pH=2)为目标降解物研究其光催化性能。研究结果表明:合成的蘑菇状纳米AgBr/Ag_3PO_4可见光催化剂,其禁带宽度为1.97eV,对MO溶液有较好的可见光催化活性;在可见光照4min,0.08g AgBr/Ag_3PO_4对酸性MO溶液(200mL,8mg/L)的降解率达到97.86%,循环降解3次后降解率为95.21%。     

磷酸银/类石墨氮化碳-硅藻土复合材料的制备及可见光催化性能

通过浸渍-焙烧-沉积法制备了一系列磷酸银/类石墨氮化碳-硅藻土复合材料。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis-DRS)等方法对其结构、形貌和光吸收特性进行了表征。以罗丹明B(RhB)为模拟污染物,评估了磷酸银/类石墨氮化碳-硅藻土复合材料在可见光照射下的光催化活性和稳定性。结果表明,与磷酸银/类石墨氮化碳、磷酸银、类石墨氮化碳相比,磷酸银/类石墨氮化碳-硅藻土复合材料表现出优异的光催化活性。系统地研究了磷酸银含量对光催化活性的影响,发现催化剂A/CD_(8/2)表现出最高的光催化活性,可见光照射21 min后,对罗丹明B的降解率高达98. 61%;循环使用3次后,对罗丹明B的降解率仍然维持在95%,表现出良好的稳定性和重复使用性。光催化活性的提高主要归因于磷酸银/类石墨氮化碳-硅藻土复合材料中光生电子-空穴对的高效分离以及吸附/光催化协同效应。     

新型可见光响应型BiVO_4光阳极的研究进展

BiVO4是一种新型可见光型半导体催化剂,在环境催化领域表现出了出色的催化性能。综述了近年来BiVO4光阳极材料的最新研究进展,重点阐述了国内外优化BiVO4性能以提高太阳能利用率的最新方法,并指出实际应用亟待解决的问题和未来的研究方向。     

银基钎料在制造业中的研究进展

钎料的性能很大程度上决定了钎焊接头的质量和钎料的应用范畴.银基钎料作为一类非常重要的硬钎焊材料,其填缝能力优异,强度与黄铜、低碳钢接近,可钎焊除铝、镁合金等轻金属之外的所有金属材料.因此,银基钎料广泛应用于航空航天、超硬工具等制造领域,并且受到国内外钎焊界学者们的高度关注.然而,银基钎料的发展及应用过程中仍存在以下问题:第一,钎料中贵金属银含量偏高(一般高于45%),导致钎料使用成本高;第二,银基钎料挤压、轧制、拉拔等加工过程中不可避免地存在夹杂物,影响钎料的使用性能和连接质量;第三,有益金属或合金调控钎料及其连接性能的机制较为复杂,尚未完全研究清楚;第四,传统制备银基钎料的方法产能低下;第五,银基钎料在制造业领域的应用研究尚未见系统报道.国内外对于银基钎料钎焊性能及工程应用方面的研究主要集中于:(1)开发多种节银降银钎料,主要是有益元素调控银基钎料连接性能方面的研究;(2)改进钎料的传统加工方法,提出新的制造方法,如粉末电磁压制成形、钎焊过程中原位合成、快速凝固、镀覆扩散组合等;(3)研究杂质元素(C、Ca、S、Al、Fe、Bi、Pb、O、N 等)的影响;(4)银基钎料形态创新研究,如三明治复合钎料(中间为铜合金、两边为银钎料)、箔带钎料、镀锡银钎料等;(5)工程应用研究,银基钎料在航空航天、汽车制造、电力能源等工业领域起着不可替代的作用,但目前国内外仍缺乏系统阐述该方面研究的报道.因此,本文对近20年国内外有关银基钎料的研究报道进行了评述,重点讨论了合金元素对银基钎料性能的影响.首先对银基钎料研究现状进行详述,总结了Cu、Zn、Sn、Ga、In、Ni、Mn、Cd、Li、Ce、La、P、Si、Pr在银基钎料中的优缺点,归纳了杂质元素C、S、O、N、Ca、Al、Fe、Pb、Bi的恶化作用.其次对银基钎料在航空航天、汽车制造、电力能源、超硬工具、家用电器、眼镜行业等制造业中的应用研究进行详细介绍.最后提出银基钎料研究和应用中的不足,为银基钎料的深入系统研究及相关技术发展提供理论指导.     

复相增强AgMeO电触头材料的研究进展

由于良好的抗电弧侵蚀性、抗熔焊性及耐电磨损性,AgMeO电触头材料在电器工业中得到了广泛应用。目前,单一强化相增强银基电触头材料的研究已经基本成熟,但很难提高其综合性能;虽然复相增强银基电触头材料的研究尚不够深入,但已经表现出巨大的研究潜力,因此复相增强银基电触头材料成为研究热点。本文概述了复相增强银基电触头材料的研究现状与成果,同时对复相增强电触头材料的发展方向进行了展望。     

Design of Heterostructured Hollow Photocatalysts for Solar‐to‐Chemical Energy Conversion

Direct conversion of solar energy into chemical energy in a sustainable manner is one of the most promising solutions to the energy crisis and environmental issues. Fabrication of highly active photocatalysts is of great significance for the practical applications of efficient solar‐to‐chemical energy conversion systems. Among various photocatalytic materials, semiconductor‐based heterostructured photocatalysts with hollow features show distinct advantages. Recent research efforts on rational design of heterostructured hollow photocatalysts toward photocatalytic water splitting and CO₂ reduction are presented. First, both single‐shelled and multishelled heterostructured photocatalysts are surveyed. Then, heterostructured hollow photocatalysts with tube‐like and frame‐like morphologies are discussed. It is intended that further innovative works on the material design of high‐performance photocatalysts for solar energy utilization can be inspired.     

银基填充复合材料电磁屏蔽效能研究

银基填充复合材料作为电磁屏蔽材料是电磁屏蔽领域研究热点之一。选用片状银粉、环氧树脂及固化剂制备导电银胶,使用涂抹棒将导电银胶均匀涂覆于聚酯基板上,固化后测试其各频率波段电磁屏蔽性能。研究了银基填充复合材料膜厚在不同波段电磁屏蔽性能的差别,测试其体积电阻率,通过扫描电镜观察横截面中片状银粉分散的均匀性,推导其电磁屏蔽机理。     

Recent progress in oxynitride photocatalysts for visible-light-driven water splitting

Photocatalytic water splitting into hydrogen and oxygen is a method to directly convert light energy into storable chemical energy, and has received considerable attention for use in large-scale solar energy utilization. Particulate semiconductors are generally used as photocatalysts, and semiconductor properties such as bandgap, band positions, and photocarrier mobility can heavily impact photocatalytic performance. The design of active photocatalysts has been performed with the consideration of such semiconductor properties. Photocatalysts have a catalytic aspect in addition to a semiconductor one. The ability to control surface redox reactions in order to efficiently produce targeted reactants is also important for photocatalysts. Over the past few decades, various photocatalysts for water splitting have been developed, and a recent main concern has been the development of visible-light sensitive photocatalysts for water splitting. This review introduces the study of water-splitting photocatalysts, with a focus on recent progress in visible-light induced overall water splitting on oxynitride photocatalysts. Various strategies for designing efficient photocatalysts for water splitting are also discussed herein.     

Recent progress in oxynitride photocatalysts for visible-light-driven water splitting

Abstract

Photocatalytic water splitting into hydrogen and oxygen is a method to directly convert light energy into storable chemical energy, and has received considerable attention for use in large-scale solar energy utilization. Particulate semiconductors are generally used as photocatalysts, and semiconductor properties such as bandgap, band positions, and photocarrier mobility can heavily impact photocatalytic performance. The design of active photocatalysts has been performed with the consideration of such semiconductor properties. Photocatalysts have a catalytic aspect in addition to a semiconductor one. The ability to control surface redox reactions in order to efficiently produce targeted reactants is also important for photocatalysts. Over the past few decades, various photocatalysts for water splitting have been developed, and a recent main concern has been the development of visible-light sensitive photocatalysts for water splitting. This review introduces the study of water-splitting photocatalysts, with a focus on recent progress in visible-light induced overall water splitting on oxynitride photocatalysts. Various strategies for designing efficient photocatalysts for water splitting are also discussed herein.     

Effect of metal oxide precursor on sintering shrinkage, microstructure evolution and electrical properties of silver-based pastes

Since the shrinkage behavior of silver-based films has been correlated with the characteristics of oxide additives used, the relative role of metal oxides and metal-organic precursors in sintering shrinkage and microstructure evolution of silver films was investigated and compared in this work. Films with an oxide powder additive exhibit two-stage shrinkage behavior in contrast to one-stage continuous shrinkage, which occurs in silver films with metal-organic precursors, added. Furthermore, metal-organic precursors are less effective than metal oxide powders in reducing shrinkage of silver-based films. That can be reasonably explained that metal-organic precursors can be effectively decorated around silver powder to inhibit the sintering densification. The Zr-based organic precursor among the metal-organic precursors exhibits optimal retardation in sintering densification of silver film, which is probably interrelated to refractory characteristics of ZrO₂. The unique conductivity and grain growth of silver film with 1.0 wt% tungsten-organic precursor added was possibly due to the partial dissolution of W into Ag.     

A comparison of the wettability of copper-copper oxide and silver-copper oxide on polycrystalline alumina

The contact angles of liquid silver-copper oxide/alumina and liquid copper-copper oxide/alumina systems were determined using the sessile drop method. Copper oxide (CuO) additions of 1.5–10.0 wt% were made. Temperatures of 970–1250 °C for the silver-based alloys and 1090–1300 °C for the copper-based alloys were studied. Minimum contact angles of 42±8 and 64±7 ° were obtained for the copper-copper oxide alloys and the silver-copper oxide alloys, respectively. The contact angle was approximately constant for the silver-copper oxide alloy within the immiscible liquid composition range. While the contact angles were higher for the silver-based alloys relative to the copper-based alloys, successful infiltration of a porous alumina sample was achieved at only 1050 °C for a Ag-10 wt% CuO alloy. Compression tests on infiltrated samples revealed similar compressive strengths for alumina samples infiltrated with silver-copper oxide alloys, silver-copper-copper oxide alloys and copper-copper oxide alloys. The compressive fracture strength for the infiltrated samples was an order of magnitude higher than the fracture strength of the porous alumina body without infiltration. Although silver-based alloys are more expensive than comparable copper-based alloys, in many applications the additional cost may be offset by lower processing or brazing temperatures, improved thermal and electrical conductivity, and improved toughness.     

Fe、N共掺杂改性TiO2/AC复合光催化剂的制备及气相污染物降解性能

采用Sol-gel法制备了Fe、N离子共掺杂改性TiO₂/AC复合光催化剂,利用SEM、XRD、UV-Vis分光光度计对其结构及性能进行了表征。通过对气相甲苯、丙酮和甲醛的光催化降解实验,系统评价了离子掺杂量、抑制剂种类、TiO₂负载量、污染物起始浓度、污染物种类和催化剂循环使用次数对其性能的影响。结果表明,TiO₂以颗粒状镶嵌在AC孔隙内,且主要以锐钛矿相存在,Fe、N离子共掺杂实现了催化剂的可见光响应;确定最佳催化剂制备工艺为Fe、N离子共掺杂量8%、HAc为抑制剂、TiO₂负载量20%。催化剂对甲苯的降解率随起始浓度的增加而增加;催化剂对甲苯和丙酮的降解率较高（约为90%）,对甲醛的降解率较低（约为35%）;循环使用6次后,对甲苯的降解率仍高于P-25（商业纳米TiO₂）。     

无机抗菌剂研究发展及新产品开发

介绍了国内外无机抗菌剂如银系抗菌剂、钛系抗菌剂的研究现状及发展动态 ,着重评述了最新开发的氯制剂类无机抗菌剂 (BMH)的性质、特点 ,讨论了目前无机抗菌剂制备和应用存在的问题 ,并指出了它们可能的发展方向。