Photodegradation of rhodamine B over semiconductor supported gold nanoparticles: The effect of semiconductor support identity

Rhodamine B (RB) is a toxic dye used extensively in textile industry, which must be remediated before its drainage to environment. In the present study, supported gold nanoparticles on commercially available titania and zincite were successfully prepared and then their activity on the photodegradation of RB under UV A light irradiation was evaluated. The synthesized photocatalysts were characterized by ICP, BET, XRD, TEM and EDX. Kinetic results showed that Au/TiO₂ was a photocatalyst inferior to Au/ZnO. This observation could be attributed to the strong reflection of UV irradiation by gold nanoparticles over TiO₂ support.     

Structure Tuning of Bi2MoO6 and Their Enhanced Visible Light Photocatalytic Performances

Structure-tuning strategies for synthesis and modification of Bi₂MoO₆, a novel visible light photocatalyst, have progressed at a quick pace. The enhancement of photocatalytic performances has been obtained through several morphology controls including hierarchical structures and heterojunctional nanocomposites. In this article, various structure modifications and their structural advantages in photocatalysis will be reviewed. In the first section, the structures of Bi₂MoO₆ such as crystal structures, electronic structures, and band structures will be presented. In the second section, many controllable synthesis approaches for modification of Bi₂MoO₆, including solid-state reaction, co-precipitation, solvothermal, and hydrothermal methods will be introduced. In the last section, the enhancement of photocatalytic activity for Bi₂MoO₆ due to the structure tuning will be discussed. The comprehensive review will provide perspectives on the research of efficient photocatalysts under visible light irradiation.     

氮自由基化学新进展:光催化N-H键活化途径

氮自由基作为一种高活性的中间体,为新型化学反应的设计及含氮化合物的合成提供了新的机遇.光催化条件活化N-H键直接产生氮自由基具有绿色、高效、经济等优点,相关方法学的研究在近年来取得了重要进展.本综述就2016年至今报道的几例最新的研究成果进行亮点评述.     

可见光促进的双键三氟甲基化反应研究

报道了一种可见光促进的双键直接三氟甲基化的方法.研究中利用Ru（bpy）₃Cl₂为催化剂,Togni's试剂为三氟甲基来源,在可见光促进下实现了含羰基烯烃的三氟甲基化.该反应具有方法简便,条件温和,可以获得较高的反应收率,同时避免了有毒试剂的使用.     

Modulating the properties of monolayer C_2N: A promising metal-free photocatalyst for water splitting

Photocatalytic water splitting has gained increasing attention, since it utilizes renewable resources, such as water and solar energy, to produce hydrogen. Using the first-principles density functional theory, we investigate the properties of the single layer C_2N which was successfully synthesized. We reveal that monolayer C_2N has a substantial direct band gap of 2.45 eV. To regulate its band gap, four different nonmetal elements(B, O, P, and S) on the cation and anion sites are considered. Among them, B-doped N site is the most effective one, with the lowest formation energy and a band gap of 2.01 eV. P-doped N site is the next, with a band gap of 2.08 eV, though its formation energy is higher. The band alignments with respect to the water redox levels show that, for these two dopings, the thermodynamic criterion for the overall water splitting is satisfied. We therefore predict that B-or P-doped C_2N, with an appropriate band gap and an optimal band-edge position, would be a promising photocatalyst for visible-light water splitting.     

ZnO-SiO2的制备及其光催化降解罗丹明B

采用溶胶-凝胶法制备负载型ZnO-SiO2光催化材料,研究升温速率及负载量对ZnO结构、形貌及光催化活性的影响.通过X射线衍射、N2物理吸附-脱附、扫描电子显微镜、光致发光光谱和紫外-可见漫反射光谱等手段对催化剂进行表征,并以罗丹明B为模拟污染物,紫外光为光源,评价催化剂活性.结果表明,升温速率对ZnO-SiO2光催化剂结晶度和光催化活性影响显著.当ZnO与SiO2的质量比为1∶1时,ZnO-SiO2具有均匀、平滑的球形形貌,并且ZnO光催化活性明显改善.     

介孔碳负载Ce-TiO2的制备及其光催化降解亚甲蓝性能

以Ce(NO3)3·6H2O、一水合柠檬酸、2-羟基对苯二甲酸、N,N-二甲基甲酰胺(DMF)、钛酸四丁酯为原料,通过水热法获得一种新型的Ce-Ti金属有机材料前驱体,将该前驱体在不同烧结温度下煅烧,获得一系列具有高比表面积的介孔碳负载Ce-TiO2新型催化剂.应用XRD、SEM、BET、TG、UV-vis DRS、UV紫外吸收等一系列手段对其进行了结构表征与性能测量.研究结果表明烧结温度在1000 ℃(CTOF-P10)的样品表现出良好的催化效果,其降解亚甲蓝(MB)的速率是商业型TiO2(P25)的2.15倍.引入Ce离子起到掺杂的作用,同时阻止TiO2晶粒的生长,也能抑制光生电子与空穴的复合,进而提高了光催化活性.     

ZnWO4-ZnO复合光催化剂的制备及光催化性能

以ZnO及WO3为前驱反应物,制备了一系列不同ZnWO4含量的ZnWO4-ZnO复合光催化剂.利用X射线衍射、扫描电子显微镜及X射线能谱仪等手段对催化剂进行表征,并以紫外光为光源,罗丹明B为模拟污染物,评价催化剂的活性.结果表明,热处理温度及ZnWO4与ZnO摩尔比对催化剂光催化降解罗丹明B的活性影响显著.当复合4mol;ZnWO4,并于850 ℃煅烧所制得的ZnWO4-ZnO催化剂活性最高,比纯ZnO高出25;.这是因为ZnWO4的复合可抑制ZnO晶粒长大,提高光生电子与空穴的分离效率,进而改善其光催化活性.     

Efficient photocatalytic degradation of Acid Red 57 using synthesized ZnO nanowires

Zinc oxide photocatalyst was synthesized through a low‐temperature co‐precipitation process using zinc sulfate as precursor for the degradation of Acid Red 57 (AR57) under UV irradiation. The activities of the prepared photocatalyst at different calcination temperatures (400, 500, and 600 °C) were investigated. The synthesized zinc oxides were characterized by different techniques such as X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, N₂ adsorption–desorption, and pH titration for the determination of the zero‐point charge (pH_ZPC). The efficiency of photocatalytic degradation of ZnO prepared at the calcination temperatures of 400, 500, and 600 °C was 90.03, 77.67, and 72.71%, respectively, after 190 min. The kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of AR57 fitted first‐order kinetics and the OH^? radicals were the main species. During irradiation, the formation of OH^? free radicals was ascertained by photoluminescence studies using terephthalic acid as the probe molecule.     

Carbon nanotubes/TiO2 nanotubes composite photocatalysts for efficient degradation of methyl orange dye

A series of carbon nanotubes/TiO2 nanotubes （CNTs/TNTs） composite photocatalysts were successfully prepared by incorporation of CNTs in HNO3 washing process. These photocatalysts were characterized by XRD, N2 physical adsorption, UV-vis diffuse reflectance spectroscopy, TEM and Raman spectroscopy, respectively, and their photocatalytic activities were tested by using methyl orange （MO） as a model compound. Also, the effects of amount of CNTs incorporated, calcination temperature and amount of catalyst on the photocatalytic activity of the composite photocatalyst were systematically investigated. The results show that the CNTs/TNTs composite exhibits much higher photocatalytic activity than that of the TNTs or CNTs alone.