【大学化学】doi: 10.12461/PKU.DXHX202409084
在现在这个人人爱美的年代,护肤品已经成为我们生活中不可缺少的助手,而SOD蜜就是其中一种我们所熟知的护肤品,其中起关键作用的物质是超氧化物歧化酶(SOD)。本实验基于SOD的作用机理,设计实验探索了SOD清除超氧自由基从而延缓皮肤衰老的奥秘,同时揭示了辅料二甲基硅油和硬脂酸甘油酯如何协助SOD顺利穿透皮肤表面角质层的作用机理。通过本科普实验的展示与互动,能够让受众学习到SOD蜜各成分的作用机制、表面张力作用、表面活性剂的乳化作用等内容,让大家感受到无处不在的化学知识,激发人们对化学学习和探索的兴趣。
【无机化学学报】doi: 10.11862/CJIC.20240255
采用原位聚合法制备了氯氧化铋(BiOCl)与聚苯胺(PANI)复合的Ⅱ型异质结光催化剂BiOCl/PANI,并采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis DRS)和N2吸附-脱附测试等多种技术手段对其进行了表征,考察了BiOCl/PANI在模拟可见光下对罗丹明B (RhB)的光催化降解性能。实验结果表明:BiOCl/PANI催化剂比PANI和BiOCl具有更高的光催化活性,在RhB质量浓度为50 mg·L-1、PANI与BiOCl的物质的量之比为0.02∶1、50 mg·L-1的催化剂条件下,所制备的BiOCl/PANI光催化150 min后,RhB降解率为98.8%,速率常数为0.031 min-1;经过4次循环实验后,RhB降解率从98.8%降低至98.4%,表现出良好的稳定性和可重复利用性。光催化剂BiOCl/PANI实现了电子和空穴对的快速分离,降低了二者在催化剂内部的复合速率,提高了光催化性能。
【大学化学】doi: 10.12461/PKU.DXHX202405147
仪器分析实验“分子荧光法测定罗丹明B的含量”存在实验过于简单、未考虑实际情况等问题。因此,本改进实验在三维荧光扫描模式下获取样本数据,不进行复杂预处理,而是运用化学计量学算法解析出目标分析物的纯信号,进而实现了染色辣椒中罗丹明6G和123的同时测定。本改进实验提高了学生全面考虑问题和创新解决问题的能力。
【物理化学学报】doi: 10.3866/PKU.WHXB202403008
电化学硝酸根还原反应(eNO3–RR)合成氨是一种可持续的将环境污染物转化为高附加值产品的方法。钯基双金属纳米催化剂作为高效催化剂已显示出巨大的前景,但调控其组成和构型以提高催化性能并实现深入的机理理解仍然很有挑战。通过使用不同供/吸电子官能团的两个配体,我们成功地制备了两个原子精确的(AgPd)27双金属团簇,即Ag18Pd9(C8H4F)24 (简称Ag18Pd9)和Ag22Pd5(C9H10O2)26 (简称Ag22Pd5)。两个团簇的金属核具有明显不同组成和构型,其中Ag18Pd9为中间层是9个Pd原子的“三明治”型金属核结构,Ag22Pd5为M13构型组成的棒状金属核结构,而5个钯原子位于M13构型的顶点和中心位置。出乎意料的是,Ag22Pd5表现出明显优于Ag18Pd9的eNO3−RR性能。具体表现来说,Ag22Pd5在−0.6 V时NH3的法拉第效率和产生速率达到最高,分别为94.42%和1.41 mmol·h−1·mg−1,但Ag18Pd9的NH3的最高法拉第效率和产生速率只有在−0.5 V时的43.86%和0.41 mmol·h−1·mg−1。原位衰减全反射表面增强红外光谱(ATR-SEIRAS)测试提供了反应中间体的实验证据,从而揭示了反应途径,也表明Ag22Pd5比Ag18Pd9具有更强的NO3–吸附和NH3脱附能力。理论计算表明,配体脱落的团簇可以暴露AgPd双金属位点,Ag-Pd位点为协同催化活性位点,不同构型的AgPd活性位点有显著差异,其中Ag22Pd5中的活性位点更有利于NO3−吸附和NH3脱附,从而加速催化过程。
【无机化学学报】doi: 10.11862/CJIC.20240219
A simple two-step hydrothermal method synthesized four different CdS/Fe3O4 photocatalysts with varying ratios of mass of CdS to Fe3O4. The composition and morphology of the prepared samples were investigated using X-ray diffraction (XRD), Raman spectrum, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Solid UV reflectance spectra testing found that CdS/Fe3O4 nanocomposites had good light absorption throughout the spectral range, promoting their photocatalytic properties. Under visible light irradiation, CdS/Fe3O4 (2:5) with a mass ratio of 2:5 exhibited excellent photocatalytic performance, with a degradation rate of 98.8% for rhodamine B. Furthermore, after five cycles of photocatalytic degradation reaction, the rhodamine B degradation rate remained at 96.2%, indicating that the photocatalysts have good photocatalytic stability.
【无机化学学报】doi: 10.11862/CJIC.20250028
A flower-like BiOBr photocatalyst (CS/BiOBr) was prepared by using the carbon material derived from corn straw (CS) as the carrier. The prepared composites were characterized by X - ray diffraction (XRD), Fourier transform infrared (FIIR) spectra, scanning electron microscope (SEM), X - ray photoelectron spectra (XPS), and UV-Vis diffuse reflectance spectra (UV-Vis DRS). The SEM analyses indicate that the introduction of CS promotes the formation of a unique flower-like structure in BiOBr, which not only optimizes the efficiency of light capture but also increases the specific surface area of BiOBr. The bandgap of the composite was narrower compared with the pure BiOBr. The CS/BiOBr composites exhibited higher photocatalytic activity than pure CS and BiOBr under visible light irradiation, and a higher first-order reaction rate constant (k) of 0.043 7 min-1 than BiOBr (0.014 6 min-1), and exhibited excellent stability and reusability during the cyclic run. The enhanced photocatalytic activity is attributed to the efficient separation of photoinduced electrons and holes. Superoxide radicals and holes were the major active species.
【大学化学】doi: 10.3866/PKU.DXHX202308095
基于向大一学生开设的“电解-量气法测定阿伏加德罗常数”实验,设计了Cu2O的电化学合成及量气法测定阿伏加德罗常数一体化实验,该实验巧妙地融合了元素化学实验中有关Cu2O的制备及性质实验内容。一次电解完成两个实验,节约电能,节省时间。Cu2O的电化学合成及量气法测定阿伏加德罗常数一体化实验可作为一个微实验灵活穿插于大学基础化学实验教学中,对于培养大一学生的全方位思考的意识和多角度分析问题的能力以及经济、环保的理念有重要意义。