Degradation of rhodamine B photocatalyzed by Eu-doped CdS nanowires illuminated by visible radiation

CdS nanowires doped with different contents of Eu dopant were synthesized by solvothermal method. XRD, SEM, TEM and Raman analyses certified that the as-synthesized samples were hexagonal CdS uniform nanowires. The pure CdS nanowires were 1–3 ?μm long and 80 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 298 and 594 ?cm^?1. The 3% Eu-doped CdS wires were 800 ?nm–2.5 ?μm long and 75 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 296 and 593 ?cm^?1. CdS nanowires grew along the [001] direction due to the surface energy effect. The photocatalytic properties of CdS and Eu-doped CdS nanowires were investigated for the degradation of rhodamine B (RhB) illuminated by visible radiation. In this research, Eu dopant played the role in promoting the photocatalytic kinetics because Eu³⁺ ions act as an electron acceptor to promote charge separation and photocatalytic activity. Both ^●OH and ^●O₂^? were the main active radicals used to transform RhB molecules into CO₂, H₂O and other intermediates.     

钒钨酸盐-CdS纳米粒子复合膜的制备与电致变色性能

通过层-层自组装方法制备了由Dawson结构三钒取代型钨酸盐1-K₉P₂W₁₅V₃O₆₂·18H₂O(P₂W₁₅V₃)与CdS纳米粒子构筑的复合膜材料, 研究了CdS纳米粒子添加和复合膜层数对P₂W₁₅V₃多酸复合膜材料电致变色性能的影响. 采用UV, XRD, SEM和循环伏安等测试手段对复合材料的结构和性能进行了表征; 将电化学工作站和紫外-可见吸收光谱联用, 在-1.0~+1.0 V的电压范围内, 对不同层数、 有无CdS纳米粒子复合的的膜材料的电致变色性能进行研究. 研究结果表明, 20层的复合膜材料性能最佳, 光反差为38.05%, 着色时间为3.57 s, 褪色时间为6.94 s, 最大着色效率达到94.04 cm²/C, 实现了从无色、 蓝色到蓝紫色, 再到无色的可逆颜色变化, 相对于单独P₂W₁₅V₃膜, 光反差提高46.07%, 着色效率提高96.53%, 电致变色性能显著提高.     

Structure transition and photoluminescence of CdS/Si nanoheterostructure array on thermal annealing

CdS/Si heterojunctions have been prepared through growing CdS nanocrystallites (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) by the chemical bath deposition method. Cadmium nanocrystallites (nc-Cd) have been observed and ascribed to the reducibility of Si-NPA. The reason for the appearance of CdO is indistinct and the related work will be done in the future. The blue, green and red emissions are ascribed to the silicon oxide layer, band gap of nc-CdS and the sulphur vacancies, respectively. Redshift and blueshift with the annealing temperature about green emissions are contributed to quantum size effect and the structure transition from nc-Cd to CdO. It is beneficial for investigating the structures and defects to the application of CdS/Si in the optoelectronic field.     

硫化镉反蛋白石光子晶体制备及光解水制氢

对硫化镉反蛋白石结构光子晶体薄膜进行了可控合成,用巯基乙酸修饰的纳米晶和P(St-MMA-SPMAP)高分子小球共组装,成功地构筑了反蛋白石结构并用于可见光光解水产氢。结果表明,在可见光(λ≥420 nm)照射下,Cd S-310反蛋白石结构薄膜的光解水产氢性能比硫化镉纳米颗粒提高了一倍。这主要是因为等级孔结构反蛋白石光子晶体特性对催化剂的光催化性能的提升:首先,反蛋白石的周期性结构增加了光子在材料中的传播,提高了催化剂对太阳光的利用率;同时,大孔孔壁是由纳米颗粒堆积而成的,在反应中提供了更多的反应活性位点;此外,孔结构有利于物质的传输和分子的吸附。     

New glass ceramics: an effective conjunction of wet chemistry synthesis and sintering

A glass with CdS nanoparticles was used simultaneously as a matrix for Ce-doped garnet and a yellow-red phosphor to prepare luminescent glass ceramics for the sources of white light. CdS nanoparticles compensate for the unbalanced Ce³⁺ emission spectrum of the composite material due to the addition of a red component. The synthesized composite material can be a tunable light converter due to altered luminescence spectra by changing the sintering conditions and excitation wavelength     

Synthesis and characterization of ternary nanocomposites of TiO2/rGO/CdS as an efficient catalyst for photo-degradation of methyl orange

Novel ternary composite photocatalysts have been successfully prepared by TiO₂ nanofibers, reduced graphene oxide, and CdS nanoparticles (TiO₂/rGO/CdS) by using electrospinning technique with easy chemical methods. The structures and their properties are examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscope (FESEM). The structural characterization of the composite reveals that pure TiO₂ NFs and CdS NPs crystalline very well and the reduced graphene oxide is tightly composed with TiO₂ NFs and CdS Nps. The photodegradation of methyl orange (MO) under UV light illumination is significantly enhanced compared with that of bare materials. This ternary composite degrades methyl orange within 75 min. The enhanced photocatalytic degradation performance resulted from effective separation of e–h pairs with rGO sheets and also contributed for high rate degradation efficiency. This novel ternary composite has a potential application of wastewater purification and utilization for energy conversions.     

超薄骨架有序介孔CdS/NiS的制备及光催化产氢性能

采用有序介孔氧化硅为硬模板, 通过纳米浇筑法制备了由螺旋骨架构建的有序介孔硫化镉(CdS)光 催化材料. 该光催化材料具有约5 nm厚的超薄骨架和大的比表面积(238 m²/g), 能有效缩短光催化反应中 光生电荷迁移到表面进行反应的距离并同时提供更多的反应活性位点, 从而增强光催化性能. 通过原位化学沉积法将不同量的助催化剂硫化镍(NiS)沉积到有序介孔CdS表面, 得到了一系列超薄骨架有序介孔CdS/NiS复合光催化材料. 可见光照射下的光催化产氢活性测试结果表明, 负载适量NiS的有序介孔CdS具有显著增强的光催化产氢活性(3.84 mmol?h^-1?g^-1), 约为负载相同量NiS的普通商业化CdS材料(0.22 mmol?h^-1?g^-1)的17.5倍.     

Simultaneous photoelectrochemical detection of dual microRNAs by capturing CdS quantum dots and methylene blue based on target-initiated strand displaced amplification

Herein,we propose a novel photoelectrochemical(PEC) biosensor for dual microRNAs(miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification(SDA) reaction.The recognition of H_(miR-21) and H_(let-7 a) by microRNA-21 and let-7 a leads to their change in hairpin structures,subsequently initiating the immobilization of abundant CdS quantum dots(CdS QD s) and methylene blue(MB) based on SDA reaction.The immobilized CdS QDs and MB produce both high PEC currents under430 nm light and 627 nm light illumination,respectively,and the generated PEC currents are closely relied on target miRNAs amounts.Thus,highly sensitive and simultaneous detection of microRNA-21 and let-7 a was readily achieved with detection limit at 6.6 fmol/L and 15.4 fmol/L based on 3σ,respectively.Further,this PEC biosensor was applied in simultaneous analysis of miRNA-21 and let-7 a in breast cancer patient's serum with acceptable results.We expect this biosensor will find more useful application in diagnosis of miRNA-related diseases.     

Photovoltammetric behavior and photoelectrochemical determination of p-phenylenediamine on CdS quantum dots and graphene hybrid film

A photoelectroactive film composed of CdS quantum dots and graphene sheets (GS) was coated on F-doped SnO₂ (FTO) conducting glass for studying the electrochemical response of p-phenylenediamine (PPD) under photoirradiation. The result indicated that the cyclic voltammogram of PPD on CdS–GS hybrid film became sigmoidal in shape after exposed under visible light, due to the photoelectrocatalytic reaction. Such a photovoltammetric response was used to rapidly optimize the photoelectrocatalytic activity of hybrid films composed of different ratios of CdS to GS toward PPD. The influences of scan rate and pH on the photovoltammetric behavior of PPD on CdS–GS film revealed that although the controlled step for electrochemical process was not changed under photoirradiation, more electrons than protons might participate the photoelectrocatalytic process. Furthermore, the photoelectroactive CdS–GS hybrid film was explored for PPD determination based on the photocurrent response of film toward PPD. Under optimal conditions, the photocurrent signal on CdS–GS film was linearly proportional to the concentration of PPD ranging from 1.0 × 10⁻⁷ to 3.0 × 10⁻⁶ mol L⁻¹, with a detection limit (3S/N) of 4.3 × 10⁻⁸ mol L⁻¹. Our work based on CdS–GS hybrid film not only demonstrated a new facile photovoltammetric way to study the photoinduced electron transfer process of PPD, but also developed a sensitive photoelectrochemical strategy for PPD determination.