新型可见光催化剂BiVO4的制备方法

作为一种新型可见光催化剂,钒酸铋（BiVO₄）因为拥有较窄的禁带宽度（2.4eV）以及合适的导带和价带位置在可见光催化领域受到广泛关注,在水的光解以及有机污染物的降解等方面都有研究及应用。不同的制备方法对材料的形貌和结构都有较大的影响,进而影响到光催化剂的光催化性能。综述了国内外BiVO₄的制备方法,并在此基础上展望了该领域的发展方向。     

柠檬酸络合法制备可见光响应型光催化剂CuO/BiVO4

以Bi（NO3）3·5H2O和NH4VO3为原料,采用柠檬酸络合法制备新型可见光响应型复合光催化剂CuO/BiVO4。借助X射线衍射、全谱直读等离子体发射光谱仪、X射线光电子能谱仪、扫描电子显微镜、透射电子显微镜和紫外–可见漫反射光谱等表征粉体的结构和性能。结果表明：不同Cu摩尔掺量的复合光催化剂仍保持纯单斜晶系白钨矿...     

Thermoelectric power of ferroelectric potassium vanadate,cesium vanadate,lithium vanadate and their solid solutions

The thermoelectric power of the vanadates of potassium, cesium and lithium and their solid solutions was measured in the temperature range covering their transition points. The thermoelectric power measurement was carried out by the two-electrode technique for pellets of polycrystalline ceramic samples. The thermoelectric power increased with temperature initially, then decreased attaining a zero value at the transition temperature. As the concentration of KVO₃ increased the thermoelectric power decreased for the solid solutions (K _x − Cs_1−x )VO₃, whereas the thermoelectric power increased with increase in concentration of KVO₃ for the solid solutions (K _x − Li_1−x )VO₃. Vanadates of potassium, cesium, and lithium and their solid solutions showedP type semiconductor behaviour in ferroelectric state andn type semiconductor behaviour in paraelectric region.     

FeVO4 as a highly active heterogeneous Fenton-like catalyst towards the degradation of Orange II

The iron vanadate, FeVO₄, was prepared and characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). It was found that FeVO₄ could effectively catalyze H₂O₂ to generate active hydroxyl radical OH, which was confirmed with electron spin resonance (ESR) spin-trapping technique. Therefore, it was employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the degradation efficiency of Orange II. Compared with the conventional heterogeneous Fenton-like catalysts, α-Fe₂O₃, Fe₃O₄ and γ-FeOOH, FeVO₄ possessed a much higher catalytic activity. The high catalytic activity possibly involved in a special two-way Fenton-like mechanism, that is, the activation of H₂O₂ by both Fe(III) and V(V) in FeVO₄. Moreover, FeVO₄ possessed a wide applicable pH range and its catalytic activity was slightly affected by the solution pH values in the range of 3–8.     

煅烧烧型Mg／Al—CO3双金属氧化物对水溶液中钒酸根离子的脱除

采用共沉淀法合成Mg/Al摩尔比为2：1的层状双金属氢氧化物Mg/Al-LDH,并在500℃下煅烧6 h得到煅烧双金属氢氧化物Mg/Al-CLDH。研究Mg/Al-CLDH对钒酸根的吸附性能,探讨镁铝摩尔比、吸附剂用量、溶液初始浓度、时间和温度等因素对吸附效果的影响,并对其吸附过程的动力学和热力学过程进行研究。研究表明：Mg/Al-CLDH 对钒酸根的吸附效果很好。该吸附过程符合准一级动力学方程,平衡吸附等温线很好地符合Langmuir方程,并且Langmuir方程拟合常数高达0.999。通过热力学计算发现ΔGΘ为负值,ΔHΘ为正值,表明此吸附本质上是吸热自发过程。吸附机理研究表明此吸附主要是表面吸附。     

Optimization of sono-Fenton degradation of Acid Blue 113 using iron vanadate nanoparticles

ABSTRACT

Iron vanadate (FeVO₄) nanoparticles were synthesized by hydrothermal method and used as heterogeneous Fenton-like catalyst in ultrasound (US)-assisted degradation of Acid Blue 113. By using a quadratic response surface model, more than 99% color removal and 80% TOC reduction were obtained using low amounts of catalyst and H₂O₂ at short reaction time and circumneutral pH condition. The synthesized nanocatalyst also exhibited a good reusability under US irradiation. The results indicate that the proposed sono-Fenton-like process is efficient for the treatment of recalcitrant compounds in industrial effluents.     

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％。     

NiO decorated Mo:BiVO4 photoanode with enhanced visible-light photoelectrochemical activity

Photoelectrochemical water splitting has attracted increasing attention recently in the perspective of clean and sustainable energy economy. Herein, we reported the synthesis of NiO functionalized Mo doped BiVO₄ (denoted as NiO/Mo:BiVO₄) nanobelts and their enhanced photoelectrochemical activity for efficient water oxidation. The prepared NiO/Mo:BiVO₄ p–n junction structure showed much higher water splitting activity than the pristine BiVO₄ and Mo:BiVO₄. Such obvious enhancement are due to the increased donor density by doping with Mo and fast separation of the photoexcited electron–hole pairs by the novel p–n junction composite structure. Under light irradiation, photoexcited holes in the conduction band (CB) of Mo:BiVO₄ will conveniently transfer to the p-type NiO with the effect of the inner electric field. Meanwhile, the holes would oxidize the water into oxygen and the electrons transfer to the counter electrode (Pt electrode) to produce hydrogen. This novel p–n junction structure could open up new opportunities to develop high-performance photoanode for water splitting.     

A high-performance ceramic composite anode for protonic ceramic fuel cells based on lanthanum strontium vanadate

The composite electrodes for protonic ceramic fuel cells (PCFC) were fabricated by infiltration of (La_0.8Sr_0.2)FeO_3−δ (LSF) cathode and (La_0.7Sr_0.3)V_0.90O_3−δ (LSV) anode into a porous protonic ceramic, Ba(Ce_0.51Zr_0.30Y_0.15Zn_0.04)O_3−δ (BCZY-Zn), respectively. Further, Pd-ceria catalysts were added into the composite anode. In the same method, the oxygen ion conducting fuel cells with the yttria-stabilized zirconia as an electrolyte (YSZ cell) were also fabricated. At 973 K, the non-ohmic area specific resistance (ASR) of PCFC (0.09 Ω cm²) was much smaller than that of the YSZ cell (0.28 Ω cm²) although the protonic conductivity of BCZY-Zn was slightly smaller than the oxygen ion conductivity of YSZ. According to the analysis of the symmetric cells with BCZY-Zn as an electrolyte, the LSV-composite anode showed better performance than the LSF-composite cathode at low temperatures.     

钒渣钙化焙烧熟料的浸出过程

The process of acid leaching of calcification roasted vanadium slag was studied. The effects of process parameters variation on phase of the vanadium leaching residue, leaching rate of vanadium and the reason of vanadium loss were analyzed. The results showed that the main phase of vanadium leaching residue was insoluble in acid of dense solid solution R2O3 and Fe2TiO5, which was also mixed with silicate pyroxene phase and small amount of vanadate phase. The vanadium leaching rate first increased and then decreased with raising the roasting temperature, roasting time and the CaO/V2O5 mass ratio. Silicate species and its effect on vanadate, spinel oxidation incomplete, vanadium and vanadium bronze solid solution in of R2O3, and the difference of best leaching acidity of Ca3V2O8, Ca2V2O7 and CaV2O6 were the causes of vanadium loss.