摘要
采用电沉积法制备了离子液体[Emim]BF_4改性PbO_2电极。通过电化学氧化降解苯酚实验对电极催化性能进行了考察,发现苯酚模拟废水的COD去除率符合一级反应动力学,[Emim]BF_4改性PbO_2电极的速率常数为0.007 39 min^(-1),明显高于未改性PbO_2电极的速率常数0.003 83 min^(-1)。采用SEM、XRD、XPS对电极表面结构进行表征。结果显示,[Emim]BF_4改性钛基PbO_2涂层表面致密规整、结晶度高、晶格氧含量高。通过莫特-肖特基曲线、稳态极化和线性扫描伏安法考察了电极的电化学性质。结果表明,改性电极表面氧空位含量相比未改性电极大大降低,改性电极的析氧过电位相比未改性电极有明显提高。通过与未改性电极结构和电化学性质的对比研究,得出改性电极催化活性的提高主要是由于其氧空位含量较低,从而降低了氧化物电极表面羟基自由基(·OH)向晶格氧(O_(lat))转移的发生率。
Modified PbO_2 electrodes were prepared by electrodeposition in the presence of ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate（[Emim]BF_4）. The electro-catalytic performance of the prepared electrodes for the electrochemical degradation of phenol in aqueous solution was investigated. The COD removal of phenol simulated wastewater followed pseudo-first-order rate kinetics. The rate constant with [Emim]BF_4-modified PbO_2 electrodes was 0.007 39 min-1, higher than 0.003 83 min^（-1 ）obtained with non-modified PbO_2 electrodes. The microstructure of the electrodes was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties were investigated by Mott-Schottky, steady-state polarization and linear sweep voltammetry techniques. Results indicate that PbO_2 coatings with compact and regular morphology, a higher degree of crystallinity and higher content of oxygen in crystal lattice are anodically grown on Ti substrate from electrolyte containing [Emim]BF_4. Steady-state polarization tests show that oxygen evolution overpotential on modified electrodes is significantly higher than that on non-modified ones. Mott-Schottky tests reveal a markedly lower content of oxygen vacancy in modified PbO_2 samples as compared with the non-modified ones. It is suggested that the enhanced electro-catalytic activity of the [Emim]BF_4-modified PbO_2 electrodes towards phenol degradation arises largely from its lower content of oxygen vacancy, which decreases the probability of oxygen transferring from more effective ·OH into less desirable Olatat the electrode surface.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2017年第7期1833-1838,共6页
Rare Metal Materials and Engineering
基金
National Natural Science Foundation of China(51278407,51478379,51408468)
