BiVO_(4)表面氧空位的调控及其光降解抗生素研究

Study on the regulation of surface oxygen vacancies in BiVO_(4) and photodegradation of antibiotics

通过水热法一步合成了BiVO_(4)催化剂,并在氩气气氛下对BiVO_(4)催化剂进行表面改性。通过SEM、TEM、XRD、XPS和PL对BiVO_(4)催化剂进行分析表征,结果表明BiVO_(4)催化剂及改性BiVO_(4)催化剂为单斜状的晶体结构,且改性BiVO_(4)催化剂表面含有大量的氧空位。相比BiVO_(4)催化剂,氧空位BiVO_(4)催化剂的价带由1.97 eV增加至2.13 eV,扩大了带隙,降低了电子和空穴的复合率。在抗生素磺胺甲唑(SMX)初始质量浓度为10 mg/L,考察了不同因素对氧空位BiVO_(4)催化剂光催化降解SMX的影响,结果表明最佳反应条件为氧空位BiVO_(4)催化剂投加量50 mg/L,反应温度35℃,光照度150 mW/cm^(2),pH 5.0~9.0。此外,研究表明氧空位BiVO_(4)催化体系能够抵御水体中常见阴离子的干扰,但受到腐殖酸的抑制较为明显。对氧空位BiVO_(4)光催化降解SMX进行了机理分析,相对于BiVO_(4)光催化体系,氧空位BiVO_(4)体系产生了更多的活性物质,包括O_(2)^(·-)、·OH和h^(+),氧空位降低了电子和空穴复合率,提高了BiVO_(4)的光催化活性,增强了对SMX的降解速率。整体上,氧空位的调控是提高光生载流子分离率、提高光催化剂活性的有效策略。

BiVO_(4) catalyst was synthesized in one step by hydrothermal method,and the surface modification of BiVO_(4) catalyst was carried out in argon atmosphere.The BiVO_(4) catalyst was characterized by SEM,TEM,XRD,XPS and PL.The results showed that the BiVO_(4) catalyst and the modified BiVO_(4) catalyst had monoclinic crystal structure,and the surface of the modified BiVO_(4) catalyst contained a large number of oxygen vacancies.Compared with BiVO_(4) catalyst,the valence band of oxygen vacancy BiVO_(4) catalyst increased from 1.97 eV to 2.13 eV,which enlarged the band gap and decreased the recombination rate of electrons and holes.When the initial mass concentration of antibiotic sulfamethoxazole(SMX)was 10 mg/L,the effects of different factors on the photocatalytic degradation of SMX with oxygen vacancy BiVO_(4) catalyst were investigated.The results showed that the optimal reaction conditions were 50 mg/L with oxygen vacancy BiVO_(4) catalyst,35℃,150 mW/cm^(2) and pH 5.0-9.0.In addition,the common anions in water had less interference to the BiVO_(4) catalytic system of oxygen vacancy,but the inhibition of humic acid was more obvious.The mechanism of photo catalytic degradation of SMX by oxygen vacancy BiVO_(4) was analyzed.Compared with the BiVO_(4) photo catalytic system,the oxygen vacancy BiVO_(4) system produced more active substances,including O_(2)^(·-),·OH and h^(+).The oxygen vacancy reduced the electron and hole recombination rate,improved the photocatalytic activity of BiVO_(4) and enhanced the degradation rate of SMX.On the whole,the regulation of oxygen vacancy is an effective strategy to improve the photogenerated carrier separation rate and the activity of photocatalyst.