锌掺杂BiOBr合成及可见光下对CO2光催化还原机理

Synthesis of Zn-Doped BiOBr with Enhanced Photoreduction CO2 Activity under Visible Light Irradiation

溴氧化铋(BiOBr)半导体已被应用于光催化CO2还原,但其活性仍然极低。通过简单的水热法合成了Zn-BiOBr光催化剂,并在可见光照射下研究其对CO2催化效果。结果表明,合成的Zn-BiOBr样品在可见光照射下具有比原BiOBr更高的光催化还原CO2转化活性,其对CO2光催化还原速率最高可达到8.49μmol·h^-1,是原BiOBr的13倍。同时,我们亦对光催化活性增强机理进行了研究,发现在可见光照射下,Zn-BiOBr半导体被激发,产生光致电子空穴对,光诱导电子有效还原CO2,生成CO。锌的掺杂为BiOBr提供了更合适的带边位置和能带缺陷,降低了光生电子与空穴对的复合速率,大大提高了光催化还原CO2的能力。

The bismuth oxybromide(BiOBr)semiconductor has been used in photocatalytic CO2 reduction for a long time,but the catalytic activity remains low.Herein,the Zn-doped BiOBr photocatalysts(called Zn-BiOBr)was synthesized by a simple hydrothermal method,which put out higher catalytic activity than pure BiOBr under visible light.The results showed that the synthesized 2% Zn-BiOBr exhibited the highest photocatalytic rate of 8.49μmol·h^-1,which was 13 times higher than pure BiOBr.The enhancement mechanism of photocatalytic activity was also studied.Under visible light,Zn-BiOBr catalyst is excited and creates photo-induced electrons and holes,which effectively improve the conversion of CO2 into CO.Doping of zinc provides BiOBr with a more suitable band gap and energy band defects,facilitates the separation of photogenerated charges,and reduces the recombination rate of photogenerated electrons,all of which contribute to the CO2 conversion efficiency.