NF-Bi2O3/SBA可见光催化还原Cr(Ⅵ)
Photocatalytic reduction of Cr(Ⅵ) by NF-Bi2O3/SBA under visible light
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摘要: 本文以分子筛SBA-15为载体,预先吸附Bi (NO3)3,然后与NH4F均匀混合,一步煅烧法制备了可见光响应型NF-Bi2O3/SBA.研究发现,高温煅烧时,吸附在SBA上的Bi (NO3)3分解形成Bi2O3.与此同时,NH4F分解生成的HF优先刻蚀SBA,生成的NH3优先掺入Bi2O3晶格.Bi2O3负载在SBA-15上比表面积显著提升,共存NH4F能对Bi2O3进行N、F共掺杂改性,进一步窄化带隙,提升可见光响应,并调控Bi2O3的晶面结构,得到均匀片状的NF-Bi2O3,最终促进电子-空穴对的分离和传递.与Bi2O3、NF-Bi2O3和Bi2O3/SBA相比,NF-Bi2O3/SBA具有最佳的可见光催化活性,光催化还原Cr (Ⅵ)的速率常数是Bi2O3体系的6.3倍.Abstract: In this paper, Bi(NO3)3 was pre-adsorbed on molecular sieve SBA-15, followed by uniform mixing with NH4F. After one-step calcination, visible-light-responsive NF-Bi2O3/SBA was obtained. It was found that Bi(NO3)3 pre-adsorbed on SBA decomposed into Bi2O3 when calcined at high temperature. Meanwhile, HF generated by NH4F decomposition preferentially etched SBA, while NH3 was preferentially doped into the lattice of Bi2O3. The specific surface area was significantly increased after loading Bi2O3 onto SBA-15. The coexistence of NH4F led to N, F co-doping of Bi2O3 with narrowed band-gap. In this way, the visible-light-response was enhanced, and the crystal structure of NF-Bi2O3 can be tuned with uniform sheet shape. Finally, the separation and transfer of photo-generated electron-hole pairs were promoted. Compared with Bi2O3, NF-Bi2O3 and Bi2O3/SBA, NF-Bi2O3/SBA obtained optimal visible light activity, and the photocatalytic rate for Cr(Ⅵ) reduction was 6.3 times that on Bi2O3.
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Key words:
- Bi2O3 /
- SBA-15 /
- N-F codoping /
- visible-light photocatalysis /
- Cr (Ⅵ)
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