A bismuth-rich Bi4O5Br2/TiO2 composites fibers photocatalyst enables dramatic CO2 reduction activity
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摘要: 光催化CO2还原技术既能实现节能减排,又能缓解能源短缺,符合当今绿色可持续发展的理念。本工作以静电纺丝技术制备的TiO2纳米纤维为基质,结合水热还原法制备Bi@Bi4O5Br2/TiO2复合纤维。利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(HRTEM)、X射线光电子能谱(XPS)、紫外-可见吸收光谱(UV-Vis)和碳吸附等方法对其微观结构、形貌和光学性能进行表征。结果表明:TiO2 纳米纤维经Bi4O5Br2复合后,光谱响应范围拓展到可见光区,光生电子还原能力增强,可以将CO2还原成CH4和CO;金属Bi的富集不仅能提高催化剂对酸性CO2分子的吸附能力,增强CO2转化效率,而且能改变光催化反应路径,并有醇类物质(CH3OH)的生成。模拟太阳光照射3 h,Bi@Bi4O5Br2/TiO2光催化CO2还原生成CH4、CO和CH3OH的速率分别达到3.87、1.06和0.32 μmol·h−1·g−1。本研究为探索高效二氧化碳光还原催化剂提供了新的机会。
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关键词:
- 富Bi /
- Bi4O5Br2/TiO2复合纤维 /
- 光催化 /
- CO2还原 /
- 静电纺丝
Abstract: Photocatalytic reduction technology of CO2 can not only achieve energy saving and emission reduction, but also alleviate energy shortage, which is in line with today's concept of green and sustainable development. By employing electrospun TiO2 nanofibers as substrate, bismuth- rich Bi4O5Br2/TiO2 composite fibers were prepared combining with in-situ hydrothermal reduction method. The composition, morphology and photoelectric properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electronmicroscopy (HRTEM), X-ray photoelectric spectroscopy (XPS), ultraviolet-visible absorption spectrum (UV-vis) and carbon adsorption. The results show that the band gap of Bi4O5Br2/TiO2 composite fibers becomes width, there is obvious absorption in the visible light band, and the reduction ability of photogenerated electrons is enhanced. Bi4O5Br2/TiO2 composite fibers can reduce CO2 to CH4 and CO, while the enrichment of the metal Bi can not only improve the adsorption capacity of the catalyst for acidic CO2 molecules and enhance the conversion efficiency, but also change the photocatalytic reaction path and generate alcohol products such as CH3OH. The CH4, CO and CH3OH yields of the optimized photocatalyst Bi@Bi4O5Br2/TiO2 composite fibers were 3.87, 1.06 and 0.32 μmol·h−1·g−1, respectively, after simulated sunlight irradiation 3 h. This work paves new opportunities for exploring high-efficiency CO2 photoreduction catalysts.-
Key words:
- Bismuth-rich /
- Bi4O5Br2/TiO2 composite fibers /
- Photocatalytic /
- CO2 reduction /
- Electrospinning
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图 4 样品TiO2、Bi4O5Br2、Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2的 CO2 吸附等温线(a)和样品Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2的CO2程序升温脱附(b)
Figure 4. CO2 adsorption isotherms of TiO2、Bi4O5Br2、Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2for the samples (a) and temperature programmed desorption spectrum of CO2 for the samples Bi4O5Br2/TiO2 and Bi@Bi4O5Br2/TiO2 (b)
图 6 样品TiO2、Bi4O5Br2、Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2的:(a)紫外-可见漫反射,(b)光致发光和(c)瞬态光电流;Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2的瞬态荧光衰减寿命(e);TiO2和Bi4O5Br2的莫特肖特基曲线(f)
Figure 6. UV-Vis DRS (a), PL spectra (b) and Transient photocurrent responses(c) of TiO2,Bi4O5Br2,Bi4O5Br2/TiO2 and Bi@Bi4O5Br2/TiO2 samples; (e) Transient fluorescence decay lifetime of Bi4O5Br2/TiO2 and Bi@Bi4O5Br2/TiO2 samples; Mott-Schottky curve (f) of TiO2 and Bi4O5Br2 samples
图 7 样品TiO2、Bi4O5Br2、Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2光催化CO2还原3小时后CH4、CO和CH3OH的生成速率(a)及样品Bi@Bi4O5Br2/TiO2光催化产物的生成量随时间变化图(b)
Figure 7. Yields of CH4,CO and CH3OH for photocatalytic CO2 reduction over TiO2, Bi4O5Br2, Bi4O5Br2/TiO2 and Bi@Bi4O5Br2/TiO2 samples after 3 hours irradiation (a). Time course of the products in the photocatalytic conversion of CO2 over Bi@Bi4O5Br2/TiO2 sample (b)
表 1 样品TiO2、Bi4O5Br2、Bi4O5Br2/TiO2和Bi@Bi4O5Br2/TiO2的比表面积、孔径和孔容大小
Table 1. Specific surface area, pore size, pore volume size of TiO2, Bi4O5Br2, Bi4O5Br2/TiO2 and Bi@Bi4O5Br2/TiO2 samples
Sample Specific
surface area/
(m2·g−1)Average pore
diameter/nmTotal pore
volume/
(cm2·g−1)TiO2 30 14.6 0.15 Bi4O5Br2 128 20.4 0.24 Bi4O5Br2/TiO2 144 24.9 0.26 Bi@Bi4O5Br2/TiO2 132 21.6 0.25 表 2 CO2光催化还原产物生成速率比较
Table 2. Comparison of products generation rate for CO2 photocatalytic reduction
Photocatalyst Illumination
period/(h)Reaction
conditionProduct Yield
(μmol·g−1·h−1)Reference Pt/D–TiO2–x 5 300 W Xe lamp
120℃, waterCH4 0.34 Nanoscale
2020 Ref.[29]Fe–TiO2 12 Visible light
(λ>400 nm)CH4 7.73 Micropor Mesopor Mat
2020 Ref.[30]TiO2–G 5 300 W Xe lamp
NaHCO3+H2SO4CO
CH45.20
26.7J Catal
2019 Ref.[31]Fe/TiO2/rRGO 5 300 W Xe lamp
(λ>420 nm)CH4
O24.08
4.32Earth Env Sci
2020 Ref.[32]Bi2Al4O9/β–Bi2O3 10 300 W Xe lamp
H2OCO 13.5 Green Energy Environ
2021 Ref.[33]Bi/Bi4O5Br2 2 300 W high pressure xenon lamp CO
CH43.16
0.50Nano Energy
2019 Ref.[34]g-C3N4/α-Fe2O3 300 W Xenon lamp CH3OH 5.63 J CO2 Util
2019 Ref.[35]TiO2/(NiOH)2 3 300 W Xe lamp
40 mW cm−2CO
CH4
CH3OH
CH3CH2OH0.71
2.20
0.58
0.37J. Mater. Chem. A
2018 Ref.[8]Notes: D—diameter; G—graphene; rGO—reduced graphene oxide -
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