Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid on TiO2 films under UVA and UVB irradiation
Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid on TiO2 films under UVA and UVB irradiation
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DOI：
10.1007/s10800-005-1397-1
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发表时间：
2005-07-01
影响因子：
2.9
通讯作者：
McAdams, ET
中科院分区：
文献类型：
--
作者：
McMurray, TA;Byrne, JA;McAdams, ET
二氧化钛(TiO2光催化)是一种可能的替代/补充净水技术。提高这一过程的整体效率的尝试包括使用更高能量的紫外线来获得更好的量子效率，以及通过施加外部电势来电化学辅助这一过程。本工作采用在硼硅酸盐玻璃和掺铟氧化锡(ITO)硼硅酸盐玻璃上制备的纳米二氧化钛薄膜，研究了UVA和UVB照射下甲酸的光催化和电化学辅助光催化氧化。实验在具有高传质特性的搅拌釜式反应器中进行。UVB照射下的甲酸氧化速率比UVA照射下的高30%。在开路或+1.0V(SCE)电压下，在100%O-2的UVA照射下，最大pH(APP)为9%。在100%O-2的UVB照射下，二氧化钛在硼硅酸盐玻璃上的最大PHI(APP)为20.3%。在紫外光照射下，ITO硼硅酸盐玻璃上的二氧化钛在+1.0V、100%O-2时的PHI(APP)为19%。UVB的氧化速率和PHI(APP)的增加是由于二氧化钛在较短波长的较高消光系数和/或导带电子促进到更高更稳定的状态，从而降低了载流子的复合速率。与使用UVA源相比，使用UVB源可显著提高氧化速率和增加表观量子产率，但需要对该过程进行成本分析，以确定使用UVB源的经济可行性。在存在传质限制的大型反应器中，电化学辅助光催化可能是有益的。
Titanium dioxide (TiO2) photocatalysis is a possible alternative/complementary technology for water purification. Attempts to increase the overall efficiency of the process include using higher energy UV to gain better quantum efficiency and electrochemically assisting the process by the application of an external electrical potential. In this work, nanocrystalline TiO2 films, prepared on borosilicate glass and indium-doped tin oxide (ITO) borosilicate glass, were used to investigate the photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under UVA and UVB irradiation. The experiments were carried out in a stirred tank reactor with high mass transfer characteristics. The rate of formic acid oxidation under UVB irradiation was 30% greater as compared to UVA irradiation. A maximum Phi(app) of 9% was obtained under UVA irradiation in 100% O-2 under open circuit or +1.0 V (SCE) applied potential. A maximum Phi(app) of 20.3% was obtained under UVB irradiation with 100% O-2 using TiO2 on borosilicate glass. Phi(app) was 19% for +1.0 V, 100% O-2, using TiO2 on ITO borosilicate glass under UVB irradiation. The increase in oxidation rates and Phi(app) with UVB irradiation are due to the higher extinction coefficient of TiO2 at shorter wavelengths and/or the promotion of conduction band electrons to higher more stable states, thus reducing the rate of recombination of charge carriers. The use of a UVB source as compared to a UVA source results in a significant increase in the rate of oxidation and increased apparent quantum yields, however, a cost analysis of the process would be required to determine the economic viability of employing UVB sources. Electrochemically assisted photocatalysis may prove beneficial in large-scale reactors where mass transfer limitations exist.