Environmental Engineering Reference
In-Depth Information
Li et al. [203] fabricated an ohmic nanojunction photocatalyst by assembling Cu@Cu
2
O core-shell NPs on TNT arrays. The
prepared photocatalysts show great enhancement in the evolved H
2
rate due to the efficient transfer of photoexcited electrons
and holes. This approach puts forward a facile, low-cost method to improve photocatalytic efficiency and is helpful for exploring
and developing new photocatalysts based on the heterojunction working principle.
3.4
CONClusiONs aNd OutlOOk
Structural characteristics, modification, photocatalytic mechanism, the relationship between structure and photocatalytic
activity, and research progress of Cu
2
O-based nanocomposites for environmental protection are summarized. As a nontoxic,
abundant, high absorption coefficient and theoretical solar cell conversion efficiency semiconductor, Cu
2
O is a potential candidate
in solar energy applications. However, the low efficiency and weak oxidation ability of Cu
2
O hinder its application in photoca-
talysis particularly for the application of solar hydrogen production from water. Moreover, Cu
2
O is unstable since it typically
suffers from photocorrosion under irradiation. Thus, we may need to continue this study focusing on these two aspects. On the
one hand, controllable synthesis of Cu
2
O nanocrystals shows that there are still significant challenges to tune the band structure
and morphology for the enhancement of photocatalytic efficiency. On the other hand, based on solid-state electronics, electro-
chemistry/photoelectrochemistry, different modification approaches such as doping, coupled or mixed with other materials,
need further screening and investigation for the improvement of stability under irradiation. In addition, the studies related to
mechanisms of photocatalytic activity of Cu
2
O-based nanocomposites are still insufficient. Fenton-like Cu
+
/Cu
2+
reactions are
proposed and mainly used for interpreting Cu
2
O disinfection in the absence of irradiation. We need to delve into what happens
during Fenton-like Cu
+
/Cu
2+
reactions in photocatalytic organics degradation and H
2
evolution under irradiation. Besides, since
H
2
O
2
proves to be one of the ROS produced both in pristine Cu
2
O and in Cu
2
O/TiO
2
nanocomposites under VL, it is of interest
to discover the synergistic effect in detail for Cu
2
O-based nanocomposites in the presence of Fe
2+
. If so, it is possible to generate
low-cost and high-efficiency in situ Fenton reagents from Cu
2
O-based nanocomposites, which do not require the supply of H
2
O
2
in comparison with traditional Fenton reagents.
aCkNOwledgmeNts
dr. Xiong acknowledges the financial support from the Project of Hubei Provincial department of education (Xd201010406),
the doctor Foundation of Huanggang Normal University (2011cd233), the Project of Industry-Academy-Research Cooperation
of Huanggang Normal University (2012026203), the Project of Hubei Silver dragon Pipes Industry Ltd. (2012013111), and the
National Natural Science Foundation of China (11104101). Prof. Yu thanks support from the National Natural Science
Foundation of China (No. 21377044), Wuhan Planning Project of Science and Technology (No. 2014010101010023) and
self-determined research funds of CCNU from the colleges' basic research and operation of MOe (No. CCNU13F027).
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