Carbon nanotubes (CNTs) have attracted much interest because of their special physicochemical properties. Herein, O2 plasma-treated CNTs (denoted as PS-CNTs) are incorporated within a TiO2 matrix (denoted as PS-CNTs/TiO2) as photoanodes in dye-sensitized solar cells (DSSCs). The PS-CNTs/TiO2 composites provide more uniform holes and rough surface over the photoanode and also provide a greater degree of dye adsorption and lower levels of charge recombination, as compared to either chemical modified CNTs/TiO2 (denoted as CM-CNTs/TiO2) or TiO2 alone. The high dispersion of TiO2 on PS-CNTs can improve the electron conduction paths, leads to high electron transfer efficiency, and thereby results in the high performance of the DSSC devices. Herein, the PS-CNTs/TiO2-based working photoanode demonstrates a conversion efficiency of 6.34% in DSSCs, which is ∼75% higher than that of conventional TiO2-based devices.

Three‐dimensional SnO2/α‐Fe2O3 semiconductor hierarchical nanoheterostructures were synthesized for photocatalysis through a low‐cost and environmentally friendly hydrothermal strategy, by crystallographic‐oriented epitaxial growth of SnO2 on three‐dimensional α‐Fe2O3 flowerlike hierarchical nanostructures. In this photocatalyst, visible‐light‐active Fe2O3 flowerlike hierarchical nanostructures were used as a medium to absorb photons and convert them into photogenerated charges, and SnO2 nanoparticles were used as charge collectors to transport the photogenerated charges. The SnO2/α‐Fe2O3 semiconductor hierarchical nanoheterostructures exhibited excellent visible‐light photocatalytic ability for the degradation of methylene blue; this was attributed to the large specific surface area, wide visible‐light absorption range, and efficient electron–hole pair separation properties of the SnO2/α‐Fe2O3 nanoheterostructures. The SnO2/α‐Fe2O3 material showed improved separation of photogenerated electron–hole pairs owing to the potential‐energy differences between SnO2 and α‐Fe2O3, and therefore exhibited enhanced photocatalytic activity. This paper highlights the SnO2/α‐Fe2O3 semiconductor hierarchical nanoheterostructures as potentially more environmentally friendly materials for use in organic pollutant degradation for environmental pollution cleanup operations.

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