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Although TiO2 was formerly a common material for photocatalysis reactions, its wide band gap (3.2 eV) results in absorbing only ultraviolet light, which accounts for merely 4% of total sunlight. Modifying TiO2 has become a focus of photocatalysis reaction research, and combining two metal oxide semiconductors is the most common method in the photocatalytic enhancement process. When MoO3 and TiO2 come into contact to form a heterogeneous interface, the photogenerated holes excited from the valence band of MoO3 should be transferred to the valence band of TiO2 to effectively reduce the charge recombination of photogenerated electron–hole pairs. This can efficiently separate the pairs and promote photocatalysis efficiency. In addition, photocurrent enhancement is attributed to the strong near-field and light-scattering effects from plasmonic Ag nanoparticles. In this work, we fabricated MoO3-coated TiO2 nanotube heterostructures with a 3D hierarchical configuration through two-step anodic oxidation and a facile hydrothermal method. This 3D hierarchical structure consists of a TiO2 nanotube core and a MoO3 shell (referred to as TNTs@MoO3), as characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy. Electronic supplementary material The online version of this article (10.1186/s11671-017-2327-y) contains supplementary material, which is available to authorized users.

In this study, a 4 in. CMK-8-Nafion membrane was fabricated using three-dimensional cubic ordered mesoporous carbon CMK-8 blended with a Nafion polymer. Plasmon-resonance hot electrons and holes from Au nanoparticles (NPs) combined with this CMK-8-Nafion membrane resulted in the effective decomposition of methyl orange (MO) due to the synergetic work of hot carriers with mesoporous carbon; a sample of Au/CMK-8-Nafion exposed to outdoor sunlight radiation for 150 min successfully removed 97% of MO. Fourier transform infrared spectroscopy (FTIR) was employed to examine the generation of hydroxyl groups (OH-) during decomposition. Finally, the spatial distribution of hydroxyl groups was also investigated across the different coverage densities of plasmonic Au NPs.

High specific surface area bipyramidal and pseudocubic polyhedral α-Fe 2 O 3 nanocrystals were fabricated for hydrogen reduction in a water-splitting process. Two different facets of polyhedral α-Fe 2 O 3 nanocrystals were synthesized via a versatile hydrothermal route. Typically, photocatalytic activity of hematite is limited by its relatively poor absorptivity, very short excited-state lifetime, and short hole diffusion length. To address these issues, a pseudocubic polyhedral α-Fe 2 O 3 photoelectrode was fabricated that achieved a spontaneous charge spatial separation during the water-splitting process. Additionally, Sn from the FTO substrate was diffused and doped into polyhedral α-Fe 2 O 3 during the sintering process to serve as an electron donor and increase the carrier density. To further exploit the surface plasmon resonance (SPR) properties and enhance the water-splitting efficiency of polyhedral α-Fe 2 O 3 photoelectrodes, Au nanoparticles were decorated on the surface of Fe 2 O 3 . This increased incident light absorption and suppressed charge recombination by the strong field generated from collective oscillations of surface electrons in the Au nanoparticles. Subsequently, this Au/pseudocubic Fe 2 O 3 photoelectrode demonstrated a 9.05 μmol/min hydrogen production rate.

“Carbon-based material” has demonstrated a great potential on water purification due to its strong physical adsorption to organic pollutants in the water. Three-dimensional cubic ordered mesoporous carbon (CMK-8), one of the well-known ordered mesoporous carbons, was prepared by using nanocasting method with mesoporous silica (KIT-6) as the template. In this study, CMK-8 blended with Nafion polymer to form a free-standing mesoporous CMK-8-Nafion composite membrane. The synthesis of high crystallinity CMK-8 was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). More than 80% methyl orange (MO) removal efficiency was observed under 254-nm UV irradiation after 120 min. Ninety-two percent recycling performance was remained after four recycling tests, which indicated a reliable servicing lifetime for the water purification. Furthermore, an additional layer of plasmonic silver nanoparticles (Ag NPs) was integrated into this CMK-8-Nafion membrane for higher pollutant removal efficiency, attributing from the generation of plasmon-resonance hot electrons from Ag NPs. A 4-in. CMK-8-Nafion composite membrane was also fabricated for the demonstration of potential large-scale utilization.

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