N‑Doped TiO₂ Coupled with Manganese-Substituted Phosphomolybdic Acid Composites As Efficient Photocatalysis-Fenton Catalysts for the Degradation of Rhodamine B

The effectiveness of photocatalytic and Fenton reactions in the synergistic treatment of water pollution problems has become indisputable. In this paper, nitrogen-doped TiO2 was selected as the catalyst for the photocatalytic reaction and manganese-substituted phosphomolybdic acid was used as the Fenton reagent, the two of which were combined together by acid impregnation to construct a binary photocatalysis-Fenton composite catalyst. The degradation experiments of the composite catalyst on RhB indicated that under UV–vis irradiation, the composite catalyst could degrade RhB almost completely within 8 min, and the degradation rate was 19.7 times higher than that of N-TiO2, exhibiting a superior degradation ability. Simultaneously, a series of characterization methods were employed to analyze the structure, morphology, and optical properties of the catalysts. The results demonstrated that the nitrogen doping not only expanded the photo response range of TiO2 but reduced the work function of TiO2, which facilitated the transfer of electrons to the loaded Mn-HPMo side and further promoted the electron–hole separation efficiency. In addition, the introduction of Mn-HPMo provided three pathways for the activation of hydrogen peroxide, which enhanced the degradation activity. This study provides novel insights into the construction of binary and efficient catalysts with multiple hydroxyl radical generation pathways

High-Performance Photoelectronic Sensor Using Mesostructured ZnO Nanowires

Semiconductor photoelectrodes that simultaneously possess rapid charge transport and high surface area are highly desirable for efficient charge generation and collection in photoelectrochemical devices. Herein, we report mesostructured ZnO nanowires (NWs) that not only demonstrate a surface area as high as 50.7 m²/g, comparable to that of conventional nanoparticles (NPs), but also exhibit a 100 times faster electron transport rate than that in NP films. Moreover, using the comparison between NWs and NPs as an exploratory platform, we show that the synergistic effect between rapid charge transport and high surface area leads to a high performance photoelectronic formaldehyde sensor that exhibits a detection limit of as low as 5 ppb and a response of 1223% (at 10 ppm), which are, respectively, over 100 times lower and 20 times higher than those of conventional NPs-based device. Our work establishes a foundational pathway toward a better photoelectronic system by materials design

Photoelectrochemical and Photovoltaic Properties of p–n Cu₂O Homojunction Films and Their Photocatalytic Performance

The improvement of photoinduced charge separation is the key for light-harvesting systems in both photovoltaic and photoelectrochemical solar cells. In this study, the charge separation efficiency has been modulated through varying the magnitude of interfacial electric field in p–n Cu₂O homojunction films prepared by simple electrodeposition method. The photoelectrochemical and surface photovoltage measurements were used to investigate the behaviors of photoinducded charge carriers in different p–n Cu₂O homojunction films. The results confirmed that the p–n Cu₂O homojunction film which exhibited the highest charge separation efficiency resulted in the highest activity in photocatalytic reduction of methyl viologen. These implied that it is possible to achieve high charge separation efficiency via constructing a large magnitude of interfacial electric field within a semiconductor using a simple electrodeposition method

Improved Electron Transfer between TiO₂ and FTO Interface by N‑Doped Anatase TiO₂ Nanowires and Its Applications in Quantum Dot-Sensitized Solar Cells

The growth of anatase TiO₂ nanowires (NWs) on fluorine doped tin oxide (FTO) substrates through hydrothermal reaction has attracted wide attention and research, especially in the case of the solar cells. Actually, the built-in electric field at the anatase TiO₂ NWs/FTO interface leads to the photoexcited holes transfer to FTO conductive substrates because the Fermi energy of anatase TiO₂ NWs film is higher than that of FTO substrates. Yet efficient transport of photoexcited electron to the FTO conductive substrates is desirable. Hence, the built-in electric field at the pure TiO₂ NWs/FTO interface has prevented anatase TiO₂ NWs-based solar cells from achieving a higher photoelectric performance. In this work, we elaborately design and construct the N-doped anatase TiO₂ NWs/FTO interface with the desirable orientations from FTO toward N-doped anatase TiO₂ NWs, which favors the photoexcited electron transfer to the FTO conductive substrates. The surface photovoltage (SPV) and Kelvin probe measurements demostrate that the N-doped anatase TiO₂ NWs/FTO interface favors the photoexcited electron transfer to the FTO conductive substrates due to the fact that the orientation of the built-in electric field at the N-doped TiO₂ NWs/FTO interface is from FTO toward TiO₂. The photoexcited charge transfer dynamics of CdS QD-sensitized TiO₂ NWs and N-doped TiO₂ NWs electrodes was investigated using the transient photovoltage (TPV) and transient photocurrent (TPC) technique. Benefiting from the desirable interface electric field, CdS-based quantum dot-sensitized solar cells (QDSCs) with the optimal N doping amount exhibit a remarkable solar energy conversion efficiency of 2.75% under 1 sun illumination, which is 1.46 times enhancement as compared to the undoped reference solar cells. The results reveal that the N-doped anatase TiO₂ NWs electrodes have promising applications in solar cells

Effect of Photogenerated Charge Transfer on the Photocatalysis in High-Performance Hybrid Pt–Co:ZnO Nanostructure Photocatalyst

Hybrid Pt–Co:ZnO nanostructure photocatalysts were prepared via a facile two-step synthetic strategy. SPS and TPV investigations demonstrate the existence of the synergetic effect between Pt and Co dopants. Such synergetic effect could make use of visible photons as well as facilitates the separation of photogenerated charges to prevent recombination, effectively prolongating the charges lifetime to participate photocatalytic reaction. The synergetic effect exist in Pt–Co:ZnO inducing as high as 7.7-fold in photovoltaic response and 10-fold in the photo–activity for hybrids compared to Co:ZnO

Facile Fabrication of Hierarchical TiO₂ Nanobelt/ZnO Nanorod Heterogeneous Nanostructure: An Efficient Photoanode for Water Splitting

The TiO₂ nanobelt/ZnO nanorod composite photoelectrodes with flower-like and/or grass-like microstructures have been fabricated via a facile solution growth routine, just by controlling the treatment of the TiO₂ nanobelt substrate. For the flower-like composite, the ZnO nanorods disperse orientationally on TiO₂ nanobelt films, while for the grass-like one, ZnO nanorods grow disorderly like grass on the TiO₂ nanobelt film surface. Furthermore, quasi-Fermi energy level changes of both photoelectrodes have been quantitatively characterized by the surface photovoltage based on the Kelvin probe, which clearly reveals the efficiency of photogenerated electron–hole separation. Owing to the decrease of quasi-Fermi energy level, the flower-like TiO₂ nanobelt/ZnO nanorod heterogeneous nanostructure presents a high efficiency of photogenerated electron–hole separation. Therefore, the flower-like TiO₂ nanobelt/ZnO nanorod heterogeneous nanostructure photoelectrode has achieved a better performance of water splitting compared with the grass-like TiO₂ nanobelt/ZnO nanorod one

pH-Dependent Assembly of Tungsten Oxide Three-Dimensional Architectures and Their Application in Photocatalysis

In this work, tungsten oxide (WO₃) with three-dimensional flower-like and wheel-like architectures, based on the spontaneous aggregation of one-dimensional nanorods, were successfully fabricated by adjusting the pH of the precursor solution. The influence of pH on the morphologies of WO₃ was systematically studied, and the different WO₃ architectures were used to photocatalytically degrade rhodamine B. The kinetic features of photoinduced charges of as-prepared WO₃ have been investigated by surface photovoltage spectroscopy and transient photovoltage techniques in detail. WO₃ with wheel-like and flower-like structures possess the higher charge separation efficiency and the lower recombination rate of photoinduced charges, resulting in higher photocatalytic activity for the degradation of RhB

Bismuth Oxybromide with Reasonable Photocatalytic Reduction Activity under Visible Light

The original bismuth-based oxyhalide, known as the Sillén family, is an important photocatalyst due to its high photocatalytic oxidation activity. Here, we report a bismuth-based photocatalyst, Bi₂₄O₃₁Br₁₀, with reasonable reduction activity. The photoreduction capability of Bi₂₄O₃₁Br₁₀ in H₂ evolution from water reduction is 133.9 μmol after 40 h under visible light irradiation. Bi₂₄O₃₁Br₁₀ presents the highest activity among Bi₂O₃, BiOBr, and Bi₂₄O₃₁Br₁₀ in photocatalytic reduction of the Cr (VI) test, and Cr (VI) ions are totally removed in 40 min. The Mott–Schottky test shows the bottom of the conduction band fits the electric potential requirements for splitting water to H₂. First-principles calculations indicate the conduction band of Bi₂₄O₃₁Br₁₀ mainly consists of hybridized Bi 6p and Br 4s orbitals, which may contribute to the uplifting of the conduction band