Properties of Halide Perovskite Photodetectors with Little Rubidium Incorporation

This study investigates the effects of Rb doping on the Rb-formamidinium-methylammonium-PbI3 based perovskite photodetectors. Rb was incorporated in the perovskite films with different contents, and the corresponding photo-response properties were studied. Doping of few Rb (~2.5%) was found to greatly increase the grain size and the absorbance of the perovskite. However, when the Rb content was greater than 2.5%, clustering of the Rb-rich phases emerged, the band gap decreased, and additional absorption band edge was found. The excess Rb-rich phases were the main cause that degraded the performance of the photodetectors. By space charge limit current analyses, the Rb was found to passivate the defects in the perovskite, lowering the leakage current and reducing the trap densities of carriers. This fact was used to explain the increase in the detectivity. To clarify the effect of Rb, the photovoltaic properties were measured. Similarly, h perovskite with 2.5% Rb doping increased the short-circuit current, revealing the decline of the internal defects. The 2.5% Rb doped photodetector showed the best performance with responsivity of 0.28 AW−1 and ~50% quantum efficiency. Detectivity as high as 4.6 × 1011 Jones was obtained, owing to the improved crystallinity and reduced defects.

Enhanced Patterned Cocatalyst TiO2/Fe2O3 Photoanodes for Water-Splitting

In this study, we used a hot-pressing process to enhance the photocatalytic properties of TiO2/Fe2O3 bimetallic oxide with a periodic patterned structure on the surface to increase photon absorption for photocatalysis in the oxygen evolution reaction for water splitting. The hot-pressed samples show that combining the two metal oxides improves the absorption band edge of the electrode at different wavelengths. The patterned structure obtained using the hot-pressing process successfully improves photon absorption, resulting in a two-fold enhancement compared with a flat surface electrode.

Enhanced Patterned Cocatalyst TiO2/Fe2O3 Photoanodes for Water-Splitting

In this study, we used a hot-pressing process to enhance the photocatalytic properties of TiO2/Fe2O3 bimetallic oxide with a periodic patterned structure on the surface to increase photon absorption for photocatalysis in the oxygen evolution reaction (OER) for water splitting. The hot-pressed samples show that combining the two metal oxides improves the absorption band edge of the electrode at different wavelengths. The patterned structure obtained using the hot-pressing process successfully improves photon absorption, resulting in a two-fold enhancement compared with a flat surface electrode.

Preparation and photocatalytic hydrogen evolution of g-C3N4/ZnO composite

The photocatalytic composite of g-C3N4/ZnO with different g-C3N4 content have been prepared by thermopolymerization method. The catalysts are characterized and analyzed by SEM, XRD, UV-Vis, BET and other analytical methods. The results show that g-C3N4/ZnO composites caused the red shift of the absorption band edge of ZnO, which increased the absorption of visible light and the separation rate of photogenerated electron-hole pairs. It is found that the H2 production rate of 25% g-C3N4/ZnO sample is best with 306.25 μmol∙h-1∙g-1, which is 4.6 times higher than of g-C3N4.

Fingerprinting of Nitroaromatic Explosives Realized by Aphen-functionalized Titanium Dioxide

Developing sensing materials for military explosives and improvised explosive precursors is of great significance to maintaining homeland security. 5-Nitro-1,10-phenanthroline (Aphen)-modified TiO2 nanospheres are prepared though coordination interactions, which broaden the absorption band edge of TiO2 and shift it to the visible region. A sensor array based on an individual TiO2/Aphen sensor is constructed by regulating the excitation wavelength (365 nm, 450 nm, 550 nm). TiO2/Aphen shows significant response to nitroaromatic explosives since the Aphen capped on the surface of TiO2 can chemically recognize and absorb nitroaromatic explosives by the formation of the corresponding Meisenheimer complex. The photocatalytic mechanism is proved to be the primary sensing mechanism after anchoring nitroaromatic explosives to TiO2. The fingerprint patterns obtained by combining kinetics and thermodynamics validated that the single TiO2/Aphen sensor can identify at least six nitroaromatic explosives and improvised explosives within 8 s and the biggest response reaches 80%. Furthermore, the TiO2/Aphen may allow the contactless detection of various explosives, which is of great significance to maintaining homeland security.

Comparative study of absorption band edge tailoring by cationic and anionic doping in TiO2

Titanium dioxide (TiO2) is one of the most favored metal oxide semiconductors for the use as photoanode in photoelectrochemical cells (PEC) splitting the water into hydrogen and oxygen. However, the major impediment is its large bandgap that limits its utilization as photoanode. Doping has evolved as an effective strategy for tailoring optical and electronic properties of TiO2. This paper describes the synthesis of undoped as well as iron (Fe, cationic) and nitrogen (N, anionic) doped nanocrystalline titanium dioxide by sol-gel spin coating method for solar energy absorption in the visible region. All the prepared thin films were characterized by X-ray diffraction and UV-Vis spectroscopy. Doping of both Fe and N into TiO2 resulted in a shift of absorption band edge towards the visible region of solar spectrum.