Multifunctional thin films which can display both photocatalytic and antibacterial activity are of great interest industrially. Here, for the first time, we have used aerosol-assisted chemical vapor deposition to deposit highly photoactive thin films of Cu-doped anatase TiO2 on glass substrates. The films displayed much enhanced photocatalytic activity relative to pure anatase and showed excellent antibacterial (vs Staphylococcus aureus and Escherichia coli) ability. Using a combination of transient absorption spectroscopy, photoluminescence measurements, and hybrid density functional theory calculations, we have gained nanoscopic insights into the improved properties of the Cu-doped TiO2 films. Our analysis has highlighted that the interactions between substitutional and interstitial Cu in the anatase lattice can explain the extended exciton lifetimes observed in the doped samples and the enhanced UV photoactivities observed.

A MXene-GaN-MXene based multiple quantum well photodetector was prepared on patterned sapphire substrate by facile drop casting. The use of MXene electrodes improves the responsivity and reduces dark current, compared with traditional Metal-Semiconductor-Metal (MSM) photodetectors using Cr/Au electrodes. Dark current of the device using MXene-GaN van der Waals junctions is reduced by three orders of magnitude and its noise spectral intensity shows distinct improvement compared with the traditional Cr/Au–GaN–Cr/Au MSM photodetector. The improved device performance is attributed to low-defect MXene-GaN van der Waals interfaces. Thanks to the high quality MXene-GaN interfaces, it is possible to verify that the patterned substrate can locally improve both light extraction and photocurrent collection. The measured responsivity and specific detectivity reach as high as 64.6 A/W and 1.93 × 1012 Jones, respectively, making it a potential candidate for underwater optical detection and communication. The simple fabrication of MXene-GaN-MXene photodetectors spearheaded the way to high performance photodetection by combining the advantages of emerging 2D MXene materials with the conventional III-V materials.

optical properties. However, such materials are either expensive or require vacuum equipment, e.g., metal-organic chemical vapor deposition, to fabricate, [7][8][9] which places a restriction on a wide deployment. In recent years, organometal trihalide perovskites (OTPs) (with a structure of ABX 3 , where A is an organic cation CH 3 NH 3 + (MA), B is Pb 2+ , X is a halide anion or mixed halide) have drawn great attention and been a very promising candidate for opto-electronic applications due to low cost and high throughput solution process. Since the discovery of perovskitebased solar cells (PSCs) by Miyasaka and co-workers [10] power conversion efficiencies have exceeded 22% in less than seven years, [11] thanks to the outstanding physics properties, including the low exciton binding energy, strong light absorption, long carrier lifetime, large carrier diffusion coefficient, and low charge recombination rate. [12][13][14][15][16] These features also make the emerging perovskite materials a promising alternative to conventional semiconductors used in PDs. Indeed, solution-processed OTPs have yielded PDs with excellent device performance. [16][17][18][19][20][21][22][23][24] For instance, both polycrystalline films and single crystals of OTPs have been successfully used to fabricate the narrowband and broadband photodetectors. [25][26][27] As one of the earliest discovered and extensively researched perovskite materials, MAPbI 3 has been regarded as one of the most potential materials for PDs due to its broadband absorption and superb light sensitivity. Dong et al. reported a MAPbI 3 -based photodetector with excellent photoconductive properties. [20] Su et al. reported a self-powered photodetector based on MAPbI 3, which exhibited excellent responsivity and rapid response time for wavelength ranging from ultraviolet to visible light. [28] Chen et al. fabricated a flexible UV-vis-NIR photodetector based on MAPbI 3 with excellent mechanical flexibility and durability. [18] However, some issues about this material still exist. MAPbI 3 tends to degrade and dissociate into MAI and PbI 2 in air. [29][30][31] Recent work on FAPbX 3 (FA: CH 3 (NH 2 ) 2 + , X = I, Br, Cl) PSCs demonstrates better thermal durability than methylammonium perovskites. [31,32] However, FAPbI 3 has two different phases at room temperature: α-phase (desired perovskite phase) and δ-phase (photo-inactive phase). Also, the α-phase perovskite of FAPbI 3 , which is sensitive to solvents and moisture, would turn into the undesired δ-phase in an air atmosphere. [33] Photodetectors, which can convert light signals into electrical signals, are important opto-electronic devices in imaging, optical communication, biomedical/biological sensing, and so on. Here a solution-processed photodetector based on the triple cation perovskite is demonstrated. The perovskite photodetectors show a high detectivity, high speed, as well as excellent environmental stability. Operating at a low voltage bias of 2 V, the photodetectors exhibit a large on/off ratio of 10 5 , ...

Indium gallium nitride (InGaN) is an attractive semiconductor, with a tunable direct bandgap for photoelectrochemical water splitting, but it corrodes in aqueous electrolytes. Cobalt oxide (CoOx) is a promising co-catalyst to protect photoelectrodes and to accelerate the charge transfer. CoOx is earth-abundant and stable in extremely alkaline conditions and shows high activity for the oxygen evolution reaction (OER). In this work, we demonstrate that CoOx directly deposited onto InGaN/GaN multiple quantum wells photoanodes exhibits excellent activity and stability in a strong alkaline electrolyte, 1M NaOH (pH=13.7), for water oxidation up to 28 hours, while a reference sample without the catalyst degraded rapidly in the alkaline electrolyte. Under simulated solar illumination, the CoOx-modified InGaN/GaN quantum well photoanode showed a high photocurrent density of 1.26 mA cm-2 at 1.23 V and an onset potential of-0.03 V versus a reversible hydrogen electrode.