Synergic effects of Cu_xO electron transfer co-catalyst and valence band edge control over TiO_2 for efficient visible-light photocatalysis

Bandgap engineering by doping and co‐catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible‐light absorption and charge separation,respectively.Shifting of the TiO2conduction band edge is frequently applied to increase visible‐light absorption but also lowers the reductive properties of photo‐excited electrons.Herein,we report a visible‐light‐driven photocatalyst based on valance band edge control induced by oxygen excess defects and modification with a CuxO electron transfer co‐catalyst.The CuxO grafted oxygen‐rich TiO2microspheres were prepared by ultrasonic spray pyrolysis of the peroxotitanate precursor followed by a wet chemical impregnated treatment.We found that oxygen excess defects in TiO2shifted the valence band maximum upward and improved the visible‐light absorption.The CuxO grafted onto the surface acted as a co‐catalyst that efficiently reduced oxygen molecules to active intermediates(i.e.,O2??radial and H2O2),thus consuming the photo‐generated electrons.Consequently,the CuxO grafted oxygen‐rich TiO2microspheres achieved a photocatalytic activity respectively8.6,13.0and11.0as times high as those of oxygen‐rich TiO2,normal TiO2and CuxO grafted TiO2,for degradation of gaseous acetaldehyde under visible‐light irradiation.Our results suggest that high visible‐light photocatalytic efficiency can be achieved by combining oxygen excess defects to improve visible‐light absorption together with a CuxO electron transfer co‐catalyst.These findings provide a new approach to developing efficient heterojunction photocatalysts.

Preparation and photodetection performance of high crystalline quality and large size β-Ga_(2)O_(3)microwires

Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal quality and large size were grown by the chemical vapor deposition(CVD)method.The microwires reach up to 1 cm in length and were single crystalline with low defect density.Owing to its high crystal quality,a metal–semiconductor–metal photodetector fabricated from a Ga_(2)O_(3)microwire showed a responsivity of 1.2 A/W at 240 nm with an ultrahigh UV/visible rejection ratio(R_(peak)/R_(400 nm))of 5.8×10^(5),indicating that the device has excellent spectral selectivity.In addition,no obvious persistent photoconductivity was observed in the test.The rise and decay time constants of the device were 0.13 and 0.14 s,respectively.This work not only provides a growth method for high-quality Ga_(2)O_(3)microwires,but also demonstrates the excellent performance of Ga_(2)O_(3)microwires in solar-blind ultraviolet detection.

The p-type ZnO thin films obtained by a reversed substitution doping method of thermal oxidation of Zn_3N_2 precursors

P-type ZnO is crucial for the realization of ZnO-based homojunction ultraviolet optoelectronic devices. The problem associated with the preparation of stable p-type ZnO with high hole density still hinders device applications. In this paper,we introduce an alternative route to stabilizing N in the oxidation process, the thermal stability of p-ZnO is significantly improved. Finally, we discuss the limitations of the alternative doping method and provide some prospective outlook of the method.

A tumor-targeting nano-adjuvant for in situ vaccine based on ultrasound therapy

Ultrasound-generated antigens combined with TLR7/8 agonists as adjuvants have demonstrated significant anti-tumor efficacy as an in-situ vaccine.However,the use of TLR7/8 agonists can cause severe inflammatory responses.In this study,we present a novel tumor-targeting nano-adjuvant termed aPDL1-PLG/R848 NPs,which are composed of aPDL1 antibody,Fc-III-4C peptide linker(Fc-linker)and poly(L-glutamic acid)-grafted-R848.Under ultrasound irradiation,antigen-presenting cells activate immune mechanisms in vivo under dual stimulation of in situ antigens and immune adjuvants.The strategy inhibits primary tumor growth and induces a strong antigen-specific immune memory effect to prevent tumor recurrence in vivo.This work offers a safe and potent platform for an in situ cancer vaccine based on ultrasound therapy.

Review on carbon dots:Synthesis and application in biology field

As a multifunctional fluorescent nanomaterial, carbon dots (CDs) not only have small size, stable chemical properties, excellent photoluminescence characteristics, but also exhibit good biocompatibility and low toxicity. It has attracted considerable attention in the field of nanotechnology and biological science. CDs contain abundant functional groups on the surface, which not only retain part of the properties of raw materials, but also may have new photoelectric, catalytic, biomedical, and other functions. In this review, we systematically summarize the synthesis methods, modifications, optical properties, and main biological functions of CDs in recent years. The application of functionalized modified CDs in biological detection, biological imaging, photodynamic therapy, photothermal therapy, targeted therapy, drug delivery, gene delivery, protein delivery, and other biomedical fields is introduced. The latest progress of CDs with its own biomedical function in antioxidant, anti-pathogen, and disease treatment is summarized. Finally, we discuss some problems in the practical application of CDs and look forward to the future development trend of self-functional CDs combined with surface modification to achieve multimodal treatment of diseases.