Enhanced Photocatalytic Antibacterial Properties of TiO2 Nanospheres with Rutile/Anatase Heterophase Junctions and the Archival Paper Protection Application

TiO2 has been generally studied for photocatalytic sterilization, but its antibacterial activities are limited. Herein, TiO2 nanospheres with rutile/anatase heterophase junctions are prepared by a wet chemical/annealing method. The large BET surface area and pore size are beneficial for the absorption of bacteria. The rutile/anatase heterojunctions narrow the bandgap, which enhances light absorption. The rutile/anatase heterojunctions also efficiently promote the photogenerated carriers’ separation, finally producing a high yield of radical oxygen species, such as •O2– and •OH, to sterilize bacteria. As a consequence, the obtained TiO2 nanospheres with rutile/anatase heterojunctions present an improved antibacterial performance against E. coli (98%) within 3 h of simulated solar light irradiation, exceeding that of TiO2 nanospheres without annealing (amorphous) and TiO2 nanospheres annealing at 350 and 550 °C (pure anatase). Furthermore, we design a photocatalytic antibacterial spray to protect the file paper. Our study reveals that the TiO2 nanospheres with rutile/anatase heterojunctions are a potential candidate for maintaining the durability of paper in the process of archival protection.

Modified surface states of NaGdF4:Yb3+/Tm3+ up-conversion nanoparticles via a post-chemical annealing process

An amorphous layer acting as a quenching center at the surface of oleic acid-capped NaGdF4:Yb3+/Tm3+ nanoparticles is observed directly, which can be reconstructed via a novel post-chemical annealing process.

Properties of A-(Si,Ge) Materials and Devices grown using Chemical Annealing

ABSTRACTChemical annealing is a powerful technique for controlling H bonding and optical absorption in amorphous semiconductors. We have shown previously that the use of careful chemical annealing by Argon can lower the bandgap of a-Si:H while maintaining electronic properties in both films and devices. In this work, we describe new work on chemical annealing of A-(Si,Ge):H films and devices. The technique consists in growing very thin layers (1-3 nm) of A-(Si,Ge) from mixtures of hydrogen, Silane and Germane, and then subjecting this thin layer to ion bombardment by Ar. The cycle is repeated many times to achieve the desired thickness of the intrinsic layer. The resulting film and device were measured for their composition using energy dispersive spectroscopy (EDS) analysis. We discovered that the composition itself, namely the Ge:Si ratio in the film, could be varied by changing the ion bombardment conditions. Lower energy bombardment led to a higher Ge:Si ratio for the same germane/Silane ratio in the gas phase. By controlling ion bombardment during the Ar annealing cycle, we were able to reduce the H content of the film and achieve good electronic properties. It will be shown that by appropriate control over ion energies, one can obtain films and devices which are of good quality and low bandgap as well.