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Coating of photocatalytic nanomaterials on various surfaces enables interesting applications. This work demonstrates the ability of the aerosol-assisted chemical vapor deposition (AACVD) approach to prepare high-quality BiOCl nanostructure-based films and also to tune the nanostructure and photocatalytic properties of the films by varying the solvent and carrier gas. Solvents have a dramatic impact on the surface morphologies and crystallite size. X-ray diffraction (XRD) and grazing incidence X-ray diffraction (GIXRD) analyses indicate that BiOCl crystals displayed preferential growth in the (101) plane in most samples, while both the (101) and (102) planes were favored in films deposited using ethyl acetate and methanol. Surface energy and adsorption energy calculation reveal that the preferred growth depends on the interaction between the Bi atom and solvent molecules. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) characterizations showed that all films did not contain any impurity elements but did contain some oxygen vacancies. The obtained nanostructured BiOCl films show good photocatalytic properties. The highest photocatalytic NOx removal efficiency is achieved in the film prepared using ethyl acetate and air, which we attribute to the large crystallite size and therefore high mobility of the carriers. Herein, we show that different crystal morphologies and sizes of BiOCl have strong impacts on the photocatalytic activity toward NO oxidation, and both factors can be effectively tuned in the AACVD process. Such knowledge may be useful for future research on coating materials for resolving environmental problems. [ABSTRACT FROM AUTHOR]

In this work, we study and compare the photo-induced conductivity of a two-dimensional electron gas (2DEG) at the bare surface of SrTiO3 (STO) and in the heterostructure of BiFeO3 (BFO) and STO, where BFO was deposited by radio frequency magnetron sputtering. The photo-induced conductance of the BFO/STO interface shows a large increase which is 20.62 times more than the sum of photo-induced conductance from each individual BFO thin film and STO crystal. Since this photo-induced conductance of the BFO/STO heterostructure can be adjusted to become higher and lower by applying an electric field to the top surface, we attribute this large increase to the strong photo-induced electrical polarization of BFO. With the two-point setup of positive bias and negative bias, the conductivity also exhibits diode-like behavior where the forward and backward resistances are different. This work provides methods to interplay between light irradiation, electric field, and conductivity in all-oxide electronics. [ABSTRACT FROM AUTHOR]

The influence of ultraviolet (UV)-induced oxygen vacancies on dynamic changes of electrical conductance in a random-oriented SrTiO3 polycrystalline and SrTiO3 single crystals with (100), (110), and (111) surfaces is reported in this study. It was discovered that a large fraction of ultraviolet-induced oxygen vacancies in the SrTiO3 polycrystalline are primarily contributed from grain boundaries, but these oxygen vacancies are less influenced to the reversible conductance changes due to UV irradiation. The dynamic change of electrical conductance in the polycrystalline is similar to what has been observed for the polar (110) and (111) oriented single crystals, offering a potential alternative for multifunctional electronic devices. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal carbides, carbonitrides, and nitrides, called MXenes, exhibit high metallic conductivity, ion intercalation capability, and reversible redox activity, prompting their applications in energy storage and conversion, electromagnetic interference (EMI) shielding, and electronics, among many other fields. It has been shown that replacement of ∼50% of carbon atoms in the most popular MXene family member, titanium carbide (Ti3C2Tx), by nitrogen atoms, forming titanium carbonitride (Ti3CNTx), leads to drastically different properties. Such properties include very high negative charge in solution and extreme EMI shielding effectiveness, exceeding all known materials, even metals at comparable thicknesses. Here, by using ultraviolet photoemission spectroscopy (UPS), the electronic structures of Ti3CNTx and Ti3C2Tx are systematically investigated and compared as a function of charge carrier density. We observe that, in contrast to Ti3C2Tx, the Ti 3p core-level of Ti3CNTx exhibits a counterintuitive shift to a lower binding energy of up to ∼250 meV upon increasing the electron density, which is a spectroscopic signature of negative electronic compressibility (NEC). These experimentally measured chemical potential shifts are well captured by the density functional theory (DFT) calculation. The DFT results also further suggest that the hybridization of titanium–nitrogen bonding in Ti3CNTx helps to promote the available states of Ti atoms for receiving more electrons above the fermi level and leads to the observed NEC. Our findings explain the differences in electronic properties between the two very important and widely studied MXenes and also suggest a new strategy to apply the NEC effect of Ti3CNTx in energy and charge storage applications. [ABSTRACT FROM AUTHOR]

Due to 2nd-order Jahn-Teller effect, some M cations such as Ti4+, Sn4+, In3+, Nb5+, Cu2+ and W6+ are allowed to enter the MO 6 octahedral site while maintaining the high-symmetry structure of MTe 3 O 8. Therefore, the series of MTe 3 O 8 compounds when M = Sn, Ti, In 0·5 Nb 0·45 V 0.05 and In 0·4 Cu 0·1 Nb 0·4 W 0.1 were successfully synthesized. Rietveld refinement is utilized to visualize the crystal structures. M − O bonds are expanded because of the larger M cations while the O-M-O angles are distorted slightly. As a result of stereoactive 5 s 2 lone-pair electron of Te4+ in TeO 4 E unit, the structure is flexible as reflected by the small variation of Te–O bond lengths and O–Te–O angles. XANES reveal that the local structures of all compounds are preserved. However, different M cations affect their color and electronic band structures, which can be explained differently by the simple band-to-band transition, the VB-V 3 d electronic transition and the d-d electronic transition. [Display omitted] • In 0·5 Nb 0·45 V 0·05 Te 3 O 8 and In 0·4 Cu 0·1 Nb 0·4 W 0·1 Te 3 O 8 were first studied. • Both short-range and long-range orderings are preserved in all compounds. • XANES and XPS spectra are investigated in detail. • The effects of M cations on electronic structures and optical properties are discussed. [ABSTRACT FROM AUTHOR]