In this study, we report a feasible method to synthesize a ternary nanocomposite, molybdenum disulfide/polyaniline/reduced graphene oxide aerogel (MoS2/PANI/rGO), via a two-step approach. Molybdenum disulfide/polyaniline (MoS2/PANI) is prepared by in situ polymerization. Graphene oxide is well-dispersed by loading MoS2/PANI nanoparticles (50–80 nm in size) and reduced using urea via a hydrothermal treatment, achieving the ternary nanocomposite. As for the composites prepared at different mass ratios of MoS2/PANI to rGO, the ternary MoS2/PANI/rGO with a mass ratio of 1:1 has a high specific capacitance of 618 F g−1 at 1.0 A g−1 and 476 F g−1 at 20 A g−1 with a retainment of 96% in a three-electrode system, in comparison to the specific capacitance of 418 F g−1 at 1.0 A g−1 and 78% retained capacitance after 2000 cycles of MoS2/PANI electrode. The combined effects between the three components in the ternary composite aerogels taking advantage of both charging and faradaic processes can readily explain the excellent electrochemical performance.

The manipulation of charge transfer at CuPc/graphene interface has been demonstrated by treating pristine graphene with O2 plasma. As revealed by in situ ultraviolet photoelectron spectroscopy measurements, a much stronger interfacial charge transfer occurs when the pristine graphene is exposed to O2 plasma prior to the growth of CuPc films, which is attributed to the increased work function of graphene after O2 plasma treatment. Moreover, the highest occupied molecular orbital leading edge of CuPc locates at ∼0.80 eV below substrate Fermi level on O2 plasma treated graphene, whereas it locates at ∼1.10 eV on pristine graphene. Our findings provide detailed information regarding the electronic structure at CuPc/graphene and CuPc/O2 plasma treated graphene interfaces. The increased work function in combination with the relatively smaller energy offset between the highest occupied molecular orbital of CuPc and Fermi level of O2 plasma treated graphene facilitates the extraction of holes at the interface, and hence paves the way for improving the performance of graphene-based organic photovoltaic cells.

It is commonly considered that the morphology and interface of semiconductor–reduced graphene oxide (rGO) composite photocatalysts play a crucial role in determining their photocatalyzing performance. Herein, we report on the design and synthesis of BiVO4–rGO nanocomposites with efficient interfacial contact by self-assembly of positively charged amorphous BiVO4 powders with negatively charged graphene oxide (GO), followed by a one-step GO reduction and BiVO4 crystallization via hydrothermal treatment. The as-prepared BiVO4–rGO nanocomposites exhibit high visible light photocatalytic efficiency for the degradation of model dyes, and are significantly superior to bare crystalline BiVO4 and BiVO4–rGO–U that is hydrothermally synthesized using the mixture of GO nanosheets and BiVO4 powders without modification of surface charge. Using multiple characterization techniques, we found that the enhanced photocatalytic performance of BiVO4–rGO arises from the synergistic effects between the microscopic crystal structure of BiVO4 with smaller particle size and more sufficient interfacial interaction between BiVO4 and graphene sheets, leading to increased photocatalytic reaction sites, extended photoresponding range, enhanced photogenerated charge separation, and transportation efficiency. This work may provide a rational and convenient strategy to construct highly efficient semiconductor–rGO nanocomposite photocatalysts with well-contacted interface toward environmental purification and solar energy conversion.Keywords: interfacial interaction; photocatalysis; rGO; self-assembly; surface charge modification

The valence band offsets (ΔEV) of Zn1−xMgxO/ZnO heterojunctions grown by plasma-assisted molecular beam epitaxy were measured by photoelectron spectroscopy. From the directly obtained ΔEV values, the related conduction band offsets (ΔEC) were deduced. All the Zn1−xMgxO/ZnO heterojunctions exhibit a type-I band alignment with the ΔEC/ΔEV estimated to be 1.5, 1.8, 2.0 for x = 0.10, 0.15 and 0.20, respectively. The band offsets of Zn1−xMgxO/ZnO heterojunctions depend on Mg composition. The accurate determination of energy band alignment of Zn1−xMgxO/ZnO is helpful for designing ZnO based optoelectronic devices.

•Mn–Li codoping facilitates the non-polar/semi-polar growth of ZnO on quartz.•The control of preferred orientation is tuned by adjusting PO2 and Ts.•Non c-axis oriented ZnO film is obtained on quartz substrate.Non c-axis oriented ZnO thin films were grown on quartz substrates via pulsed laser deposition (PLD) through Mn–Li co-doping. Both oxygen pressure (PO2) and growth temperature (Ts) are revealed to have significant effects on the structural properties of the Zn(Mn, Li)O (ZMLO) films. The self-textured film with predominant (101¯1) preferred orientation (PO) is achieved. In addition, using the ZMLO as a buffer layer, the growth of undoped pure ZnO with successive orientation characteristic is realized as well. Emission study was performed for the ZnO layer showing strong near-band-edge emission with minor deep level emission, indicating high optical quality of the ZnO thin film.

Fe-doped and Fe–Ga co-doped ZnO diluted magnetic semiconductor thin films on quartz substrate were studied. Rapid annealing enhanced the ferromagnetism (FM) of the films grown in Ar/O2. All the films grown in Ar are n-type and the carrier concentration could increase significantly when Ga is doped. The state of Fe in the films was investigated exhibiting Fe3+. Magnetic measurements revealed that room temperature ferromagnetism in the films were doping concentration dependent and would enhance slightly with Ga doping. The origin of the observed FM is interpreted by the overlapping of polarons mediated through oxygen vacancy based on the bound magnetic polaron model.

•The homobuffer thickness effect on the conduction type of undoped ZnO is discussed.•Thicker homobuffer layer leads to weak p-type conductivity.•Low temperature PL and TEM are employed to investigate origin of p-type behavior.•A correlation between 3.32-eV emission and undoped p-type non-polar ZnO is revealed.Non-polar (101¯0) ZnO thin films were epitaxially grown on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The homobuffer thickness effect on the conduction type of undoped ZnO thin films is carefully investigated. With a relatively thicker buffer layer, weak p-type conductivity with a hole concentration of 1.6×1016 cm−3, a Hall mobility of 0.33 cm2 V−1 s−1, and a resistivity of 1.2×103 Ω cm are achieved for the film. By careful analysis of results from low temperature photoluminescence and transmission electron microscopy measurements, a correlation of the 3.32-eV emission to the p-type conductivity in the undoped non-polar ZnO films is revealed and discussed. The results are important to help deepen understanding of the origin of p-type behavior in ZnO-based materials.

•The Na-doped non-polar m-plane ZnO films were grown on m-plane sapphire using MBE.•Uniform m-plane orientation ZnO grown on m-plane sapphire benefits from Na-doping.•Na content plays a key role in determining the conduction of the ZnO films.We report on the growth and characterization of Na-doped non-polar ZnO thin films, which have been prepared on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The effects of Na contents on structural, morphological, electrical, and optical properties of Na-doped non-polar m-plane ZnO films are investigated. All the doped thin films have uniform m-plane orientation, which benefit from Na-doping. Na content plays a key role in determining the conduction of the ZnO films. An optimized result with a hole concentration of 5.3×1016 cm−3, a Hall mobility of 0.22 cm2 V−1 s−1, and a resistivity of 530 Ω cm is achieved at beam equivalent pressure of the elemental Na source of 8.7×10−9 Torr, and the films are electrically stable over several months.

The valence band offsets (ΔEV) of Zn1−xMgxO/ZnO heterojunctions grown by plasma-assisted molecular beam epitaxy were measured by photoelectron spectroscopy. From the directly obtained ΔEV values, the related conduction band offsets (ΔEC) were deduced. All the Zn1−xMgxO/ZnO heterojunctions exhibit a type-I band alignment with the ΔEC/ΔEV estimated to be 1.5, 1.8, 2.0 for x = 0.10, 0.15 and 0.20, respectively. The band offsets of Zn1−xMgxO/ZnO heterojunctions depend on Mg composition. The accurate determination of energy band alignment of Zn1−xMgxO/ZnO is helpful for designing ZnO based optoelectronic devices.