Delamination treatment is crucial in promoting the activity of bulk graphitic carbon nitride (g-CN). However, most of the currently used methods of exfoliating bulk g-CN to achieve g-CN thin layers suffer from low yield and environmental pollution. Herein, we developed a facile bacterial etching approach for the preparation of high-quality g-CN nanosheets by exfoliating bulk g-CN under room temperature. Morphology and physicochemical characterizations show that the bacteria-treated g-CN (BT-CN) samples, especially BT-CN-2d, have a lamina-like two-dimensional (2D) in-plane porous structure, a significantly enlarged specific surface area (82.61 m g), and a remarkable narrow band gap (2.11 eV). X-ray photoelectron spectroscopy and electron paramagnetic resonance spectra confirm the dramatic enrichment of unpaired electron in the BT-CN-2d g-CN nanosheets. EIS spectra and photocurrent tests indicate the fast electron transportation. As a result, the representative BT-CN-2d g-CN photocatalyst shows an optimal visible light-driven photocatalytic performance in water disinfection (fourfold higher than bulk g-CN), as well as good cycle stability. This moderate and clean bacterial etching process can be realized in tens of gram scale in the laboratory and should be readily extended to kilogram scale. The present work provides fundamental knowledge about the scalable production of high-quality g-CN by bioengineering method, offering extendable availability for designing and fabricating other functional 2D materials.

TiO2 and graphitic carbon (GC) composites with hierarchical pore structures were synthesized using Staphylococcus aureus (ATCC6538) as the biotemplate to modify Degussa P25 TiO2 powder. Then, the composites were applied as photocatalysts for Cr6+ reduction under visible light irradiation. X-ray diffraction, Raman spectroscopy, transmission electron microscopy, nitrogen adsorption–desorption analysis, and X-ray photoelectron spectroscopy demonstrated the presence of a GC coating layer and a unique anatase/rutile mixed crystal phase of TiO2 even after heating at 800 °C. The novel TiO2@GC composites, especially the S-P25-800 sample, which possessed abundant hierarchical mesoporous structures, exhibited strong catalytic activities in Cr6+ photoreduction under visible light. This work provides light to overcome the challenge on synthesis of GC modified TiO2 photocatalysts with the highly reactive but heat-labile anatase main crystal phase at high temperature. Furthermore, the present results demonstrated that TiO2@GC heterojunctions has a great potential to be used as efficient and economical photocatalysts for environmental contaminants remove.

In this work, ZnGa2O4 solar-blind photodetectors (PD) based on a metal-semiconductor-metal (MSM) structure was fabricated by radio frequency (RF) magnetron sputtering method. The transmittance of the material shows larger than 80% cross the visible light region. As a wide bandgap and high transparency semiconducting material, ZGO is a potential candidate for UV-detection applications. The ZGO MSM PD with no oxygen flow during sputtering exhibits a responsivity of 4.46 × 10−2 A/W under illumination at wavelength of 260 nm, rejection ratio of 1.75 × 104. The performance can be enhanced with proper thermal annealing process. With an annealing process at temperature of 200°C, the responsivity and rejection ratio are 0.203 A/W and 1.12 × 105, respectively.

Despite the attractiveness of low temperature hydrothermal processes, the synthesis of vertical ZnO nanostructures has mostly been limited to rigid substrates. Moreover, patterned growth of nanostructures is also commonly carried out on rigid substrates, since conventional optical lithography is not easily applied to polymeric substrates, as focusing and reaction of the substrate with the organic solvent used in the lithography process prove to be a challenge. Here, we demonstrate the limited work on laser writing lithography patterned growth instead of the commonly used soft lithography patterned growth of nanorods on the transparent flexible substrate polyethylene terephthalate (PET) with a practical device demonstration. The visibly-transparent nanorods on the PET platform constitute a superior structural integrity with ohmic electro-conductivity even in a highly bent state. Accordingly, this can pave the way towards integration of vertically-aligned 1D nanostructures on a flexible platform for a transparent, conformable, shock-proof and lightweight product.

In this paper, resistive random-access memory (RRAM) with InGaO (IGO) as an active layer was fabricated by radio-frequency (RF) sputtering system and the resistive switching mechanism with the different top electrode (TE) of Pt, Ti, and Al were investigated. The Pt/IGO/Pt/Ti RRAM exhibits typical bipolar resistive switching features with an average set voltage of 1.73 V, average reset voltage of −0.60 V, average high resistance state (HRS) of 54,954.09 Ω, and the average low resistance state (LRS) of 64.97 Ω, respectively. Ti and Al were substituted for Pt as TE, and the conductive mechanism was different from TE of Pt. When Ti and Al were deposited onto the switching layer, both TE of Ti and Al will form oxidation of TiOx and AlOx because of their high activity to oxygen. The oxidation will have different effects on the forming of filaments, which may further affect the RRAM performance. The details of different mechanisms caused by different TE will be discussed. In brief, IGO is an excellent candidate for the RRAM device and with the aids of TiOx, the set voltage, and reset voltage, HRS and LRS become much more stable.

X-ray absorption near-edge structure ͑XANES͒, extended x-ray absorption fine structures ͑EXAFS͒, and photoluminescence measurements were used to elucidate the microstructural and photoluminescence properties of ZnO nanowires ͑ZnO-NWs͒ that had been treated with Eu by thermal diffusion. The O K-and Eu L 3-edge XANES and EXAFS spectra at the Zn K-and Eu L 3-edge verified the formation of Eu 2 O 3-like layer on the surface of ZnO-NWs. X-ray diffraction, XANES and EXAFS measurements consistently suggest the lack of substitutional doping of Eu ions at the Zn ion sites in the interior of ZnO-NWs. The clear sharp and intense emission bands in the range 610-630 nm of Eu-treated ZnO-NWs originated from the intra-4f transition of Eu ions in the Eu 2 O 3-like surface layer.

In this study, the optical and electrical properties of a zinc tin oxide (ZTO) thin-film transistor (TFT) were investigated. The TFT was fabricated using ZTO as the active layer, which was deposited by a radio frequency magnetron sputtering system, to form an ultraviolet (UV) photodetector. The device has a threshold voltage of 0.48 V, field-effect mobility of 1.47 cm2/Vs in the saturation region, on/off drain current ratio of 2×106, and subthreshold swing of 0.45 V/decade in a dark environment. Moreover, as a UV photodetector, the device has a long photoresponse time, responsivity of 0.329 A/W, and rejection ratio of 3.19×104 at a gate voltage of -15 V under illumination of wavelength 300 nm.

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