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A simple one-step thermal evaporation of CdSe powder at controlled experimental conditions is designed resulting in the formation of uniform Si-core/CdSe-sheath coaxial cables. Various Si-cored heterostructures which can serve as potential building blocks in various nanodevices can be prepared by this method.

Despite numerous studies on broadband photodetectors, the problematic query that remains unaddressed is the limited photoresponsivity while broadening the spectral regime. Here, for the first time, a rational design of a hybrid 1D CdSe nanobelt/2D PbI 2 flake heterojunction device is constructed, which substantially boosts the photocurrent while significantly attenuating the dark current, resulting in improved photodetector figures-of-merit. Thanks to the excellent quality of the nanobelt/flake and built-in electric field at the CdSe/PbI 2 interface heterojunction, photogenerated carriers are promptly segregated and more photoexcitons are accumulated by the respective electrodes, enabling a high responsivity of ∼10 6 A/W, making this one of the highest values among similar reported hybrid heterojunction photodetectors, together with a large linear dynamic range, superior sensitivity, excellent detectivity and external quantum efficiency, an ultrafast response, and a broadband spectral response range. The similar 1D/2D hybrid heterojunction device architecture assembled on the flexible polyimide tape substrate exhibits excellent folding endurance and mechanical, flexural, and long-term environmental stability. The present device architecture and robust operational stability in an ambient environment reveals that the combination of the present 1D/2D hybrid heterojunction has incredible potential for future flexible photoelectronic devices.

Low-cost multicomponent alloyed one-dimensional (1D) semiconductors exhibit broadband absorption from the ultraviolet to the near-infrared regime, which has attracted a great deal of interest in high-performance flexible optoelectronic devices. Here, we report the facile one-step fabrication of high-performance broadband rigid and flexible photodevices based on multicomponent alloyed 1D cadmium-sulfur-selenide (CdS x Se 1- x ) micro-nanostructures obtained via a vapor transport route. Photoresponse measurements have demonstrated their superior spectral photoresponsivity (5.8 × 10 4 A/W), several orders of magnitude higher than the pristine CdSe nanobelt photodevice, high specific detectivity (2 × 10 15 Jones), photogain (1.2 × 10 5 ), external quantum efficiency (EQE, 1.4 × 10 7 %), rapid response speed (13 ms), and excellent long-term environmental stability. The multicomponent alloyed CdS x Se 1- x nanobelt photodevice demonstrated about three times higher photocurrent as well as can operate under multiple color illuminations (200-800 nm) and at a high applied bias of 10 V with the photoresponsivity and EQE being boosted to 4.34 × 10 5 A/W and 8.96 × 10 7 %, respectively. Furthermore, multicomponent alloyed CdS x Se 1- x nanobelt flexible photodevices show excellent mechanical and flexural photostabilities with identical photoresponse as rigid nanodevices. The improvement mechanism found in the present research can be exploited to lead to the design of high-performance flexible photodevices comprising other multicomponent nanomaterials.

Sodium (Na)- and potassium (K)-doped δ-MnO 2 , which presented different band gaps, were synthesized by a hydrothermal method. Then, uniform Au nanoparticles (NPs) were deposited on MnO 2 to form metal-semiconductor nano-heterojunctions (MnO 2 -Au). By comparing their temperature-dependent thermal catalytic performances, p-aminothiophenol to p, p'-dimercaptoazobenzene conversion was used as proof-of-concept transformations. MnO 2 -Au hybrid materials demonstrated better thermal catalytic performances relative to individual Au NPs. Meanwhile, K-doped MnO 2 -Au, with a MnO 2 support displaying a narrower bandgap, displayed superior catalytic activities relative to Na-doped MnO 2 -Au. To get the same catalytic performance by individual Au NPs, it can be ∼50 K less by Na-doped MnO 2 -Au and ∼100 K less by K-doped MnO 2 -Au. The enhancement is mainly attributed to the thermally excited electrons in MnO 2 , which were transferred to Au NPs. The additional electrons in Au NPs increase the electron density and thus contribute to the improvement of thermal catalysis. Our findings show that the establishment of a nano-heterojunction formed by metal NPs on a semiconductor support has a significant impact on thermal catalysis, where a narrower band gap can facilitate thermally excited carriers and thus bring about better catalytic performances. Thus, the results presented here shed light on the design of a nano-heterojunction catalyst to approach reactions with superior performance under moderate conditions.

Because of the direct band gap of 4.9 eV, β-Ga2O3 has been considered as an ideal material for solar-blind photodetection without any bandgap tuning. Practical applications of the photodetectors require fast response speed, high signal-to-noise ratio, low energy consumption and low fabrication cost. Unfortunately, most reported β-Ga2O3-based photodetectors usually possess a relatively long response time. In addition, the β-Ga2O3 photodetectors based on bulk, the individual 1D nanostructure, and the film often suffer from the high cost, the low repeatability, and the relatively large dark current, respectively. In this paper, a Au/β-Ga2O3 nanowires array film vertical Schottky photodiode is successfully fabricated by a simple thermal partial oxidation process. The device exhibits a very low dark current of 10 pA at -30 V with a sharp cutoff at 270 nm. More interestingly, the 90-10% decay time of our device is only around 64 μs, which is much quicker than any other previously reported β-Ga2O3-based photodetectors. Besides, the self-powering, the excellent stability and the good reproducibility of Au/β-Ga2O3 nanowires array film photodetector are helpful to its commercialization and practical applications.

A facile pulse laser ablation approach for preparing black titanium oxide nanospheres, which could be used as photocatalysts under visible light, is proposed. The black titanium oxide nanospheres are prepared by pulsed-laser irradiation of pure titanium oxide in suspended aqueous solution. The crystalline phases, morphology, and optical properties of the obtained nanospheres are characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and UV-vis-NIR diffuse reflectance spectroscopy. It is shown that high-energy laser ablation of titanium oxide suspended solution benefited the formation of Ti(3+) species and surface disorder on the surface of the titanium oxide nanospheres. The laser-modified black titanium oxide nanospheres could absorb the full spectrum of visible light, thus exhibiting good photocatalytic performance under visible light.