Search

Two-dimensional layered heterostructures show great potential to develop optoelectronic systems. Here, we have investigated the photoresponse properties of two contact interfaces in few-layer graphene–WSe2 heterostructures. The photoresponsivity of graphene–WSe2 contact interface is about 2.67 mA/W, and the photoresponsivity of WSe2–metal contact interface is about 0.2 mA/W. Photocurrent images show that the two contact interfaces behave differently under drain voltage from − 0.5 V to 0.5 V. The photoresponsivity of one contact interface increases with the drain voltage, and that of the other decreases with the drain voltage. Experimental results and band diagram studies prove that the photoresponse properties of contact interfaces are tuned by small drain voltage. This study will be beneficial for understanding the effect of drain voltage on the heterostructures.

For the first time, novel β-C3N4/CuO composites with superior photocatalytic activity are successfully fabricated via a facile reflux method followed by a thermal process. The morphologies, particle size and microstructure of the synthesized β-C3N4/CuO composites largely depended upon copper chloride and the volume ratio of V water:V ethanol in the mixed precursors. The fabricated β-C3N4/CuO nanoflakes exhibited obviously enhanced visible light photocatalytic activity for the degradation of methylene blue (MB) with an ~3.4 and 1.9 fold increase in efficiency over that of pure g-C3N4 and commercial P25, respectively. The β-C3N4/CuO composite photocatalyst also showed photocatalytic activity for the degradation of methyl orange (MO). Moreover, the β-C3N4/CuO nanoflakes showed almost no loss of photocatalytic activity after three recycles of the degradation of the MB. A multiple synergetic mechanism in β-C3N4/CuO nanoflakes, which is featured by the highly reactive {0 0 2} facets, exposed many active sites of nanoflakes and the efficient charge separation are proposed to account for the distinguished photocatalytic activity. This work provides a facile and cost-effective strategy for designing novel β-C3N4/CuO photocatalysts for application in environmental purification.

Non-uniform photocurrent is usually generated at the overlapped region of the heterostructures, and its potential applications may be hindered by the spatial uniformity issue of the device photoresponse. Here, nearly a uniform photoresponse at the overlapped region of the thermally oxidized Ni and molybdenum disulphide (MoS2) heterostructures is obtained. Further characterizations reveal that several nanometers Ni is rightly under the NiOx layer formed at the surface of the film in the oxidation process. The heterostructures based on layered MoS2/NiOx/Ni with highly conductive bottom Ni show a high uniform photoresponse with an external quantum efficiency (EQE) of 1.4% at 532 nm. Moreover, successful integration of multiple devices suggests a great priority for such a structure for highly integrated uniform photodetectors.

Metal nanoparticles or nanoclusters have been widely used to functionalize semiconductor metal oxide nanostructures-based gas sensors or photodetectors to significantly enhance the device performance. It is crucial to reach a thorough understanding of the interfacial coupling between the metal nanoclusters and the metal oxide nanostructures. Here, in situ X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) have been used to investigate the interfacial interactions between metals (Au and Co) and molybdenum trioxide (MoO3) films. In spite of the high work function ([Formula: see text]6.8[Formula: see text]eV) of the thermally evaporated MoO3 films, only weak interaction is observed at the Au/MoO3 interface. Au clusters or films can remain their neutral and nonchemically reacted state on MoO3 film. In contrast, the interfacial chemical reaction between Co and MoO3 is significantly strong. A band-bending in MoO3 and two interface states have been observed at the Co/MoO3 interface.