possessing high photocurrent gain, fast response speed, high photosensitivity, wide response wavelength, and multiband photodetection are highly desired. [1][2][3][4] For this purpose, nanowires with large surface-to-volume ratio and quantum confinement effect show huge advantages over the bulk and thin film counterparts for fabrication of high performance photodetectors. [5][6][7][8][9][10] Since the discovery of carbon nanotubes, there are many reports about the photodetectors based on various 1D inorganic semiconductor nanostructures. For example, Si, Ge, ZnO, Ga 2 O 3 , CdS, ZnSe, CdSe, GaN, GaAs, InAs, CsPbBr 3 , and CsPb 2 Br 5 nanowires/nanobelts were used to fabricate photodetectors and demonstrate excellent photoresponse properties. [11][12][13][14][15][16] However, it is still very challenging to obtain the broad spectral response and high responsivity in these single component nanowire photodetectors due to the constraint of bandgap engineering, light absorptivity, and photogenerated carriers transfer efficiency. [17,18] High-quality semiconductor heterostructure nanowires (HNWs) integration with multicomponent can increase the absorption ability and extend the photoresponse range effectively. Actually, CdS/CdS x Se 1−x axial heterostructure nanowire photodetectors have shown more superior photodetection properties than that of single component CdS or CdS x Se 1−x . However, the controllable synthesis of axial HNWs is elusive and there are only few reports to date. [19,20] Different from the recent CdS/CdS x Se 1−x axial HNWs, which contain heavy-metal Cd element and might be unfavorable for practical application. ZnSe and ZnS with direct bandgap of 2.7 and 3.6 eV at room temperature are promising semiconductor materials for optoelectronics application in the visible and ultraviolet region. [21][22][23] Compared to binary ZnSe and ZnS nanowires, the recent synthesis and optical properties characterization of ZnS x Se 1−x ternary alloy nanostructures demonstrate tunable bandgap and photoluminescence (PL) properties, [24,25] which are similar to CdS x Se 1−x . These results favor the synthesis of ZnS x Se 1−x /ZnSe HNWs that is more friendly to environment and human health. However, to the best of our knowledge, there is not any report about the ZnSe x S 1−x /ZnSe axial heterostructure due to the phase structure, lattice mismatch, and the melting point between ZnSe and ZnS, which makes the epitaxial growth of ZnSe along the Semiconductor heterostructure nanowires (HNWs) are excellent candidates for application in compact optoelectronics devices with high performance due to the heterojunction interface effect. However, the controllable fabrication of high-quality nano-heterostructures is elusive. In this paper, the controllable growth and optoelectronics device application of high-quality ZnS 0.49 Se 0.51 / ZnSe axial HNWs are reported. The as-synthesized HNWs are straight with uniform diameter distribution of 50-100 nm. Microstructural characterization reveals single crystal and abrupt heterojunction int...

Branched nanostructures of semiconductors based on one-dimensional heterostructures have many promising applications in optoelectronics, supercapacitors, photocatalysts, etc. Here, we report a novel branched core/shell CdO/ZnO hetero-nanostructure that resembles a Crimson bottlebrush ( Callistemon Citrinus ) but with intriguing hexagonal symmetry. The nanomaterials were fabricated via an improved one-step chemical vapor deposition method and consist of a CdO wire as the core and ZnO as the shell. With cadmium acting as a catalyst, ZnO nanowires grow as perpendicular branches from the CdO/ZnO one-dimensional core/shell structure. The nanostructures were characterized with X-ray diffraction scanning and transmission electron microscopy. A homogeneous epitaxial growth mechanism has been postulated for the formation of the nanostructure. The materials show a broad and strong absorption ranging from visible to ultraviolet and a better photoelectrocatalytic properties in comparison to pure ZnO or CdO. Our synthetic strategy may open up a new way for controlled preparation of one-dimensional nanomaterials with core/shell heterostructure, which could find potential applications in solar cells and opto-electrochemical water-splitting devices.