We observed the dramatic enhancement of the intrinsic spontaneous and stimulated emission as well as the ensuing suppression of defect-related green emission in Au-decorated ZnO microrods. A series of spectral experiments and theoretical analysis demonstrated an electron transfer assisted process by surface plasmon (SP) resonant coupling between the Au nanoparticles and ZnO. The mechanism indicates an approach to enhance the UV emission of ZnO through an extra excitation of visible light similar to that for the defect emission of ZnO. Based on the coupling mechanism, the externally enhanced ultraviolet lasing was further improved from 1.5 to 2.8-fold by adjusting the pumping power of the green light intensity in the Au/ZnO hybrid cavity. This research not only further confirms the SPR-assisted electron transfer process but also offers an approach to improve the intrinsic UV emission even for heavily-defected ZnO through visible light excitation via a nonlinear process.
Plasmonic hot carriers have the advantage of focusing, amplifying, and manipulating optical signals via electron oscillations which offers a feasible pathway to influence catalytic reactions. However, the contribution of nonmetallic hot carriers and thermal effects on the overall reactions are still unclear, and developing methods to enhance the efficiency of the catalysis is critical. Herein, we proposed a new strategy for flexibly modulating the hot electrons using a nonmetallic plasmonic heterostructure (named W18O49-nanowires/reduced-graphene-oxides) for isopropanol dehydration where the reaction rate was 180-fold greater than the corresponding thermocatalytic pathway. The key detail to this strategy lies in the synergetic utilization of ultraviolet light and visible-near-infrared light to enhance the hot electron generation and promote electron transfer for C-O bond cleavage during isopropanol dehydration reaction. This, in turn, results in a reduced reaction activation barrier down to 0.37 eV (compared to 1.0 eV of thermocatalysis) and a significantly improved conversion efficiency of 100% propylene from isopropanol. This work provides an additional strategy to modulate hot carrier of plasmonic semiconductors and helps guide the design of better catalytic materials and chemistries.
Core–shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single‐crystal AlN shell layer with thickness of ≈15 nm is coated uniformly on the single‐crystal ZnO nanowire with diameters of ≈330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 × 103 to 2.05 × 104 A W−1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark ratio and photoresponsivity are 300 and 381 A W−1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.
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