Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts

Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Nano Letters (Impact Factor: 13.59). 04/2010; 10(5):1941-9. DOI: 10.1021/nl101010m
Source: PubMed

ABSTRACT Photocatalysts are of significant interest in solar energy harvesting and conversion into chemical energy. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here we report the rational design of a new generation of freestanding photoelectric nanodevices as highly efficient and stable photocatalysts by integrating a nanoscale photodiode with two redox catalysts in a single nanowire heterostructure. We show that a platinum-silicon-silver nanowire heterostructure can be synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. We further demonstrated that the Schottky diodes exhibited a pronounced photovoltaic effect with nearly unity internal quantum efficiency and that the integrated nanowire heterostructures could be used as highly efficient photocatalysts for a wide range of thermodynamically downhill and uphill reactions including the photocatalytic degradation of organic dyes and the reduction of metal ions and carbon dioxide using visible light. Our studies for the first time demonstrated the integration of multiple distinct functional components into a single nanostructure to form a standalone active nanosystem and for the first time successfully realized a photoelectric nanodevice that is both highly efficient and highly stable throughout the entire solar spectrum. It thus opens a rational avenue to the design and synthesis of a new generation of photoelectric nanosystems with unprecedented efficiency and stability and will have a broad impact in areas including environmental remediation, artificial photosynthesis and solar fuel production.

Download full-text


Available from: Xiangfeng Duan, Sep 26, 2015
26 Reads
  • Source
    • "The design and fabrication of asymmetric microparticles have been an attractive area of researches in the past years, for each unit has dissimilar faces with unique properties [1] [2] [3] [4]. A library of asymmetric microparticles with diverse anisotropy in shape, surface microstructure and chemical functionality has been explored and these microparticles are widely applied in colloidal assembly [5] [6] [7] [8] [9] [10] [11] [12] [13], targeted drug delivery [14] [15] [16], nanocatalyzing [17] [18] [19] [20] and optical devices [21] [22] [23] [24] [25]. The asymmetric microparticles usually possess unique properties, because the combination of the materials brings on the properties that cannot be performed by one single component. "
    [Show abstract] [Hide abstract]
    ABSTRACT: This work demonstrated a facile approach to the fabrication of the multifunctional asymmetric microparticles and heterogeneous overlapped microshells with the aid of stepwise angled colloidal lithography (ACL). The two dimensional non-close-packed silica sphere arrays were used as template for the fabrication. With two-step angled vapor deposition, the asymmetric microparticles were fabricated. Altering the lattice spacing, incidence angle and the azimuthal angle controlled the size and shape of the microshells capped on silica beads. The overlapped heterogeneous microshells were obtained by dissolving the silica template. Varying the incidence angle and depositing duration controlled the overlapping proportion and the thickness of the microshells, which determined the rigidity or flexibility of microshells. The asymmetric microparticles were modified with well-defined capping of various materials, typically noble metals, which makes them possible being building blocks for self-assembly and localized surface plasmon resonance (LSPR) sensors/surface-enhanced Raman scattering (SERS) materials. The heterogeneous microshells with unique ringent hollow and overlapping structure have potential application in self-folding/opening microcontainers, template for multistage catalytic membrane reactor and microphotonic devices.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 07/2012; 405:51–58. DOI:10.1016/j.colsurfa.2012.04.035 · 2.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Real-time evolution of nanoparticles grown at the semiconductor/electrolyte interface formed between a single crystalline n-type GaAs wafer and an aqueous solution of AgNO(3) has been studied by using high-energy synchrotron X-ray diffraction. The results reveal the distinct nucleation and growth steps involved in the growth of anisotropic Ag nanoplates on the surface of the GaAs wafer. For the first time, a quick transit stage is observed to be responsible for the structural transformation of the nuclei to form structurally stable seeds that are critical for guiding their anisotropic growth into nanoplates. Reaction between a GaAs wafer and AgNO(3) solution at room temperature primarily produces Ag nanoplates on the surface of the GaAs wafer in the dark and at room temperature. In contrast, X-ray irradiation can induce charge separation in the GaAs wafer to drive the growth of nanoparticles made of silver oxy salt (Ag(7)NO(11)) and silver arsenate (Ag(3)AsO(4)) at the semiconductor/electrolyte interface if the GaAs wafer is illuminated by the X-ray and reaction time is long enough.
    Nano Letters 09/2010; 10(9):3747-53. DOI:10.1021/nl102458k · 13.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. We show that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. We further demonstrated that the Pt/Si/Ag diodes exhibited highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol were used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen.
    Advanced Functional Materials 09/2010; 20(18):3005-3011. DOI:10.1002/adfm.201000857 · 11.81 Impact Factor
Show more