We are sorry, but NCBI web applications do not support your browser and may not function properly. More information

Results: 5

1.
Figure 1

Figure 1. From: Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts.

Schematic illustration and band diagram of a rationally designed metal-semiconductor-metal photoelectric nanodevice as highly efficient photocatalysts. Here a Pt/n-Si/n+-Si/Ag heterostructure is created in a single nanowire to integrate a nanoscale metal-semiconductor Schottky photodiode (Pt-Si) encased in a protective insulating shell with two exposed metal catalysts (Pt, Ag). The photoexcitation of the semiconductor creates electron-hole pairs that quickly dissociate into separated electrons and holes, which migrate in the opposite directions toward the two ends for desired reduction reaction on Ag and oxidation reaction on Pt, respectively. This nanostructure can function as a standalone photoelectric nanodevice that can be used for highly efficient photocatalytic reactions while maintaining high electrochemical stability with minimal semiconductor degradation.

Yongquan Qu, et al. Nano Lett. ;10(5):1941-1949.
2.
Figure 4

Figure 4. From: Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts.

Formation of Pt/Si/Ag nanowire photodiodes. (a) Schematic illustration of self-catalyzed silver photoreduction. Only long wavelength light (λ>532 nm) were used here to avoid significant homogeneous photodecomposition of AgNO3. (b) Pt/Si nanowire before silver photoreduction. (c) Pt/Si nanowires dispersed in 1mM AgNO3 solution with 0.5 hour light irradiation. (d) Pt/Si/Ag nanowire diode obtained after 3 hours light irradiation in 1mM AgNO3 solution. The scale bars in b–d is 700 nm. (e–g) EDX spectra of three distinct sections (Pt, Si and Ag) of a nanowire photodiode. (h) Plot of the net change of proton concentration with the reaction time. Black square (red triangle) represent the result obtained from 2.2 × 107 Pt/Si (Pt/Si/Ag) photodiodes in 6 ml of 1 mM AgNO3 solution. (i) Plot of the largest total silver volume with the reaction time.

Yongquan Qu, et al. Nano Lett. ;10(5):1941-1949.
3.
Figure 3

Figure 3. From: Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts.

Structural characterization of the nanostructures and photovoltaic performance of individual Pt/Si nanowire photodiodes. (a) SEM image of monolayer of close-packed PS spheres. (b) SEM image of monolayer of non-close-packed PS spheres. (c d) SEM images of top view and cross-sectional view of the as-etched Si nanowires. (e, f) SEM images of top view and cross-sectional view of Si nanowires with nanoholes. (g,h) SEM images of top view and cross-sectional view of Pt-filled Si nanowires. i, TEM image of a dry etched Si nanowire. (j) TEM image of a Si nanowire with a nanohole. (k) TEM image of a Pt/Si nanowire heterojunction. (l) Schematic illustration of the fabricated device of individual Pt/Si nanowire photodiode. (m) SEM image of a Pt/Si nanowire device. To make the device, the Pt section was controlled to be ~3 μm. The spherical tip at the Pt end is resulted from intentionally excessive electrodeposition of Pt. (n) I–V data obtained in dark (black) and under one-sun irradiation (red). Scale bar is 5 μm for d, f, and h, 2 μm for a, b, c, e, g and m, and 700 nm for i–k.

Yongquan Qu, et al. Nano Lett. ;10(5):1941-1949.
4.
Figure 5

Figure 5. From: Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts.

Photocatalytic properties of Pt/Si/Ag photodiode. (a) Photodegradation of indigo carmine (IC) with 1.2 × 108 Pt/Si/Ag photodiodes dispersed in 10 ml of 100 μM IC aqueous solution. The degradation was characterized by the ratio of measured concentration to its original concentration. The triangles represent the photodegradation reaction of IC without photodiodes. The squares represent the same photodegradation reaction of IC with Pt/Si/Ag photodiodes. (b) Estimated QE of Pt/Si/Ag nanowire photodiodes within visible light range. For the reaction, 6×108 Pt/Si/Ag nanowire photodiodes were dispersed in 2 ml of 10 mM IC aqueous solution. The mixture was exposed to a selected wavelength for 30 minutes for each wavelength. (c) Photocatalytic stability of the Pt/Si/Ag photodiodes in the IC degradation reaction. The experiment is carried out with 2.0 × 107 diodes dispersed in 1 ml of 50μM IC solution with the initial 98% degradation of the IC dye. (d) Plot of the total amount of formic acid with respect to the reaction time. In this reaction, 300 sccm CO2 and 300 sccm H2 were bubbled through 40 ml of 0.04 M Na2CO3 solution containing 1× 108 Pt/Si/Ag nanowire photodiodes.

Yongquan Qu, et al. Nano Lett. ;10(5):1941-1949.
5.
Figure 2

Figure 2. From: Rational Design and Synthesis of Freestanding Photoelectric Nanodevices as Highly Efficient Photocatalysts.

Schematic illustration of the synthesis of Pt/Si/Ag nanowire photodiodes. (a) The starting n/n+ silicon wafer with a 360 nm silicon oxide. (b) Formation of close-packed monolayer of polystyrene (PS) spheres by a drop casting method. (c) Formation of non-close-packed monolayer of PS spheres by O2 plasma. (d) Formation of the patterned DRIE etching-mask containing PS spheres and the underneath silicon oxide discs obtained from using an AOE oxide etching recipe. (e) Using DRIE to obtain vertical Si nanowire arrays. (f) Removal of PS spheres and the residue in chloroform and hydrofluoric acid solution. (g) Formation of silicon oxide shell on Si nanowires by baking sample under ambient conditions at 900 °C for 60 min. (h) Spin coating of photoresist AZ 5214 as a protecting layer for the substrate. (i) Exposure of the Si core of the silicon oxide-encased Si nanowires through an O2 plasma process followed by oxide dry etching. j. Drilling of the nanoholes in the Si nanowires by XeF2 dry etching. (k) Pt electrodeposition. l, Removal of photoresist AZ 5214. m, Release of Pt/Si nanowires into solvent through sonication. (n) Self-catalyzed photoreduction of silver by irradiation on freshly released Pt/Si nanowires in AgNO3 aqueous solution.

Yongquan Qu, et al. Nano Lett. ;10(5):1941-1949.

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...
Write to the Help Desk