Strong Visible Absorption and Broad Time Scale Excited-State Relaxation in (Ga1–xZnx)(N1–xOx) Nanocrystals

Chuang, Chi-Hung; Lu, Ying-Gang; Lee, Kyureon; Ciston, Jim; Duković, Gordana

doi:10.1021/jacs.5b02077

Cited by 20 publications

(27 citation statements)

References 38 publications

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“…5a). 12 These experimental observations are consistent with a model for the visible absorption that involves interband transitions between a higher lying valence band made by intermixing of ZnO and GaN orbitals and a conduction band that originates mostly from Zn and O orbitals. 5b).…”

Section: Resultssupporting

confidence: 87%

“…5b). 12 The spectra in Fig. This ZnO-like absorption becomes stronger compared to visible absorption with increasing x.…”

Section: Resultsmentioning

confidence: 94%

“…14,25,27,30,36,37 At the low-x end of the composition range, the diffuse reectance spectra have similar shapes, with the effect of the composition being simply the red shiing of the spectrum (Fig. 12 Transient absorption spectra of solubilized (Ga 1Àx Zn x )(N 1Àx O x ) nanocrystals with x ¼ 0.73 exhibit both visible and UV ZnO-like bleaches, and their decay traces overlap, indicating that they share electronic character. At the high-x end of the range, however, both the band gap and the spectral shape change with composition (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…At the high-x end of the range, however, both the band gap and the spectral shape change with composition (Fig. 5,8,12 The UV absorption would then originate from transitions from lower lying valence band levels to the same conduction band. The absorption at wavelengths below 390 nm characteristic of ZnO begins to emerge in the spectra of the ZnO-rich samples starting with x ¼ 0.76.…”

Section: Resultsmentioning

confidence: 99%

“…Both the bulk and the nanocrystalline samples exhibit n-type behavior (Fig. 12 Optimization of the device architecture may lead to higher photocurrent values. The bulk (Ga 1Àx Zn x )(N 1Àx O x ) (x ¼ 0.40) electrode produced photocurrents of 1-2 mA cm À2 at 0.5 V, in agreement with previously reported results.…”

Section: Pec Activity Of Bulk and Nanoscale (Ga 1àx Znmentioning

confidence: 99%

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Synthesis and characterization of (Ga_1−xZn_x)(N_1−xO_x) nanocrystals with a wide range of compositions

Lee

Chuang

et al. 2016

J. Mater. Chem. A

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We describe the synthesis and characterization of wurtzite (Ga 1Àx Zn x )(N 1Àx O x ) nanocrystals with a wide range of compositions and a focus on properties relevant for solar fuel generation. (Ga 1Àx Zn x )(N 1Àx O x ), a solid solution of GaN and ZnO, is an intriguing material because it exhibits composition-dependent visible absorption even though the parent semiconductors absorb in the UV. When functionalized with co-catalysts, (Ga 1Àx Zn x )(N 1Àx O x ) is also capable of water splitting under visible irradiation. Here, we examine the synthesis of (Ga 1Àx Zn x )(N 1Àx O x ) nanocrystals to understand how they form by nitridation of ZnO and ZnGa 2 O 4 nanocrystalline precursors. We find that the ZnO precursor is critical for the formation of crystalline (Ga 1Àx Zn x )(N 1Àx O x ) at 650 C, consistent with a mechanism in which wurtzitenucleates topotactically on wurtzite ZnO at an interface with ZnGa 2 O 4 . Using this information, we expand the range of compositions from previously reported 0.30 # x # 0.87 to include the low-x and high-x ends of the range. The resulting compositions, 0.06 # x # 0.98, constitute the widest range of (Ga 1Àx Zn x )(N 1Àx O x ) compositions obtained by one synthetic method. We then examine how the band gap depends on sample composition and find a minimum of 2.25 eV at x ¼ 0.87, corresponding to a maximum possible solar-to-H 2 power conversion efficiency of 12%. Finally, we examine the photoelectrochemical (PEC) oxidation behavior of thick films of (Ga 1Àx Zn x )(N 1Àx O x ) nanocrystals with x ¼ 0.40, 0.52, and 0.87 under visible illumination. (Ga 1Àx Zn x )(N 1Àx O x ) nanocrystals with x ¼ 0.40 exhibit solar PEC oxidation activity that, while too low for practical applications, is higher than that of bulk (Ga 1Àx Zn x )(N 1Àx O x ) of the same composition. The highest photocurrents are observed at x ¼ 0.52, even though x ¼ 0.87 absorbs more visible light, illustrating that the observed photocurrents are a result of an interplay of multiple parameters which remain to be elucidated. This set of characterizations provides information useful for future studies of composition-dependent PEC properties of nanoscale (Ga 1Àx Zn x )(N 1Àx O x ). † Electronic supplementary information (ESI) available: Fitting of XRD patterns in Fig. 2; TEM images of the samples from Fig. 2; XRD patterns, elemental analysis by ICP-OES, and diffuse reectance spectra of the products from nitridation of the starting mixture with x ¼ 0.78 with varying nitridation time; TEM images of the nitrided products of x ¼ 0.06, 0.24, 0.91, and 0.98; XPS spectra of Zn2p 3/2 , O1s, Ga2p 3/2 , and N1s in samples with several compositions; determination of band gap as a function of composition. See

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Section: Resultssupporting

confidence: 87%

“…5b). 12 The spectra in Fig. This ZnO-like absorption becomes stronger compared to visible absorption with increasing x.…”

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Pec Activity Of Bulk and Nanoscale (Ga 1àx Znmentioning

confidence: 99%

See 3 more Smart Citations

Synthesis and characterization of (Ga_1−xZn_x)(N_1−xO_x) nanocrystals with a wide range of compositions

Lee

Chuang

et al. 2016

J. Mater. Chem. A

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Semiconductor Solid‐Solution Nanostructures: Synthesis, Property Tailoring, and Applications

Liu

Yang

et al. 2017

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The innovation of band-gap engineering in advanced materials caused by the alloying of different semiconductors into solid-solution nanostructures provides numerous opportunities and advantages in optoelectronic property tailoring. The semiconductor solid-solution nanostructures have multifarious emission wavelength, adjustability of absorption edge, tunable electrical resistivity, and cutting-edge photoredox capability, and these advantages can be rationalized by the assorted synthesis strategies such as, binary, ternary, and quaternary solid-solutions. In addition, the abundance of elements in groups IIB, IIIA, VA, VIA, and VIIA provides sufficient room to tailor-make the semiconductor solid-solution nanostructures with the desired properties. Recent progress of semiconductor solid-solution nanostructures including synthesis strategies, structure and composition design, band-gap engineering related to the optical and electrical properties, and their applications in different fields is comprehensively reviewed. The classification, formation principle, synthesis routes, and the advantage of semiconductor solid-solution nanostructures are systematically reviewed. Moreover, the challenges faced in this area and the future prospects are discussed. By combining the information together, it is strongly anticipated that this Review may shed new light on understanding semiconductor solid-solution nanostructures while expected to have continuous breakthroughs in band-gap engineering and advanced optoelectronic nanodevices.

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Using Pd as a Cocatalyst on GaN–ZnO Solid Solution for Visible-Light-Driven Overall Water Splitting

Zhang

Han

et al. 2018

Catal Lett

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Strong Visible Absorption and Broad Time Scale Excited-State Relaxation in (Ga_1–xZn_x)(N_1–xO_x) Nanocrystals

Cited by 20 publications

References 38 publications

Synthesis and characterization of (Ga_1−xZn_x)(N_1−xO_x) nanocrystals with a wide range of compositions

Synthesis and characterization of (Ga_1−xZn_x)(N_1−xO_x) nanocrystals with a wide range of compositions

Semiconductor Solid‐Solution Nanostructures: Synthesis, Property Tailoring, and Applications

Using Pd as a Cocatalyst on GaN–ZnO Solid Solution for Visible-Light-Driven Overall Water Splitting

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Strong Visible Absorption and Broad Time Scale Excited-State Relaxation in (Ga1–xZnx)(N1–xOx) Nanocrystals

Cited by 20 publications

References 38 publications

Synthesis and characterization of (Ga1−xZnx)(N1−xOx) nanocrystals with a wide range of compositions

Synthesis and characterization of (Ga1−xZnx)(N1−xOx) nanocrystals with a wide range of compositions

Semiconductor Solid‐Solution Nanostructures: Synthesis, Property Tailoring, and Applications

Using Pd as a Cocatalyst on GaN–ZnO Solid Solution for Visible-Light-Driven Overall Water Splitting

Contact Info

Product

Resources

About

Strong Visible Absorption and Broad Time Scale Excited-State Relaxation in (Ga_1–xZn_x)(N_1–xO_x) Nanocrystals

Synthesis and characterization of (Ga_1−xZn_x)(N_1−xO_x) nanocrystals with a wide range of compositions

Synthesis and characterization of (Ga_1−xZn_x)(N_1−xO_x) nanocrystals with a wide range of compositions