Structure Analysis and Photocatalytic Properties of Spinel Zinc Gallium Oxonitrides

Boppana, Venkata Bharat Ram; Schmidt, Heather R.; Jiao, Feng; Doren, Douglas J.; Lobo, Raúl F.

doi:10.1002/chem.201101196

Cited by 16 publications

(14 citation statements)

References 58 publications

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“…Interestingly, however, nitridation of pure ZnGa 2 O 4 nanocrystals under these conditions (650 C for 10 h) does not lead to a crystalline wurtzite product, but rather to a material with one very broad peak in the XRD pattern and a similar value of Zn/(Zn + Ga) as the starting material ( Fig. 38,39 By increasing the temperature to 750 C, we see formation of wurtzite with broad peaks indicating a small crystalline domain size. This could correspond to an amorphous material or one with very small spinel domains.…”

Section: Resultsmentioning

confidence: 91%

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: Resultsmentioning

confidence: 91%

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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“…Spinel zinc gallium oxynitrides have been previously observed to coexist with wurtzite oxynitride under certain synthesis conditions. 40,41 Nitrided ZnGa 2 O 4 shows a clear wurtzite pattern at reaction temperatures of 750 °C and above. 24 STEM-EDS mapping of the ZnGa 2 O 4 particles nitrided at 650 °C (see Figure 8d) shows uniform distribution of Zn, Ga, N, and O. Quantification results of seven areas (∼50 × 50 nm) give x value of 0.14 ± 0.01 which is in agreement with 0.13 ± 0.00 obtained from ICP-OES.…”

Section: Resultsmentioning

confidence: 99%

Control of Elemental Distribution in the Nanoscale Solid-State Reaction That Produces (Ga_1–xZn_x)(N_1–xO_x) Nanocrystals

Tongying

Hall

et al. 2017

ACS Nano

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Solid-state chemical transformations at the nanoscale can be a powerful tool for achieving compositional complexity in nanomaterials. It is desirable to understand the mechanisms of such reactions and characterize the local-level composition of the resulting materials. Here, we examine how reaction temperature controls the elemental distribution in (GaZn)(NO) nanocrystals (NCs) synthesized via the solid-state nitridation of a mixture of nanoscale ZnO and ZnGaO NCs. (GaZn)(NO) is a visible-light absorbing semiconductor that is of interest for applications in solar photochemistry. We couple elemental mapping using energy-dispersive X-ray spectroscopy in a scanning transmission electron microscope (STEM-EDS) with colocation analysis to study the elemental distribution and the degree of homogeneity in the (GaZn)(NO) samples synthesized at temperatures ranging from 650 to 900 °C with varying ensemble compositions (i.e., x values). Over this range of temperatures, the elemental distribution ranges from highly heterogeneous at 650 °C, consisting of a mixture of larger particles with Ga and N enrichment near the surface and very small NCs, to uniform particles with evenly distributed constituent elements for most compositions at 800 °C and above. We propose a mechanism for the formation of the (GaZn)(NO) NCs in the solid state that involves phase transformation of cubic spinel ZnGaO to wurtzite (GaZn)(NO) and diffusion of the elements along with nitrogen incorporation. The temperature-dependence of nitrogen incorporation, bulk diffusion, and vacancy-assisted diffusion processes determines the elemental distribution at each synthesis temperature. Finally, we discuss how the visible band gap of (GaZn)(NO) NCs varies with composition and elemental distribution.

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“…Photoluminescence research of coordination polymers with d 10 metal centers and conjugated organic linkers has attracted increasing attention in recent years . Hence, we investigated the solid-state photoluminescence properties of Zn(II) polymers 4 and 5 , together with the free H 2 bdc ligand and bmp at room temperature (Figure S4, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Syntheses, Characterizations, and Properties of Five Interpenetrating Complexes Based on 1,4-Benzenedicarboxylic Acid and a Series of Benzimidazole-Based Linkers

Guo

Zhao

et al. 2012

Crystal Growth & Design

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Five interesting interpenetrating networks, namely, [Co(p-bdc)(beb) 0.5 ] n (1), {[Co(p-bdc)(bmb)]·H 2 O} n (2), {[Co(pbdc)(bmp)]·H 2 O} n (3), {[Zn(p-bdc)(bmp)]·H 2 O} n (4), and [Zn 2 (pbdc) 2 (bmp)(H 2 O) 2 ] n (5) [p-H 2 bdc = 1,4-benzenedicarboxylic acid, beb = 1,4-bis(2-ethylbenzimidazol-1-ylmethyl)benzene, bmb = 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, and bmp = 1,5-bis(2-methylbenzimidazol) pentane], have been synthesized by employing mixed ligands of various benzimidazole-based ligands with p-H 2 bdc. Complex 1 possesses a 2-fold interpenetrating 3D framework with (4 12 ·6 3 )-pcu topology. Complex 2 exhibits a 3-fold interpenetrating 3D network with 6 6 -dia topology, and complex 3 displays a 4-fold interpenetrating 3D diamond network containing Co/bmp left-and right-handed helical chains. Obviously, with the reducing of the steric hindrance of the Ndonor ligand, complexes 1−3 show interpenetrating networks from 2-fold to 3-fold and 4-fold. Complex 4 is isostructural to 3 and also forms a 4-connected 3D framework with a diamond topology. Complex 5 features a 3D framework generated by 2D → 3D interpenetration and exhibits (8 2 ·10) 2 topology. Our study shows that the steric hindrance changing of ligands can tune the final interpenetrating networks directly.

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Structure Analysis and Photocatalytic Properties of Spinel Zinc Gallium Oxonitrides

Cited by 16 publications

References 58 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

Control of Elemental Distribution in the Nanoscale Solid-State Reaction That Produces (Ga_1–xZn_x)(N_1–xO_x) Nanocrystals

Syntheses, Characterizations, and Properties of Five Interpenetrating Complexes Based on 1,4-Benzenedicarboxylic Acid and a Series of Benzimidazole-Based Linkers

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Structure Analysis and Photocatalytic Properties of Spinel Zinc Gallium Oxonitrides

Cited by 16 publications

References 58 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

Control of Elemental Distribution in the Nanoscale Solid-State Reaction That Produces (Ga1–xZnx)(N1–xOx) Nanocrystals

Syntheses, Characterizations, and Properties of Five Interpenetrating Complexes Based on 1,4-Benzenedicarboxylic Acid and a Series of Benzimidazole-Based Linkers

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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

Control of Elemental Distribution in the Nanoscale Solid-State Reaction That Produces (Ga_1–xZn_x)(N_1–xO_x) Nanocrystals