Effect of temperature on the transformation from Zn–Ga layered double hydroxides into (GaN)1−x(ZnO)x solid solution

Wang, Junpeng; Yang, Ping; Wang, Zeyan; Huang, Baibiao; Dai, Ying

doi:10.1016/j.jallcom.2015.08.190

Cited by 9 publications

(12 citation statements)

References 35 publications

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“…The use of Zn-Ga LDH enabled formation of Zn-rich GaN:ZnO. These results agreed well with those of previous papers for the preparation of GaN:ZnO using Zn-Ga LDH [37][38][39][40]. A UV-vis diffuse reflectance spectrum for GaN:ZnO prepared from Zn-Ga LDH and urea (R = 3) by calcination at 800 °C for 4 h is shown in…”

supporting

confidence: 90%

“…Although the authors of previous reports mentioned that the use of Zn-Ga LDH provided products with a uniform arrangement of Zn and Ga, no direct evidence for the uniform atomic composition of the same primary particle was given. [37][38][39][40] Our results suggest that Zn-Ga LDH is able to provide GaN:ZnO with highly uniform atomic composition. The bulk atomic composition of GaN:ZnO calcined at different temperatures was investigated by ICP-OES and is summarized in Table 1.…”

Section: Characterization Structural Information About Samples Was Omentioning

confidence: 68%

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Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

et al. 2018

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A solid solution of GaN and ZnO (GaN:ZnO) is promising as a photocatalyst for visible light-driven overall water splitting to produce H2. However, several obstacles still exist in the conventional preparation procedure of GaN:ZnO. For example, the atomic distributions of Zn and Ga are non-uniform in GaN:ZnO when a mixture of the metal oxides, i.e., Ga2O3 and ZnO, is used as a precursor. In addition, GaN:ZnO is generally prepared under harmful NH3 flow for long durations at high temperatures. Here, a facile synthesis of GaN:ZnO with homogeneous atomic composition via a simple and safe procedure is reported. A layered double hydroxide (LDH) containing Zn 2+ and Ga 3+ was used to increase the uniformity of the atomic distributions of Zn and Ga in GaN:ZnO. We employed urea as a nitriding agent instead of gaseous NH3 to increase the safety of the reaction. Through the optimization of reaction conditions such as heattreatment temperature and content of urea, single-phase GaN:ZnO was successfully obtained. In addition, the nitridation mechanism using urea was investigated in detail. NH3 released from the thermal decomposition of urea did not directly nitride the LDH precursor. X-ray absorption and infrared spectroscopies revealed that Zn(CN2)-like intermediate species were generated at the middle temperature range and Ga-N bonds formed at high temperature along with dissociation of CO and CO2.

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supporting

confidence: 90%

Section: Characterization Structural Information About Samples Was Omentioning

confidence: 68%

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

et al. 2018

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“…Each Si:GZNO plate appears to be an aggregate of smaller crystallites, much like the particles obtained from the ammonolysis of ZnGa-LDH in the absence of a ZnO buffer layer. 29,33 In the absence of a ZnO buffer, Zn volatilization occurs during nitridation, which leaves behind porous features in GZNO particles. The similar morphological features and lower Zn fraction in Si:GZNO than GZNO/Sn:GZNO are consistent with Zn volatilization during nitridation.…”

Section: ■ Introductionmentioning

confidence: 99%

n-Type Doping of Visible-Light-Absorbing (GaN)_1–x(ZnO)_x with Aliovalent Sn/Si Substitutions

2017

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GaN) 1−x (ZnO) x (GZNO) is a visible-light absorber of interest for solar-driven water splitting. Here, n-type doping of the GZNO solid solution by cation substitution with group IV elements Sn and Si is reported for the first time, which was achieved by nitriding ZnGa-layered double hydroxides with SnO 2 or SiO 2 colloids. Characterization of Si-(15 at. %, metals basis) and Sn-(3 and 4 at. %) doped analogues of GZNO revealed the formation of solid solutions, which crystallize into a wurtzite-type structure. The local structure of the Sn dopants was investigated by X-ray absorption spectroscopy which was confirmed to be a Sn(IV) center in a 4-coordinated tetrahedral environment. Structural and spectroscopic analyses were suggestive that Si and Sn are both shallow donors in GZNO. Thus, doping of GZNO with group IV elements provides a potential handle to tune the carrier transport properties of GZNO for photoelectrochemical devices.

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“…This result led researchers to consider synthesis methods capable of further increasing the dissolved amount of ZnO. Syntheses under high pressure14, using nanoparticulate raw material1516, using a Zn/Ga/CO 3 layered double hydroxide1718, and using a ZnGaO precursor1920 were studied, and solid solutions with X = 0.8 to 0.9 were synthesized. In all of the synthesis methods, the band gap tends to decrease with the amount of ZnO added.…”

Section: Resultsmentioning

confidence: 99%

An artificial photosynthesis anode electrode composed of a nanoparticulate photocatalyst film in a visible light responsive GaN-ZnO solid solution system

Imanaka

Anazawa

MANABE

et al. 2016

Sci Rep

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The artificial photosynthesis technology known as the Honda-Fujishima effect, which produces oxygen and hydrogen or organic energy from sunlight, water, and carbon dioxide, is an effective energy and environmental technology. The key component for the higher efficiency of this reaction system is the anode electrode, generally composed of a photocatalyst formed on a glass substrate from electrically conductive fluorine-doped tin oxide (FTO). To obtain a highly efficient electrode, a dense film composed of a nanoparticulate visible light responsive photocatalyst that usually has a complicated multi-element composition needs to be deposited and adhered onto the FTO. In this study, we discovered a method for controlling the electronic structure of a film by controlling the aerosol-type nanoparticle deposition (NPD) condition and thereby forming films of materials with a band gap smaller than that of the prepared raw material powder, and we succeeded in extracting a higher current from the anode electrode. As a result, we confirmed that a current approximately 100 times larger than those produced by conventional processes could be obtained using the same material. This effect can be expected not only from the materials discussed (GaN-ZnO) in this paper but also from any photocatalyst, particularly materials of solid solution compositions.

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Effect of temperature on the transformation from Zn–Ga layered double hydroxides into (GaN)1−x(ZnO)x solid solution

Cited by 9 publications

References 35 publications

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

n-Type Doping of Visible-Light-Absorbing (GaN)_1–x(ZnO)_x with Aliovalent Sn/Si Substitutions

An artificial photosynthesis anode electrode composed of a nanoparticulate photocatalyst film in a visible light responsive GaN-ZnO solid solution system

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Effect of temperature on the transformation from Zn–Ga layered double hydroxides into (GaN)1−x(ZnO)x solid solution

Cited by 9 publications

References 35 publications

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

n-Type Doping of Visible-Light-Absorbing (GaN)1–x(ZnO)x with Aliovalent Sn/Si Substitutions

An artificial photosynthesis anode electrode composed of a nanoparticulate photocatalyst film in a visible light responsive GaN-ZnO solid solution system

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n-Type Doping of Visible-Light-Absorbing (GaN)_1–x(ZnO)_x with Aliovalent Sn/Si Substitutions