Synthesis of gallium oxynitride nanoparticles through hydrothermal reaction in the presence of acetylene black and their photocatalytic NO_x decomposition

Abstract

Gallium oxynitride (GaON) nanoparticles were synthesized through three steps; (i) hydrothermal treatment of an aqueous solution containing Ga(NO), hexamethylenetetramine (HMT), and acetylene black, (ii) calcination, and (iii) nitridation. The presence of acetylene black in the hydrothermal treatment is effective for the synthesis of GaO nanoparticles after the calcination. The intermediate obtained after the hydrothermal reaction possessed no detectable Ga particles in the TEM observation, although the presence of Ga was confirmed in the EDS measurement. This means that acetylene black (AB), in this study, cannot play a simple role as a template. The GaON nanoparticles obtained from the GaO nanoparticles through nitridation possessed a higher oxygen content than that from GaO obtained by hydrothermal synthesis without acetylene black and the subsequent calcination. The obtained GaON nanoparticles show higher photocatalytic NO decomposition activity than bulk GaON synthesized under the same conditions except without acetylene black in the hydrothermal reaction, because of the longer absorption edge and the higher specific surface area. In addition, the effect of nitridation temperature and time on the obtained GaON nanoparticles and their photocatalytic activity was also investigated. Consequently, nanoparticle morphology of a precursor for GaON is important not only for high surface area but also for high visible-light response.

Utility of ZnGa2O4 Nanoparticles Obtained Hydrothermally for Preparation of GaN:ZnO Solid Solution Nanoparticles and Transparent Films

“…However, the difference between the Zn/Ga and O/N ratios of the nitrided samples in this study are slightly large, if we take the difference of the analyzing methods under consideration. This may be induced by Ga vacancy which is observed in our gallium oxynitride case reported previously, and the O/N ratios of the nitrided samples competed with that of the gallium oxynitride case. Also, higher nitrided rate on the surfaces of the particles than that of the inside may be related to this problem, meaning that the Zn content of the particle surface is smaller than that in the inner of the particles to induce heterogeneous composition.…”

“…Therefore, when we desire synthesis of nanostructured oxynitrides, the method (ii) is more effective. In fact, we successfully synthesized gallium oxynitride nanoparticles by nitridation of Ga 2 O 3 nanoparticles obtained hydrothermally . Because drastic alteration of crystal structure during nitridation sometimes collapses original morphology, judicious selection of oxides precursor is significantly important.…”

Compositional effects on the electrical properties of extremely disordered molybdenum oxynitrides thin films

“…Depending on the potential application, the study of the physical properties of metallic oxynitrides usually is performed in nanoparticles [7] and in thin films [8]. In addition to the doping, the properties of the materials are also affected by the microstructure.…”

Ni-Doped Protonated Layered Titanate/TiO2 Composite with Efficient Photocatalytic Activity for NO x Decomposition Reactions

“…In the presence of water and oxygen, photooxidation was dominant for the mechanism of the NO x decomposition reaction. The hydroxyl radical, ⋅ OH, produced by photooxidation of H 2 O, and the hydroperoxyl radical, ⋅ OOH, generated by the reaction between H + and photoreduced oxygen ( ⋅ O 2− ) were involved in the oxidation of NO to form HNO 3 [35][36][37]. Considering that water and oxygen were contained in the compressed air in the present study, NO was likely to have been decomposed by the photooxidation process.…”