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

Katagiri Kiyofumi

Hayashi Yuki

Yoshiyuki Risa

Inumaru Kei

Uchiyama Tomoki

Nagata Noriyuki

Uchimoto Yoshiharu

Miyoshi Akinobu

Maeda Kazuhiko

Inorganic Chemistry

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 Zn2+ and Ga3+ 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.

Chemistry [ 430 ]

eng

American Chemical Society

Copyright (c) 2018 American Chemical Society

This document is the Accepted Manuscript version of a Published Work that appeared in final form in 'Inorganic Chemistry', copyright c American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.inorgchem.8b02498.

This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。

[ISSN] 0020-1669

[ISSN] 1520-510X

[DOI] 10.1021/acs.inorgchem.8b02498

[PMID] 30295474