LiNH₂-Based Nitridation Synthesis and Structure Analysis of GaN:ZnO Solid Solutions

The GaN:ZnO solid solution is a visible-light-absorbing material widely developed for photocatalytic applications. For the first time, we demonstrate that a molecular source of LiNH₂ significantly enhances the synthesis of GaN:ZnO solid solutions by leveraging its high reactivity in molten lithium chloride. Most notably, LiNH₂ dramatically accelerates the nitridation reaction of gallium chloride (GaCl₃) and zinc chloride (ZnCl₂) or zinc oxide (ZnO), enabling the rapid formation of GaN:ZnO within just 2 h at a relatively low temperature of 650 °C. This marks a significant improvement over conventional ammonia gas synthesis methods, which typically require more than 10 hours. Furthermore, this approach eliminates the need for toxic ammonia gas and metal nitrate oxidizers, providing a safer and more environmentally sustainable pathway for material synthesis. Comprehensive structural and elemental analyses, including XRD, TEM, and XRF, confirmed the formation of highly crystalline GaN:ZnO solid solutions, revealing varying levels of reaction uniformity at the atomic scale under different zinc sources and Zn/Ga ratio conditions. The light absorption edges of the materials ranged from 500 nm to 650 nm, depending on the zinc content and source. These findings establish a novel and efficient synthesis strategy for GaN:ZnO solid solutions, paving the way for their development in visible-light-driven applications.