Unlocking the potential of anti-perovskites through a convenient one-step synthesis route

Although perovskites have attracted a lot of attention lately, anti-perovskites hold just as much potential as functional materials. Bearing a similar crystal structure to perovskites but with an inverted electrical configuration, anti-perovskites exhibit peculiar properties that could be exploited, including negative thermal expansion, ionic conductivity, and even superconductivity. Unfortunately, thus far, synthesizing nanosized anti-perovskites has proven difficult, which is holding back these promising materials in catalytic applications.  

In a recent study published in the Journal of Materials Chemistry A, a research team led by Professor Yuji Iwamoto from the Department of Life Science and Applied Chemistry at Nagoya Institute of Technology, Japan, tackled the current challenges plaguing the synthesis of nitride-based anti-perovskites. They demonstrated a convenient synthesis technique to produce a nanocomposite material consisting of amorphous silicon nitride (a-SiN) ceramic with embedded nanometer-sized Ni₃InN anti-perovskite crystals. Their work, which was made available online on December 28, 2023, and will be published in Issue 6 of the journal in 2024, was co-authored by Young International Faculty (Visiting Faculty) Shotaro Tada and Professor Ravi Kumar from the Department of Metallurgical and Materials Engineering at Indian Institute of Technology Madras (IIT Madras), India, and Director of Research Samuel Bernard from the University of Limoges, France.

The proposed synthesis method can be classified as a ‘Polymer-Derived Ceramics’ (PDCs) route. First, polysilazane—used as a silicon nitride precursor—is chemically modified to include NiCl₂ and InCl₃ molecules. Then, through pyrolysis in an ammonia (NH₃) atmosphere at a relatively low temperature of 300 °C, the modified precursor is transformed into the a-SiN matrix with embedded anti-perovskites in a single step. “While our research team has previously developed a synthesis route for transition metal/a-SiN nanocomposites using polysilazanes modified with transition metal chlorides, this recent study presents a novel approach adopting multiple metal species, resulting in the in situ growth of Ni₃InN intermetallic nanoparticles within an amorphous matrix,” highlights Prof. Iwamoto.

Dr. Tada elaborates: "During the initial stages of the research, we encountered difficulties in obtaining a single-phase Ni₃InN compound through stoichiometric blending. Through systematic analysis using different types of polysilazanes and spectroscopic studies, we found that the presence of vinyl groups in polysilazanes weakened the interaction with InCl₃ due to steric hindrance, leading to enhanced migration of In sources into pre-formed Ni nanoparticles at lower temperatures. We addressed this problem by adding excess InCl₃, resulting in the formation of a single phase Ni₃InN."

This bottom-up synthesis strategy has several strengths. First, the resulting nanocomposite material is highly microporous and contains abundant interfaces between Ni₃InN and the a-SiN matrix. Thus, it enables the modification of the electronic structure of the surfaces of the anti-perovskite nanoparticles formed in situ. Additionally, as a single-step low-temperature method, it provides a straightforward route to obtain complex, highly functional materials.

The researchers also showcased, as a proof of concept, the ability of the a-SiN/Ni₃InN composite to adsorb and desorb CO₂, which could be key to activating and transforming small molecules into value-added compounds for clean energy applications. “This type of nanocomposite, with its diverse multi-metal composition, exhibits promising potential for heterogeneous catalyst design. By providing structural diversity and modifiability, it could facilitate the discovery of new catalytic functionalities,” remarks Dr. Bernard.

Let us hope that these exciting findings pave the way to versatile materials with sustainable applications.

About Nagoya Institute of Technology, Japan

Nagoya Institute of Technology (NITech) is a respected engineering institute located in Nagoya, Japan. Established in 1949, the university aims to create a better society by providing global education and conducting cutting-edge research in various fields of science and technology. To this end, NITech provides a nurturing environment for students, teachers, and academicians to help them convert scientific skills into practical applications. Having recently established new departments and the “Creative Engineering Program,” a 6-year integrated undergraduate and graduate course, NITech strives to continually grow as a university. With a mission to “conduct education and research with pride and sincerity, in order to contribute to society,” NITech actively undertakes a wide range of research from basic to applied science.

Website: https://www.nitech.ac.jp/eng/index.html

About Professor Yuji Iwamoto from Nagoya Institute of Technology, Japan

Yuji Iwamoto is a Professor at the Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Japan. His expertise lies in the field of inorganic materials, especially precursor-derived nanocomposites, organic-inorganic hybrids, and their functional properties. He received the prestigious Richard M. Fulrath Award in 2006 and became a Society Fellow of the American Ceramic Society in 2022. Some of his ongoing research projects delve in the topics of gas separation membranes and functional ceramics for clean energy applications. His academic affiliations include the American Chemical Society and the Materials Research Society. He has published over 200 articles in reputed journals.

About Dr. Shotaro Tada from Indian Institute of Technology Madras, India

Shotaro Tada earned his Ph.D. in applied chemistry from Nagoya Institute of Technology in 2021. He is now a visiting faculty member of the Department of Metallurgical and Materials Engineering at the Indian Institute of Technology Madras. He has participated in several national and international collaborative research projects by proposing creative solutions using his experimental expertise. He is a self-motivated and enthusiastic scientist in materials chemistry, especially in ceramics processing and novel functional materials design (catalysis, nano-composites, and membranes) through a molecular precursor approach. His current research interests lie in small molecule activation and subsequent transformation of small molecules, e.g., hydrogen (H₂) and carbon dioxide (CO₂), into value-added products on the surface of metal-free ceramic materials designed as a catalytic reaction field.