Making metal–organic frameworks easier to shape for electronic devices

In 1974, the University of Melbourne’s chemistry Professor Richard Robson had the idea of replacing the wooden balls and metal rods used in structural models with molecules and chemical bonds. He began experimenting with copper ions linked by a four-armed organic molecule, creating a structure with a cavity. His work laid the foundation for metal–organic frameworks (MOFs), a class of porous materials formed by linking metal ions with organic molecules. Their pores can capture pollutants, support chemical reactions, and store gases, giving MOFs a wide range of potential applications. 

MOFs exhibit exceptional properties arising from their porous structures that are difficult to achieve with conventional materials, enabling applications such as gas storage, separation, and pollutant capture. These unique properties also make MOFs promising candidate for functional devices, such as chemical sensors and electronic devices. However, their delicate structures can be damaged during dry etching, a process that uses energetic particles, such as ion or electron beams, to remove material and create patterns. 

Researchers from Tokyo University of Science (TUS), Japan, have developed a method to reduce this damage by filling MOF pores with an ionic liquid. The ionic liquid increases the material's hardness and helps preserve its structure during etching, enabling the creation of precise patterns at the scale of hundreds of nanometres. 

The study, scheduled for publication in the journal Communications Materials on November 10, 2026, was led by Assistant Professor Yumeng Zheng and Professor Kentaro Kinoshita from the Department of Applied Physics, TUS. Building on Prof. Kinoshita team's earlier work demonstrating that ionic liquids can strengthen the structure of MOFs, the researchers explored whether this approach could also enable precise microfabrication. 

“In this study, we developed a simple method for room-temperature dry etching of this fragile class of materials. By infiltrating MOFs with ionic liquids, their mechanical stability is greatly improved, and the damage from electron and ion beams is reduced, achieving harmless ion beam etching,” says Dr. Zheng. 

The researchers filled Cu3BTC2, a copper-based MOF in which BTC stands for benzene-1,3,5-tricarboxylic acid, with four imidazolium-based ionic liquids that occupied 50–60% of its pore volume. They then used a focused gallium ion beam to etch patterns into the material at room temperature. 

Without the ionic liquid, the ion beam damaged the MOF's crystal structure, creating large cavities. In contrast, the ionic liquid-filled samples showed substantially less apparent microstructural damage under the tested conditions. Using this method, the researchers created various patterns, including a square measuring 5 × 5 µm2, a pillar, and even a Chinese character with etched lines 130–300 nm wide. 

The researchers suggest that ionic liquids protect the MOF by absorbing heat and helping dissipate electrical charge that accumulates during ion beam exposure. Their thermal properties may help buffer temperature changes, while the redistribution of ions may screen local electric field. In addition, thermal analysis showed that the treated MOFs decomposed at higher temperatures than the untreated material, indicating improved thermal stability. Hardness tests also showed that all four ionic liquid-treated samples were harder than the untreated MOF, while their stiffness remained largely unchanged. 

Until now, cryogenic etching has been the only known approach to physically etching MOFs while preserving their delicate structures. Although demonstrated using a copper-based MOF, the new method could potentially be extended to other MOFs, allowing them to be patterned at room temperature without the specialized equipment required for cryogenic cooling with liquid nitrogen. The researchers say this method could make MOFs easier to incorporate into practical devices. 

“We can foresee applications in high-sensitivity sensors, separation and analysis devices, and catalytic devices. This technology has the potential to become a foundational technology for bridging the exceptional material functionalities of MOFs with their use in practical devices,” says Prof. Kinoshita. 

With around 100,000 MOFs known today, this method could extend their applications by making it easier to shape these materials into precise, complex structures. 

Reference  
Title of original paper: Ionic-liquid-assisted room-temperature dry etching of metal–organic frameworks  
Journal: Communications Materials   
DOI: https://doi.org/10.1038/s43246-026-01396-3  

About The Tokyo University of Science 
Tokyo University of Science (TUS) is a well-known and respected university, and the largest science-specialized private research university in Japan, with four campuses in central Tokyo and its suburbs and in Hokkaido. Established in 1881, the university has continually contributed to Japan's development in science through inculcating the love for science in researchers, technicians, and educators.  

With a mission of “Creating science and technology for the harmonious development of nature, human beings, and society," TUS has undertaken a wide range of research from basic to applied science. TUS has embraced a multidisciplinary approach to research and undertaken intensive study in some of today's most vital fields. TUS is a meritocracy where the best in science is recognized and nurtured. It is the only private university in Japan that has produced a Nobel Prize winner and the only private university in Asia to produce Nobel Prize winners within the natural sciences field.  
Website: https://www.tus.ac.jp/en/mediarelations/ 

About Assistant Professor Yumeng Zheng from Tokyo University of Science, Japan 
Dr. Yumeng Zheng is an Assistant Professor in the Department of Applied Physics, Faculty of Advanced Engineering at Tokyo University of Science, Japan. She holds a PhD from Doshisha University. Her research focuses on electronic materials, particularly resistive switching, interface and defect physics, and emerging materials for next-generation memory applications. 

About Professor Kentaro Kinoshita from Tokyo University of Science, Japan 
Dr. Kentaro Kinoshita is a Professor in the Department of Applied Physics, Faculty of Advanced Engineering, at Tokyo University of Science. He received his PhD from the University of Tokyo. His research spans electronic device physics, the development of next-generation devices, and the physical properties and applications of functional materials, including metal–organic frameworks and ionic-liquid-based systems. 
Laboratory: https://www.rs.tus.ac.jp/kinolab/  

Funding information 
This work was partly supported by JSPS KAKENHI Grant Number 26K00987.