Eco-Friendly CO2 Method Speeds Multi-Metal Nano Output

Abstract

Multielement nanostructures promise unusual properties but are constrained by crystalline frameworks limiting incorporable cations, and prevailing syntheses rely on harsh conditions restricting practicality. Here we introduce a CO2-enabled, room-temperature route to nanostructures containing up to 30 different metal cations by coengineering cation and anion arrangements in layered-double-hydroxide-derived frameworks. The key principle is anion-cation arrangement control: CO2-derived carbonate acts as a programmable bridging anion that, with larger-radius and higher-valent cations, drives structural reconstruction, suppresses long-range order, and relaxes radius-ratio constraints. This reorganization yields uniform cation mixing, tunable M3+/M2+ balance, and direct metal-carbonate linkages, producing ultrahigh configurational and positional disorder. The synthesis proceeds under ambient conditions in carbonated water, enabling compositional tunability, equimolar incorporation across 30 elements, and scalable, ecofriendly processing that valorizes a greenhouse gas. Leveraging anion-cation coarrangement to expand the composition space offers a general strategy for designing multielement nanomaterials with enhanced functional freedom.

A team of researchers at UNIST, in collaboration with the University of Cologne and Purdue University, has unveiled a rapid, sustainable method to create complex nanomaterials containing up to 30 different metals in just one minute at room temperature. By utilizing carbon dioxide (CO₂)-commonly known as a greenhouse gas-this innovative process provides an eco-friendly way to produce advanced materials with a wide range of technological applications.

Professors Seungho Cho and Sukbin Lee from the Department of Materials Science and Engineering, along with Professor Junghwan Kim from the Graduate School of Semiconductor Materials and Devices Engineering, led the demonstration of this method to synthesize high-entropy nanostructures-materials composed of multi metals that offer enhanced durability and catalytic activity. These properties make them highly promising for use in batteries, semiconductors, and other advanced technologies.

Traditionally, making such multi-metal materials required extremely high temperatures and pressures, which increased production costs and limited scalability. This new approach, however, turns CO₂ dissolved in water into a natural bridge that facilitates the uniform mixing of different metals under ambient conditions.

The process involves bubbling CO₂ into water to produce carbonic acid, which then releases carbonate ions (CO₃²⁻). When hydroxide ions are added, these carbonate ions easily connect with various metal ions-ranging from rare earth elements like neodymium to transition metals like copper and iron-forming nanometer-sized metal carbonate particles in just one minute of stirring.

Figure 1. Schematic of the greenhouse-gas-driven, energy-efficient route for synthesizing compositionally complex nanomaterials.

This method allows for the creation of complex nanomaterials that, according to traditional principles, would be difficult to combine due to differences in atomic size and other factors. Microscopic analysis revealed that these materials have a highly disordered, non-crystalline structure, which could improve their performance in catalytic and energy storage applications.

Professor Sukbin Lee explained, "The disordered structures produced by this method could be beneficial for catalytic reactions and energy storage. We plan to explore various combinations of metals, including catalysts for hydrogen production and battery electrodes."

Professor Seungho Cho highlighted the environmental benefits, stating, "Creating multi-metal nanomaterials at room temperature cuts costs and reduces CO₂ emissions." He further noted, "Our ultimate goal is to develop a flexible, cost-effective process for making a wide range of materials without restrictions on composition-contributing to both technological progress and environmental sustainability."

This collaborative research involved Professor Sanjay Mathur at the University of Cologne, Germany, and Professor Haiyan Wang at Purdue University. Key contributions were made by UNIST researchers Miri Kim and Dr. Min-Ji Kim from the Department of Materials Science and Engineering at UNIST, along with Yizhi Zhang from Purdue University, who served as the study's first author.

The findings of this research were published online in Nano Letters on November 21, 2025. The study has been supported by the National Research Foundation (NRF) of Korea, the Ministry of Science and ICT (MSIT), UNIST InnoCORE program, the Korea Planning & Evaluation of Industrial Technology (KEIT), and the Electronics and Telecommunications Research Institute (ETRI).

Journal Reference

Miri Kim, Min-Ji Kim, Yizhi Zhang, et al., "Greenhouse-Gas-Driven Room-Temperature Synthesis of Compositionally Complex Nanomaterials via Anion-Cation Arrangement Control," (2025).