Atomically-tailored single atom platforms hold promise for next-generation catalysis

Okinawa Institute of Science and Technology

Catalysts play a vital role in modern society, supporting processes from metallurgy to pharmaceutical production. To reduce environmental impact and maximize efficiency, science has pushed the boundaries between homogeneous and heterogeneous catalysis toward single-atom catalysts. However, working with individual atoms poses enormous challenges: it is difficult to overcome their tendency to aggregate into clusters, especially at temperatures above cryogenic levels, and it is complex to arrange them precisely in specific chemical environments.

An international team of researchers from Istituto di Struttura della Materia, National Research Council (CNR-ISM, Italy), the Okinawa Institute of Science and Technology (OIST, Japan), Empa (Switzerland), and University of Rome Tor Vergata (Italy) has developed an innovative approach to overcome these limitations. Through on-surface synthesis (OSS) enabled by atomic-resolution scanning probe microscopy techniques, the scientists fabricated one-dimensional organic polymers capable of selectively binding metal atoms at well-defined coordination sites. It is the first time that such a polymer-based architecture has been achieved, using periodic side extensions that are carefully designed to provide tunable active sites. The platform marks a major advance in single atom catalysis, paving the way towards more efficient and sustainable next-generation catalysts.

“To achieve maximum catalytic efficiency, we must ensure each atom of our catalyst is accessible to reagents – this isn’t possible in bulk materials or clusters, where inner atoms are hidden. But it’s something nature does extremely well, with enzymes showing extraordinary efficiency and selectivity based off single metal atoms or small clusters within tailored molecular environments,” explains lead author Dr. Marco Di Giovannantonio, head of the ONSET Lab at CNR-ISM and Visiting Researcher at OIST. “Our method opens up a new avenue toward near-enzymatic catalysts, by isolating metal atoms in uniform sites along polymer chains with remarkable stability, even above room temperature. The design is adaptable too, and will work with a range of metals and ligands, bringing about new possibilities in catalysis.”

Theoretical study found that the unique structure of these single-atom platforms enabled significantly stronger binding of gases such as CO, O2, and H2, compared with other commonly investigated structures. This shows the promise of such platforms for obtaining deeper understanding of industrially important catalytic reactions that require selective stabilization of intermediates, such as the conversion of CO2 into valuable products.

“This work not only introduces a new strategy for constructing single-atom catalysts with atomically defined reaction centers, but also lays the foundation for the rational design of organometallic nanomaterials for various future applications,” says Professor Akimitsu Narita, head of the Organic and Carbon Nanomaterials Unit at OIST.