Single-Atom Catalysis in Heterogeneous Systems

Single-atom catalysis in heterogeneous systems harnesses isolated metal atoms dispersed on solid supports to achieve unrivalled atom-efficiency, selectivity and stability. By reducing metal loadings to the single-atom limit, virtually all active sites become accessible, leading to dramatic enhancements in catalytic performance and resource utilisation. These catalysts bridge the gap between homogeneous and heterogeneous catalysis: they combine the well-defined active sites of molecular catalysts with the robustness and recoverability of solid materials. Key advances in synthetic strategies—such as atomic layer deposition, wet-chemistry trapping and pyrolysis—enable precise anchoring of metal atoms onto oxide, carbon or nitride supports. Characterisation techniques like high-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy and operando spectroscopies reveal the coordination environment, electronic structure and dynamic evolution of single atoms under reaction conditions. Such detailed understanding has paved the way for applications in energy conversion (hydrogen evolution, oxygen reduction, CO₂ reduction), fine chemical synthesis (selective hydrogenation, oxidation) and environmental remediation. Critical challenges remain in preventing atom migration and aggregation under high temperatures or reductive atmospheres, and in achieving high metal loadings without forming nanoparticles. Addressing these issues requires continued innovation in support design, defect engineering and electronic metal–support interactions. Overall, single-atom catalysts demonstrate vast potential to revolutionise sustainable chemical processes by maximising catalytic efficiency while minimising precious-metal consumption.

Research from Nature Portfolio

Recent studies have demonstrated the synthesis of isolated platinum atoms on nitrogen-doped graphene via atomic layer deposition, yielding hydrogen evolution rates up to thirty-seven times greater than commercial nanoparticle catalysts. Detailed spectroscopic and theoretical analyses attribute this enhancement to partially unoccupied 5d orbitals of Pt atoms that promote proton adsorption and hydrogen desorption. Other work has anchored platinum single atoms within the internal surfaces of mesoporous alumina, where coordinatively unsaturated Al³⁺ sites stabilise the metal and preserve activity for selective hydrogenation of dienes and CO oxidation under harsh conditions. More recent investigations have shown that fine control of the oxidation state of single platinum atoms through electronic metal–support interaction can systematically modulate activity in both acidic and alkaline hydrogen evolution reactions. These efforts underscore the importance of tailoring local electronic structure to achieve optimal catalytic performance and long-term durability.

Single-Atom Catalysis in Heterogeneous Systems publication trend

The graph below shows the total number of articles in single-atom catalysis in heterogeneous systems across all publications each year (not limited to Nature Index journals).

Technical terms

Single-atom catalyst (SAC): Catalyst in which individual metal atoms are dispersed on a solid support, maximising utilisation of active sites. Support: Solid material (oxide, carbon, nitride) that anchors and stabilises metal atoms. Metal–support interaction (MSI): Electronic and structural coupling between a metal atom and its support, influencing activity and stability. Atomic layer deposition (ALD): Vapour-phase technique for sequential, self-limiting surface reactions that deposit atomic layers with high precision. Turnover frequency (TOF): Number of reactant molecules converted per active site per unit time, a measure of intrinsic catalytic activity. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM): Imaging technique that provides atomic-resolution visualisation of single atoms on supports. Operando spectroscopy: In situ spectroscopic measurements under real reaction conditions, revealing dynamic changes in catalyst structure and oxidation state.

References

1. Elucidation of single atom catalysts for energy and sustainable chemical production: Synthesis, characterization and frontier science. Progress in Energy and Combustion Science (2023).
2. Ultra-Efficient and Cost-Effective Platinum Nanomembrane Electrocatalyst for Sustainable Hydrogen Production. Nano-Micro Letters (2024).
3. Thermally stable single atom Pt/m-Al2O3 for selective hydrogenation and CO oxidation. Nature Communications (2017).
4. Electronic metal–support interaction modulates single-atom platinum catalysis for hydrogen evolution reaction. Nature Communications (2021).