Almost a quarter of the energy consumed globally is directly or indirectly related to the use of a catalytic process. Conventional nanoparticle-based catalysts recently witnessed the dawn of its potential successor-heterogeneous single-atom catalysts (SACs), which allow the maximum possible dispersion of metal atoms on the catalyst surface, possess unparalleled electronic structure and geometric configuration, and exhibit, otherwise, exceptional performance in a range of energy-related applications. Herein, we critically review the use of heterogeneous SACs in the generation and conversion of hydrocarbons, oxygenates, H 2 fuel, ammonia, commodity and fine chemicals, and the electrochemical energy storage in and release from batteries. We describe the importance of those energy-related compounds in the current energy infrastructure and discuss how catalysis-in particular, single-atom catalysis-can be used more effectively in each application. At last, general guidelines and trends guiding the future design of stable and efficient single-atom catalysts for sustainable energy transformations are provided.

Unlike nano-structured metal catalysts, supported single-atom catalysts (SACs) contain only atomically dispersed metal atoms hinting at much more pronounced metal-support effects.Herein, we take a series of polyoxometalates supported Pt catalysts as examples to quantitatively investigate the stability of Pt atoms on oxide supports and how the Pt-support interaction influences the catalytic performance. For this entire series, we show that the Pt atoms prefer to stay at a four-fold hollow site of one polyoxometalate molecule, and that the least adsorption energy to obtain sintering resistant Pt SACs is 5.50 eV, which exactly matches the cohesive energy of bulk Pt metal. Further, we compared their catalytic performance in several hydrogenation reactions and simulated the reaction pathways of propene hydrogenation by density functional theory calculations. Both experimental and theoretical approaches 2 suggest that despite the Pt 1 -support interactions being different, the reaction pathways of various Pt1-polyoxometalate catalysts are very similar and their effective reaction barriers are close to each other and as low as 24 kJ/mol, indicating the possibility of obtaining SACs with improved stability without compromising activity. DFT calculations show that all reaction elementary steps take place only on the Pt atom without involving neighboring O atoms, and that hydrogenation proceeds from the molecularly adsorbed H 2 species. Pt-SAC give a weaker H 2 adsorption energy than Pt clusters or surfaces, resulting in small adsorption equilibrium constants and small apparent activation barriers which agree between experiment and theory.

Electrostatic interaction has been demonstrated as a simple and general strategy to protect atomically dispersed metal catalysts. Ionic liquid-stabilized single-atom catalysts (ILSSACs) exhibited considerably enhanced durability and hydrogenation activity for a series of catalysts.

A novel Mo-promoted Ce-Zr mixed oxide catalyst prepared by a homogeneous precipitation method was used for the selective catalytic reduction (SCR) of NO(x) with NH3. The optimal catalyst showed high NH3-SCR activity, SO2/H2O durability, and thermal stability under test conditions. The addition of Mo inhibited growth of the CeO2 particle size, improved the redox ability, and increased the amount of surface acidity, especially the Lewis acidity, all of which were favorable for the excellent NH3-SCR performance. It is believed that the catalyst is promising for the removal of NO(x) from diesel engine exhaust.