Metal Single‐Atom Electrocatalysts Excel from Coordination Configuration via Heteroatoms Tuning

Electronic structure modulation of molybdenum-iron double-atom catalyst for bifunctional oxygen electrochemistry

Highly Dispersive Metal Atoms Anchored on Carbon Matrix Obtained by Direct Rapid Pyrolysis of Metal Complexes

Propane Dehydrogenation on Single-Site [PtZn4] Intermetallic Catalysts

Surface synergistic effect of sub-2 nm NiFeCr hydroxide nanodots yielding high oxygen evolution mass activities

Recently, single atom catalysts (SACs) with isolated metal atom as the active site have received extensive attention for their excellent catalytic performance. However, limited by the strong aggregation tendency of monometallic atoms, the construction of SACs remains a formidable challenge. Herein, we developed a facile ternary copolymerization‐pyrolysis approach to synthesize a single cobalt atom catalyst (Co1@NC) by employing amino‐functionalized cobalt phthalocyanine (CoPc(NH2)4) as the metal precursor. Specially, CoPc(NH2)4 was copolymerized with melamine and 1,4‐phthalaldehyde to yield a terpolymer, thereby allowing CoPc to be more uniformly and stably distributed in the polymer network. Subsequently, the obtained terpolymer was pyrolyzed to afford Co1@NC. Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy (AC HAADF‐STEM) and X‐ray absorption spectroscopy (XAS) directly confirmed that the catalyst Co1@NC was a single cobalt atom catalyst. Furthermore, the large specific surface area (SBET = 418.8 m2/g) and high cobalt content (2.71 wt%) of Co1@NC provided more cobalt active sites and therefore displayed excellent catalytic activity in the hydrogenation of nitrobenzene. In addition, the catalyst showed remarkable cyclic stability in five cycles and remained as the single atom catalyst.

Defining the loading of single-atom catalysts: weight fraction or atomic fraction?

Engineering the regulation strategy of active sites to explore the intrinsic mechanism over single‑atom catalysts in electrocatalysis.

Supported atomically dispersed metal catalysts (ADMCs) have received enormous attention due to their high atom utilization efficiency, mass activity and excellent selectivity. Single-atom site catalysts (SACs) with monometal-center as the quintessential ADMCs have been extensively studied in the catalysis-related fields. Beyond SACs, novel atomically dispersed metal catalysts (NADMCs) with flexible active sites featuring two or more catalytically centers including dual-atom and triple-atom catalysts have drawn ever-increasing attention recently. Owing to the presence of multiple neighboring active sites, NADMCs could exhibit much higher activity and selectivity compared with SACs, especially in those complicated reactions with multi-step intermediates. This review comprehensively outlines the recent exciting advances on the NADMCs with emphasis on the deeper understanding of the synergistic interactions among multiple metal atoms and underlying structure–performance relationships. It starts with the systematical introduction of principal synthetic approaches for NADMCs highlighting the key issues of each fabrication method including the atomically precise control in the design of metal nuclearity, and then the state-of-the-art characterizations for identifying and monitoring the atomic structure of NADMCs are explored. Thereafter, the recent development of NADMCs in energy-related applications is systematically discussed. Finally, we provide some new insights into the remaining challenges and opportunities for the development of NADMCs.

Supported metal nanostructures are the most widely used type of heterogeneous catalyst in industrial processes. The size of metal particles is a key factor in determining the performance of such catalysts. In particular, because low-coordinated metal atoms often function as the catalytically active sites, the specific activity per metal atom usually increases with decreasing size of the metal particles. However, the surface free energy of metals increases significantly with decreasing particle size, promoting aggregation of small clusters. Using an appropriate support material that strongly interacts with the metal species prevents this aggregation, creating stable, finely dispersed metal clusters with a high catalytic activity, an approach industry has used for a long time. Nevertheless, practical supported metal catalysts are inhomogeneous and usually consist of a mixture of sizes from nanoparticles to subnanometer clusters. Such heterogeneity not only reduces the metal atom efficiency but also frequently leads to undesired side reactions. It also makes it extremely difficult, if not impossible, to uniquely identify and control the active sites of interest. The ultimate small-size limit for metal particles is the single-atom catalyst (SAC), which contains isolated metal atoms singly dispersed on supports. SACs maximize the efficiency of metal atom use, which is particularly important for supported noble metal catalysts. Moreover, with well-defined and uniform single-atom dispersion, SACs offer great potential for achieving high activity and selectivity. In this Account, we highlight recent advances in preparation, characterization, and catalytic performance of SACs, with a focus on single atoms anchored to metal oxides, metal surfaces, and graphene. We discuss experimental and theoretical studies for a variety of reactions, including oxidation, water gas shift, and hydrogenation. We describe advances in understanding the spatial arrangements and electronic properties of single atoms, as well as their interactions with the support. Single metal atoms on support surfaces provide a unique opportunity to tune active sites and optimize the activity, selectivity, and stability of heterogeneous catalysts, offering the potential for applications in a variety of industrial chemical reactions.

Single Atoms for Energy Applications

In the presence of carbon-based substrates, the mobility of metal atoms is thermodynamically enhanced, leading to the aggregation of single atoms into clusters. To address this challenge, the coordination between isolated metal atoms and nitrogen (Nx) has been utilized to anchor single atoms and prevent aggregation. Among these structures, Fe─N4-C moieties, with atomic-level dispersion, demonstrate promising oxygen reduction reaction (ORR) catalytic activity. However, the strong adsorption of oxygen intermediates on the Fe active sites limits their intrinsic activity. To overcome this, a novel strategy utilizing nitrogen-coordinated Fe single atoms (Fe─N4) is developed to stabilize the metal atoms. Among these structures, the defect-engineered Fe─N4O configuration, Fe single-atom catalyst (Fe SAs/NPGN), is synthesized via ammonia-thermal etching, significantly boosting oxygen reduction reaction (ORR) catalytic performance by providing abundant active sites and a high specific surface area of 2054.39 m2g-1. The defect-synergistic structure further tunes the electronic properties of the Fe sites, facilitating more efficient ORR activity, as validated by experimental results and theoretical calculations. This approach offers a promising pathway for advancing defect-engineered single-atom catalysts for energy applications.

Iron can be found in all mammalian cells and is of critical significance to diverse cellular activities within human bodies. Widespread applications and the underlying chemical and biological funda...

Identifying Key Descriptors for the Single-Atom Catalyzed CO Oxidation

The hydrogen evolution reaction (HER) is critical for water splitting and represents a promising pathway for green hydrogen generation. Developing novel HER catalysts remains essential as major electrocatalysts often involve high costs and low atom utilization efficiency. To overcome these bottlenecks, catalysts with maximized atom efficiency are needed. Single-atom catalysts offer enhanced HER activity per active site through isolated metal atoms on conductive supports, providing low coordination environments that promote high activity and atom efficiency. Building on this concept, dilute alloy structures(1) present an opportunity to optimize metal site distribution and atom arrangements, potentially facilitating improved hydrogen adsorption and hydrogen formation kinetics.To accelerate the discovery of optimized sub-nanocluster electrocatalysts, high-throughput screening(2) as emerged as a powerful approach that enables rapid evaluation of numerous structural candidates. In this work, we have developed a high-throughput combinatorial approach that integrates first-principles density functional theory (DFT) calculations with experimental validation using state-of-the-art nanoprinting techniques at the Materials Discovery Research Institute (MDRI) within the UL Research Institutes. We generated over 1,000 hypothetical alloy structures spanning 10 elemental components, ranging from minimal surface coverage (single-atom alloys) to complete monolayer surface alloys with varied atomic arrangements. The screening protocol evaluates hydrogen adsorption energies across multiple binding sites while simultaneously assessing structural stability against deformation and agglomeration. Our automated calculation workflow identified promising candidates based on optimized adsorption properties and stability criteria.For experimental validation, we utilized a nanoprinter to precisely deposit metal vapor onto host surfaces according to the computational predictions. The nanoprinter at the MDRI employed physical vapor deposition to vaporize different pairs of metals into nanoparticles. This approach enabled the controlled synthesis of specific nanostructures from the computationally identified candidates. Through comprehensive and high-throughput characterization techniques, we confirmed metal loading and local structural environments, followed by electrochemical testing to assess HER performance. By correlating theoretical predictions with experimental results, we established key structure-property relationships governing HER activity in dilute alloys and identified design principles for next-generation electrocatalysts.This systematic approach successfully bridges the gap between theoretical calculations and experimental implementation, providing new insights for developing cost-effective HER catalysts with optimized precious metal utilization. Our study demonstrates the power of high-throughput computational screening in accelerating the discovery and development of advanced electrocatalysts for clean energy applications. References N. Marcella, J. S. Lim, A. M. Płonka, G. Yan, C. J. Owen, J. E. S. van der Hoeven, A. C. Foucher, H. T. Ngan, S. B. Torrisi, N. S. Marinkovic, E. A. Stach, J. F. Weaver, J. Aizenberg, P. Sautet, B. Kozinsky, A. I. Frenkel, Decoding reactive structures in dilute alloy catalysts. Nat. Commun. 13, 832 (2022).B. C. Yeo, H. Nam, H. Nam, M.-C. Kim, H. W. Lee, S.-C. Kim, S. O. Won, D. Kim, K.-Y. Lee, S. Y. Lee, S. S. Han, High-throughput computational-experimental screening protocol for the discovery of bimetallic catalysts. Npj Comput. Mater. 7, 137 (2021). Declaration of competing interest Authors hereby declare that there is no conflict of interest for the research work reported in this abstract.

Ionic Liquid-Stabilized Single-Atom Rh Catalyst Against Leaching