The precise engineering of vacancies in nitrogen-doped graphene (NG) presents a promising strategy for stabilizing metal single-atom catalysts (SACs) and tuning their catalytic performance. We explore the role of vacancies in NG for stabilizing iron-based SACs (Fe-SACs) by using density functional theory (DFT). First, we examine the stability of various vacancy types in graphene and NG supports, addressing the question of preferential formation of specific structural defects as potential sites for metal binding. We reveal simple rules governing the stability of vacancies and show that nitrogen doping can bring about vacancy healing. We identify preferred binding sites for Fe atoms/ions, specifically single and double vacancies, and analyze how the nitrogen-doping pattern in a vacancy affects the interaction of Fe with the SAC support. The results show that the positions of nitrogen(s) and the local charge environment significantly influence the stability of the Fe-SACs. Notably, some Fe@NG configurations, although not the most thermodynamically stable, exhibit enhanced catalytic performance, particularly for a CO2 reduction reaction (CO2RR). These findings offer valuable insights into vacancy engineering as a strategy for designing high-performance Fe-SACs and emphasize the interplay among vacancy types, nitrogen concentration, and catalyst stability in driving the catalytic behavior.

• Klíčová slova
• Activity, CO2RR, SAC, Single-atom catalysis, Stability,
• Publikační typ
• časopisecké články MeSH

The development of single-atom catalysts (SACs) with site-specific and tunable catalytic functionalities remains a highly desirable yet challenging goal in catalysis. In this study, we report a SAC featuring anisotropic coordination cavities synthesized via a one-step polymerization of 2,6-diaminopyridine and cyanuric chloride. These cavities provide a robust framework for anchoring isolated Pd single atoms with exceptional stability. The unique broken symmetry of the catalyst's local structure enables precise control over reaction pathways, allowing reactivity to be switched between distinct catalytic outcomes. Specifically, under tailored reaction conditions, the catalyst can either halt at the borylation step or proceed seamlessly to Suzuki coupling in a self-cascade process. Mechanistic studies unveil the pivotal role of Pd single atoms in driving key steps, including oxidative addition, base exchange, and reductive elimination. Furthermore, green metrics demonstrate the process's sustainability, with minimized waste generation and reduced reliance on hazardous reagents in the self-cascade transformation. This work establishes an innovative benchmark in the field of single-atom catalysis: by enabling complex, multistep transformations via strategic activation of multiple functional groups, this catalyst exemplifies the potential of self-cascade processes to revolutionize synthetic chemistry via catalysis engineering.

• Publikační typ
• časopisecké články MeSH

Single-atom (SA) cocatalysts (SACs) have garnered significant attention in photocatalysis due to their unique electronic properties and high atom utilization efficiency. This review provides an overview of the concept and principles of SA cocatalyst in photocatalysis, emphasizing the intrinsic differences to SAs used in classic chemical catalysis. Key factors that influence the efficiency of SAs in photocatalytic reactions, particularly in photocatalytic hydrogen (H2) production, are highlighted. This review further covers synthesis methods, stabilization strategies, and characterization techniques for common SAs used in photocatalysis. Notably, "reactive deposition" method, which often shows a self-homing effect and thus achieves a maximum utilization efficiency of SA cocatalysts, is emphasized. Furthermore, the applications of SA cocatalysts in various photocatalytic processes, including H2 evolution, carbon dioxide reduction, nitrogen fixation, and organic synthesis, are comprehensively reviewed, along with insights into common artifacts in these applications. This review concludes by addressing the challenges faced by SACs in photocatalysis and offering perspectives on future developments, with the aim of informing and advancing research on SAs for photocatalytic energy conversion.

• Klíčová slova
• cocatalyst, hydrogen production, photocatalysis, single atom,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH