The global transition to sustainable energy production revolves around innovations in electrocatalysis, the cornerstone of energy conversion technologies. Over the years, catalysts have evolved from bulk materials to nanoparticles (NPs) and nanoclusters (NCs), culminating in single-atom catalysts (SACs), which represent the peak of catalyst engineering. SACs have revolutionized electrocatalytic processes by maximizing atom efficiency and offering tunable electronic properties, lowering the energy barrier associated with the absorption and desorption of key reaction intermediates, thus promoting specific reaction pathways. This review delves into the synthesis, characterization, and theoretical modeling of SACs, offering a comprehensive analysis of state-of-the-art methodologies. It highlights recent breakthroughs in diverse electrocatalytic reactions, including the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water splitting, the oxygen reduction reaction (ORR) for Zn-air batteries and fuel cells, the CO2 reduction reaction (CO2RR), and green ammonia synthesis. The discussion emphasizes the unique mechanisms that drive the exceptional performance of SACs, shedding light on their unparalleled activity, selectivity, and stability. By integrating experimental insights with computational advances, this work outlines a path for the rational design of next-generation SACs tailored to a broad spectrum of electrocatalytic applications. While summarizing the current landscape of electrocatalysis by SACs, it also outlines future directions to address the energy challenges of tomorrow, serving as a valuable resource for advancing the field.

• Klíčová slova
• atomically dispersed sites, catalyst engineering, computational modeling, electrocatalytic reactions, metal−support interaction, single-atom catalysis,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

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 use of metal single atoms (SAs) as co-catalysts on semiconductors has emerged as a promising technology to enhance their photocatalytic hydrogen production performance. In this study, we describe the deposition of very low amounts of Pt SAs (<0.1 at %) on exfoliated graphitic carbon nitride (C3N4) by a direct Pt-deposition approach from highly dilute chloroplatinic acid precursors. We find that - using this technique-a remarkably low loading of highly dispersed Pt SAs (0.03 wt %) on C3N4 is sufficient to achieve a drastic decrease in the overall charge transfer resistance and a maximized photocatalytic efficiency. The resulting low-loaded Pt SAs/C3N4 provides a H2 production rate of 1.66 m mol/h/mg Pt, with a remarkable stability against agglomeration; even during prolonged photocatalytic reactions no sign of light-induced Pt agglomerations can be observed. We ascribe the high performance and stability to the site-selective, stable coordination of Pt within the C3N4 structure. Notably the H2 production rate of the low-loaded Pt SAs surpasses the activity of Pt SAs deposited by other techniques or nanoparticles at comparable or even higher loading - the optimized Pt SAs decorated C3N4 show ≈5.9 times higher rate than Pt NP decorated C3N4.

• Klíčová slova
• C3N4, H2 evolution, Pt single atoms, dark deposition, photocatalysis,
• Publikační typ
• časopisecké články MeSH