Theoretical Insights on ORR Activity of Sn-N-C Single-Atom Catalysts

Abstract

The advancement of efficient and stable single-atom catalysts (SACs) has become a pivotal pursuit in the field of proton exchange membrane fuel cells (PEMFCs) and metal-air batteries (MABs), aiming to enhance the utilization of clean and sustainable energy sources. The development of such SACs has been greatly significant in facilitating the oxygen reduction reaction (ORR) process, thereby contributing to the progress of these energy conversion technologies. However, while transition metal-based SACs have been extensively studied, there has been comparatively less exploration of SACs based on p-block main-group metals. In this study, we conducted an investigation into the potential of p-block main-group Sn-based SACs as a cost-effective and efficient alternative to platinum-based catalysts for the ORR. Our approach involved employing density functional theory (DFT) calculations to systematically examine the catalyst properties of Sn-based N-doped graphene SACs, the ORR mechanism, and their electrocatalytic performance. Notably, we employed an H atom-decorated N-based graphene matrix as a support to anchor single Sn atoms, creating a contrast catalyst to elucidate the differences in activity and properties compared to pristine Sn-based N-doped graphene SACs. Through our theoretical analysis, we gained a comprehensive understanding of the active structure of Sn-based N-doped graphene electrocatalysts, which provided a rational explanation for the observed high four-electron reactivity in the ORR process. Additionally, we analyzed the relationship between the estimated overpotential and the electronic structure properties, revealing that the single Sn atom was in a +2 oxidation state based on electronic analysis. Overall, this work represented a significant step towards the development of efficient and cost-effective SACs for ORR which could alleviate environmental crises, advance clean and sustainable energy sources, and contribute to a more sustainable future.

Tin as a co-catalyst for electrocatalytic oxidation and reduction reactions

“…However, the inherent high surface energy of Sn atoms makes them prone to agglomeration, resulting in a significant decline in their catalytic activity for the ORR. 30 Compared with transition metal elements, the p-block elements lack electronic flexibility and are more addicted to certain oxidation states, which may endow the p-block materials with outstanding stability but high inertness. The addition of Sn to the catalyst even increases the selectivity of the product.…”

Theoretical study of transition metal-doped β12 borophene as a new single-atom catalyst for carbon dioxide electroreduction

“…via different pathways. [11][12][13][14] In contrast to the production of extensively studied C 1 products, the production of intricate C 2 products remains a formidable challenge. This is primarily attributed to the complexity of the reaction mechanism, high overpotentials necessary for the desired products, and the low selectivity required to surmount several critical obstacles.…”