Enhanced hydrogen evolution reaction catalysis <i>via</i> ruthenium single-atom decoration on biphenylene: a DFT study

The development of efficient, cost-effective, and durable electrocatalysts for the hydrogen evolution reaction (HER) remains a cornerstone for realizing sustainable hydrogen energy. However, highly efficient catalysts with low cost for the HER are still very limited. In this study, we employ spin-polarized density functional theory calculations to investigate the catalytic performance of ruthenium (Ru) single-atom catalysts (SACs) anchored on a biphenylene (BPN) substrate. It is found that the unique two-dimensional architecture and electronic characteristics of BPN offer a promising platform for hosting isolated metal atoms. The Ru atom is found to preferentially anchor at the C₄ hollow site, yielding a Δ<i>G</i>_H* of -0.093 eV, comparable to H on Pt. Furthermore, two Ru decorated BPN (2Ru-BPN) is energetically stable and used as a double atom catalyst (DAC). The active site in 2Ru-BPN can facilitate multiple hydrogen adsorptions with a Gibbs free energy change of about -0.12 eV, and thus promote the H₂ evolution along the Tafel pathway under thermoneutral conditions. Thus, this work provides a theoretical blueprint for designing high-performance Ru-based SACs and reinforces the potential of BPN as a next-generation catalyst support in hydrogen production.