Multi-site orbital coupling in Ru-based high-entropy alloy-enabled hydroxyl spillover for enhanced peroxidase-like activity

Peroxidase (POD)-like nanozymes are attracting increasing attention in anti-tumor, antibacterial, disease diagnosis, and environmental applications. However, simultaneously improving the POD-like activity and stability of nanozymes remains a non-trivial challenge. Inspired by the excellent stability and multiple active sites of high-entropy alloys, we design a Ru-based (RuPtIrRhCu) high-entropy alloy nanozyme (HEAzyme) with improved catalytic activity and stability. Benefiting from the strong adsorption capacity of Ru toward hydrogen peroxide (H₂O₂)/hydroxyl (OH) and the collaborative effect induced by the multiple elements, an interesting "hydroxyl spillover" route is triggered on the RuPtIrRhCu HEAzymes. The efficient dissociated adsorption of H₂O₂ and fast transfer of adsorbed hydroxyl (*OH, * denotes the adsorbed state) is achieved, resulting in boosted POD-like activity. The POD-like activity of the HEAzyme remained unchanged for 6 months, exhibiting outstanding stability. A multi-channel colorimetric sensor array was developed to specifically identify eight biological antioxidants, especially for the chiral recognition of l-cysteine (l-Cys) and d-cysteine (d-Cys). This study not only provides an effective, multi-site collaborative mechanism for improving POD-like activity and stability but also extends the horizons and perspectives in nanozymes.