Fe/Au galvanic nanocells to generate self-sustained Fenton reactions without additives at neutral pH

Abstract

The generation of reactive oxygen species (ROS) via the Fenton reaction has received significant attention for widespread applications. This reaction can be triggered by zero-valent metal nanoparticles by converting externally added H₂O₂ into hydroxyl radicals (˙OH) in acidic media. To avoid the addition of external additives or energy supply, developing self-sustained catalytic systems enabling onsite production of H₂O₂ at a neutral pH is crucial. Here, we present novel galvanic nanocells (GNCs) based on metallic Fe/Au bilayers on arrays of nanoporous silica nanostructures for the generation of self-sustained Fenton reactions. These GNCs exploit the large electrochemical potential difference between the Fe and Au layers to enable direct H₂O₂ production and efficient release of Fe²⁺ in water at neutral pH, thereby triggering the Fenton reaction. Additionally, the GNCs promote Fe²⁺/Fe³⁺ circulation and minimize side reactions that passivate the iron surface to enhance their reactivity. The capability to directly trigger the Fenton reaction in water at pH 7 is demonstrated by the fast degradation and mineralization of organic pollutants, by using tiny amounts of catalyst. The self-generated H₂O₂ and its transformation into ˙OH in a neutral environment provide a promising route not only in environmental remediation but also to produce therapeutic ROS and address the limitations of Fenton catalytic nanostructures.