Carbon/iron by-product from catalytic methane decomposition as recyclable Fenton catalyst for pollutant degradation

Direct catalytic decomposition of methane (CDM) has been studied as a possible emission-free hydrogen production route for over 100 years. However, the high cost of catalyst regeneration limits its practical applications. Here, we demonstrate that the solid by-product from CDM using Fe ore catalysts comprising carbon nano onions encapsulated with magnetic Fe cores (Fe@C) can serve as efficient and recyclable Fenton catalysts for pollutant degradation. Fe@C/H2O2 has better performance than FeSO4/H2O2 at similar Fe concentrations and can be used to decompose various pollutants. Mechanistic studies reveal that graphitic carbon layers and encapsulated Fe0 contribute to their high catalytic activity. Further, Fe@C can be easily recovered from an aqueous solution and reused due to the encapsulated magnetic Fe particles. Over three reused cycles, Fe@C/H2O2 only yields 1/8 of Fe sludges compared to FeSO4/H2O2, significantly reducing Fe sludge treatment costs. Overall, Fe@C demonstrates excellent application potentials in water and wastewater treatment, making H2 production via CDM economically more viable.