A. Ruz-Luna, L. Marín, F. Martín, I. Pavlovic, L. Portocarrero Sánchez
The development of effective and sustainable photocatalysts for air pollution abatement is critical to address both environmental and resource security challenges. In this work, novel MgAlFe layered double hydroxides were synthesised. These materials were combined with graphitic carbon nitride to form heterostructured photocatalysts (MAF/CN) for nitrogen oxides removal under visible light. Partial substitution of Al 3+ with Fe 3+ enhanced visible-light absorption and photocatalytic activity. Notably, the best performance was achieved for the formulation with the lowest Mg:M 3+ ratio (Mg 2 Al 0.25 Fe 0.75 ). The reduced consumption of Mg 2+ and Al 3+ , both of which are considered critical raw materials, aligns with the European Union's objectives on resource efficiency and sustainability. The optimized composite (MAF/CN-5) exhibited a remarkable visible light nitrogen oxide removal efficiency (E NO ≈ 60 %) and complete selectivity (S = 100 %). Electron paramagnetic resonance and radical scavenger studies suggested the operation of a Z-scheme mechanism involving the generation of hydroxyl and superoxide radicals and effective suppression of charge carrier recombination. These photocatalysts also demonstrated excellent stability over multiple cycles. Overall, the Mg 2 Al 0.25 Fe 0.75 /g-C 3 N 4 system represents a promising, low-cost, and critical raw materials-conscious solution for solar-driven nitrogen oxides abatement. The material shows clear potential for real-world application in urban air purification. • Fe 3+ substitution promotes the visible-light activity of MgAl LDHs. • Optimized Mg 2 Al 0.25 Fe 0.75 photocatalyst reduces the use of CRM by 25 %. • Mg 2 Al 0.25 Fe 0.75 /g-C 3 N 4 composite removes 60 % NO under visible light. • Photocatalyst shows 100 % selectivity and long-term stability. • Z-scheme mechanism governs .•OH and •O 2 ˉ radicals formation