One-step access to bifunctional γ-Fe2O3/δ-FeOOH electrocatalyst for oxygen reduction reaction and acetaminophen sensing

• The γ-Fe 2 O 3 /δ-FeOOH was synthesized via a facile electrochemical method. • The γ-Fe 2 O 3 /δ-FeOOH can act as a promising bifunctional electrocatalyst. • The γ-Fe 2 O 3 /δ-FeOOH shows high electrocatalytic activity for ORR. • The γ-Fe 2 O 3 /δ-FeOOH effectively sensing acetaminophen molecules. Design of advanced materials for multifunctional applications in catalysis is a new and promising research direction to ensure sustainable development. An electrochemical method using pulse alternating current has been applied for the one-step and environmentally benign design of γ-Fe 2 O 3 /δ-FeOOH bifunctional electrocatalyst for oxygen reduction reaction and environmental pollutant detection. The finding γ-Fe 2 O 3 /δ-FeOOH nanocomposite can be regarded as an effective catalyst to enhance electrocatalytic activity toward ORR and acetaminophen (paracetamol) drug detection. The γ-Fe 2 O 3 /δ-FeOOH sensor achieved an excellent analytical performance for amperometric determination of acetaminophen with a wide concentration range (0.05 - 100 μM), low detection limit (30 nM), outstanding long-term stability and high selectivity in the presence of various interfering reagents. In addition, the modified electrode demonstrated high electrocatalytic activity and good durability in alkaline medium for the oxygen reduction reaction. Therefore, γ-Fe 2 O 3 /δ-FeOOH revealed the superior performance due to the synergistic effect between the phases in the iron-based catalyst. The electrosynthesis using pulse alternating current holds great promise for the development of the mixed-phased catalysts for multifunctional applications.