Sandwich structure confined gold as highly sensitive and stable electrochemical non-enzymatic glucose sensor with low oxidation potential

Abstract

• Fe 3 O 4 @Au@CoFe-LDH is prepared through a spontaneous galvanic displacement reaction. • In Fe 3 O 4 @Au@CoFe-LDH, the metallic Au intercalates between Fe 3 O 4 and LDH forming the sandwich structure. • Fe 3 O 4 @Au@CoFe-LDH possesses high sensitivity of 6342 μA mM −1 cm −2 , broad linear detection range of 0.0375 to 15.64 mM and low limit of detection of 12.7 μM, with an extremely low oxidation potential of 0.82 V vs. RHE. • The small quantity of Au laying between LDH and Fe 3 O 4 is the active part of glucose oxidation and the existence of Fe 3 O 4 nanoparticles significantly improves the stability of the electrocatalyst. The preparation of highly sensitive and stable non-enzymatic glucose sensors is critical to the prevention and treatment of diabetes. Fe 3 O 4 @Au@CoFe-LDH is prepared through a spontaneous galvanic displacement reaction. A series of structural characterizations testify the successful formation of Fe 3 O 4 @Au@CoFe-LDH electrocatalyst, with the Au intercalating between Fe 3 O 4 and LDH to form the sandwich structure. Cyclic voltammetry tests indicate that Au is responsible for the electrocatalytic oxidation of glucose. The characterizations of the electrochemical sensor for glucose detection indicate that Fe 3 O 4 @Au@CoFe-LDH possesses high sensitivity of 6342 μA mM −1 cm −2 , with an extremely low oxidation potential of 0.82 V vs. RHE. Even with the high glucose concentration of 15 mM, the sensitivity remains at 4359 μA mM −1 cm −2 . Due to the broad linear detection range (0.0375 to 15.64 mM) and the low limit of detection (12.7 μM), Fe 3 O 4 @Au@CoFe-LDH is applicable towards practical application. Thanks to the sandwich structure, which confines the Au in between Fe 3 O 4 and CoFe-LDH, the Fe 3 O 4 @Au@CoFe-LDH glucose sensor shows high long-term stability and satisfactory selectivity. The successful synthesis of the sandwich-structured Fe 3 O 4 @Au@CoFe-LDH provides a new conception for the design of highly sensitive and stable non-enzymatic glucose electrodes.