Mesoporous Carbon/α-Fe2O3 Nanoleaf Composites for Disposable Nitrite Sensors and Energy Storage Applications

In this work, we report a novel hydrothermal synthesis of α-Fe 2 O 3 nanoleaf-incorporated mesoporous carbon-chitosan (α-Fe 2 O 3 @MPC-chit) as a versatile disposable sensor for selective electrochemical detection of nitrite and for supercapacitor applications. The newly synthesized α-Fe 2 O 3 @MPC-chit nanocomposite was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, UV, and Raman spectroscopy. The extensive physicochemical characterization reveals the strong immobilization of α-Fe 2 O 3 nanoleaves within the MPC-chit composite. The electrochemical characterization with cyclic voltammetry and impedance spectroscopy using [Fe(CN) 6 )] 3-/4- as a redox probe concludes good electron conductivity and efficient electron transfer behavior of α-Fe 2 O 3 @MPC-chit. The α-Fe 2 O 3 @MPC-chit modified electrode exhibits excellent electrocatalytic activity toward nitrite oxidation. The amperometric method of nitrite detection showed a linear range of up to 200 μmol L -1 . The current sensitivity and detection limit were found to be 0.913 μA μM -1 and 31 nM cm -2 , respectively. The improved catalytic activity of the proposed electrode was endorsed by the synergistic effect of α-Fe 2 O 3 with the MPC-chit composite. The ability of the proposed electrode was demonstrated by the successful detection of nitrite present in tap water, river water, and industrial samples with extensive recovery values. Furthermore, the α-Fe 2 O 3 @MPC-chit modified stainless-steel electrode showed high-performance supercapacitor application and exhibited a large specific capacitance of 380 F g -1 at 1 A g -1 .