Fig 1.
(a) SEM image of the Mn3O4 nanorods, (b) FTIR spectrum of the as-prepared Mn3O4 nanorods, (c) XRD pattern of the as-prepared Mn3O4 nanorods, and (d) schematic diagram for the development of the direct urea fuel cell based on Mn3O4 nanorods modified ITO electrode.
Fig 2.
Cyclic voltammograms of (a) Mn3O4 nanorods modified ITO electrode in the presence of 1 mol L-1 of KOH, (b) Mn3O4 nanorods modified ITO electrode in the presence of 1 mol L-1 of urea in the absence of KOH, (c) Mn3O4 nanorods modified ITO electrode in the presence of 1 mol L-1 of urea and 1 mol L-1 of KOH, (d) Mn3O4 nanorods modified ITO electrode in the presence of 1 mol L-1 of urea and 2 mol L-1 of KOH, and (e) Mn3O4 nanorods modified ITO electrode in the presence of 1 mol L-1 of urea and 5 mol L-1 of KOH. Scan rate 100 mV/s.
Fig 3.
(a) Cyclic voltammograms of 1 mol L-1 of urea in the presence of 1 mol L-1 of KOH at Mn3O4 nanorods modified ITO electrode under different scan rates within a range from 10 mV/s to 200 mV/s, and (b) the relationship between the redox current values and the square root of the scan rate.
Table 1.
Activity of different electrodes towards urea electrooxidation vs Ag/AgCl.
Fig 4.
(a) Cyclic voltammograms of different concentrations of urea within a range from 0.4 mol L-1 to 4 mol L-1 in the presence of 1 mol L-1 of KOH at Mn3O4 nanorods modified ITO electrode (potential window from -0.5 V to 1 V), inset Square wave voltammograms of different concentrations of urea within a range from 0.4 mol L-1 to 4 mol L-1 in the presence of 1 mol L-1 of KOH at Mn3O4 nanorods modified ITO electrode (potential window from -0.5 V to 0.2 V), and (b) the relationship between the urea concentrations and oxidation current peaks. Scan rate 100 mV/s against Ag/AgCl electrode.
Fig 5.
(a) Square wave voltammograms of different concentrations of urea within a range from 0.4 mol L-1 to 5 mol L-1 in the presence of 1 mol L-1 of KOH at Mn3O4 nanorods modified ITO electrode, and (b) the relationship between the urea concentrations and oxidation current peaks. Scan rate 100 mV/s against Ag/AgCl electrode.
Fig 6.
(a) Cyclic voltammograms of 1 mol L-1 of urea in the presence of 1 mol L-1 of KOH at Mn3O4 nanorods modified ITO electrode over 150 cycles, (b) the relationship between the oxidation current peaks and the cycle number. Scan rate 100 mV/s against Ag/AgCl electrode, (c) the chronoamperometry response of 1 mol L-1 of urea in the presence of 1 mol L-1 of KOH over 30 min, and (d) SEM image of the modified ITO electrode after its uses for electrooxidation of urea.