Comparative studies of hybrid functional materials based on different carbon structures decorated with nano-magnetite. Suitable application as platforms for enzyme-free electrochemical sensing of hydrogen peroxide

A simple synthesis procedure was designed to obtain hybrid materials based on graphite structures and magnetite nanoparticles. These new structures were characterized using different techniques. The results show that the graphite structures were densely decorated by spherical Fe3O4 nanoparticles. The amount of immobilized magnetite was controlled by the number of defects present in the different pristine graphite materials. The electro-catalytic behavior of modified glassy carbon electrodes, using magnetite-graphite hybrids exhibited an enhanced catalytic ability toward H2O2 reduction. The best response was obtained using graphites with smaller particle sizes (2 pin and 17 mu m), modified with nano-magnetite. The performance of the electrode in terms of sensitivity for H2O2 amperometric detection was (1.1 +/- 0.1) x 10(5) mu A M-1 cm(-2) mg(-1) while the LOD was 0.50 nM at a working potential of -0.200V. These values are comparable to those obtained using carbon nanotubes and metal or metal-oxide based sensors. The new proposed material appears as a very promising alternative for H2O2 non-enzymatic sensors mainly because its low cost and abundance. The comparison between the different carbon substrates highlights the importance of the close contact between carbon and nano-magnetite, which enhances the catalytic behavior of the material. (C) 2017 Elsevier B.V. All rights reserved.