Résumé:
The replacement of precious metal electrocatalysts by highly active and cost-efficient alternatives for complete water splitting at low voltage has recently attracted a growing attention. In this work, we reported how semi-graphitized carbons are transformed into highly active electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Although graphite and unmodified carbon are generally inactive as an electrocatalyst for water splitting, the low temperature heat treatment (1h at 400 °C) of defective carbon or partially graphitized carbon can lead to a great improvement in electrocatalytic activity and very remarkably particularly in the case of the hydrogen evolution reaction (HER). More specifically, a direct correlation between structural and composition defects, specific surface area and
electrochemical performance can be established. The best carbon material for water splitting which provides a high current density at relatively low potentials has also been used as a support for the α-Fe2O3 nanoparticles which have been prepared using olive leaves. It has been found that the current density for the OER can be improved by this decoration due to the synergy of the high surface, the good conduction, the defects and the catalytic effect of α-Fe2O3.
