Derivatization of an elemental carbon surface is accomplished by exposing the carbon surface to an aprotic solvent containing a hydrazone molecule of formula (I) or the corresponding salt of formula (II) wherein R1 is an organic group, and R2 is an organic group or hydrogen and decomposing the hydrazone in the presence of elemental carbon to create a carbene moiety of formula (III): which attaches to the carbon surface. The attached groups may be redox active so that the derivatized carbon may be used in an electrochemical sensor.