The exchange current density depends critically on the nature of the electrode, not only its structure, but also physical parameters such as surface roughness.  Of course, factors that change the composition of the electrode, including passivating oxides and adsorbed species on the surface, also influence the electron transfer. The nature of the electroactive species (the analyte) in the solution also critically affects the exchange current densities, both the reduced and oxidized form.  
Less important but still relevant are the environment of the solution including the solvent, nature of other electrolytes, and temperature. For the concentration dependence of the exchange current density, the following expression is given for a one-electron reaction:
where:
* : the concentration of the oxidized species
*: the concentration of the reduced species
* : a symmetry factor
* : Faraday constant
* : reaction rate constant