What effect does the consumption of reactants have in the diffusion layer?

The consumption of reactants in the diffusion layer is critical to understanding how electrochemical reactions proceed. As reactants are consumed during a reaction occurring at the electrode surface, their concentration in the diffusion layer decreases. This reduction in reactant concentration can hinder the availability of those reactants for the ongoing reaction, effectively slowing down the overall reaction rate.

In electrochemical processes, the diffusion layer is the region where the concentration of reactants transitions from a bulk phase (where the concentration is relatively uniform) to the electrode surface, where the reaction is occurring. As the reaction continues, the localized depletion of reactants leads to a lower concentration gradient, which, in turn, decreases the rate at which reactants can diffuse from the bulk solution to the electrode surface. This phenomenon emphasizes the importance of concentration gradients in driving diffusion, which is essential for maintaining a steady reaction rate in electrochemical systems.