The f abrication of the chips containing four microreactors and the microf luidic platform was based on the protocol described in our previous article, also detailed in SI. In addition, for the experiments with organic solvents we isolated the electrodes f rom the electrolyte using a sulfonated tetraf luoroethylene (Naf ion) based membrane incorporated by spin-coating its commercial solution after the f unctionalization of chip with the 4-A TP molecules. The new conf iguration of our chips minimized the total volume respect our previous publication to 0.9 nl in the partial cell of the WE. This volume was considered in the article to calculate the concentrations of electrochemically generated acid conf ined in the volume of the partial cell of the WE.