A freshly cleaned substrate (gold, indium tin oxide, or glass) was added to the diazonium solution in a clean 20 mL scintillation vial and allowed to stand for the indicated reaction time. The substrate was removed from the vial, rinsed with acetonitrile or water followed by acetonitrile, and transferred immediately to the second reaction solution. 0.1M solutions of nucleophilic coupling partners were used in all cases (ferrocene in CH2Cl2, potassium iodide and hydroquinone in water, βnaphthol in water to which a minimum amount of saturated KOH solution had been added to induce dissolution) After 5 minutes, the sample was removed from the vial, rinsed with copious amounts of acetone, water, and ethanol, then sonicated for 10 minutes in dichloromethane. Due to the delicate nature of screen-printed electrodes, these were used as received without further cleaning and only aqueous solutions were used in deposition experiments, and solutions were dropcast on the screen-printed working electrode and rinsed off with water only followed by blow-drying with a stream of nitrogen.