Alessandra Moncada

Nanostructured electrochemical devices for sensing, energy conversion and storage

Nanostructured materials are attracting growing interest for improving performance of devices and systems of large technological interest. In this work, the principal results about the use of nanostructured materials in the field of electrochemical energy storage, electrochemical water splitting, and electrochemical sensing are presented. Nanostructures were fabricated with two different techniques. One of these was the electrodeposition of the desired material inside the channels of a porous support acting as template. The other one was based on displacement reaction induced by galvanic contact between metals with different electrochemical nobility. In the present work, a commercial polycarbonate membrane was used as template. In the field of the electrochemical energy storage, the attention was focused on lead-acid battery, and it has been found that nanostructured morphology enhances the active mass utilization up to about 80%, with consequent increase of specific energy and cycling rates to unattainable values for the commercial battery. Nanostructured Ni-IrO2 composite electrodes showed valuable catalytic activity for water oxidation. By comparison with other Ni-based electrocatalyst, this electrode appears as the most promising anode for electrochemical water splitting in alkaline cells. Also in the field of sensing, the nanostructured materials fabricated by displacement reaction showed performance of high interest. Some new results about the use of copper nanowires for H2O2 sensing will be showed, evidencing better performance in comparison with copper thin film. In this work, we will show that nanostructured electrodes are very promising candidate to form different electrochemical setups that operate more efficiently comparing to device with flat electrode materials.

Performance of Nanostructured Electrode in Lead Acid Battery

Lead acid batteries have a large number of potential advantages, but the high weight of lead limits their use in new technologies, like hybrid or electrical cars, which require light batteries with high specific energy. We tried to overtake this limit with nanostructured electrodes of PbO2 and Pb, obtained by electrodeposition in polycarbonate template. In the case of lead, to obtain electrodes with very good mechanical stability, a systematic investigation of electrodeposition process was needed to overcome the formation of dendrites that is the principal limitation of electrochemical production of metal lead. Nanostructured electrodes were tested in a zero gap configuration, using commercial plates as counterelectrode and an AGM type separator in a 5M H2SO4 aqueous solution. Electrochemical tests were performed in very stressing conditions, cell was discharged up to 90% of the gravimetric charge of nanostructured electrode up to a cut-off voltage of 1.2 V. Charge/discharge tests were carried out at high C-rate (2C, 5C and 10C) and excellent results have been obtained. After a short stabilization period (about 100 cycles), the nanostructured electrodes are able to work for more than 1,000 cycles with high discharge capacity. These findings indicate that lead-acid batteries made with nanostructured electrodes are able to work at high C-rate, never reached with commercially available lead-acid batteries.