Piezoelectret Mechanocatalysts for Direct Water Splitting via Ultrasonication

This work reports the first use of polymeric piezoelectret films for direct water splitting using ultrasonication as the driving mechanism. Piezoelectret devices are analogous to piezoelectret ceramic materials which produce electrical charges in response to mechanical stimulus. Water splitting has gained increasing attention as an alternative for producing renewable hydrogen energy. Hydrogen energy has high energy conversion efficiency and does not contribute to the harmful greenhouse gas effect that is responsible for various environmental hazards such as climate change, acid rain, and smog. The piezoelectret device is made of a polymer with charged microscopic dipoles that is bounded by metal electrodes. Ultrasonication is used to produce mechanical stimulus on the device which then generate a voltage on the surface of the metal electrode layers. This voltage catalyzes the water splitting reaction to produce hydrogen from water. Our process achieves water splitting without complicated thermal annealing (in contrast to previous work using piezoelectric ceramics) and does not use complicated transformer circuits. We show voltage measurements from mechanical stimulus to demonstrate that the device voltage can surpass the 1.23 V required to catalyze the water splitting reaction. Additionally, hydrogen quantification is conducted using Gas Chromatography (GC). Based on the analysis, the device has potential for passive energy harvesting of vibrational motion in liquid media such as tidal motions in the ocean.