Bubble growth and departure modes on wettable/non-wettable porous foams in alkaline water splitting

By Ryuichi Iwata, Lenan Zhang, K. Wilke, S. Gong, Mingfu He, Betar M. Gallant, Evelyn Wang. Joule, 2021

325 citations recorded by the source corpus.

Summary Bubble growth and departure are ubiquitous phenomena in gas-evolving reactions, which govern the overall energy and mass transport. However, an in-depth understanding of the relationship between bubble dynamics and the electrochemical processes, in particular, the wettability effect on a gas-evolving porous electrode remains elusive. Here, we report the bubble dynamics and overpotential observed during alkaline water splitting on a polytetrafluoroethylene (PTFE) deposited nickel porous electrode. A slight decrease in hydrophilicity induced a drastic transition of bubble dynamics and a significant increase of the transport overpotential. We show that the porous electrode transitioned from a liquid-filled state to a gas-filled state when varying the wettability, which changed the bubble departure sizes and bubble coverage. As a result, there were substantial changes of the transport overpotential. Our work elucidates the fundamental relationship between wettability and water splitting characteristics, which provides a practical scenario for structuring the electrode for gas-evolving reactions.

Subfields: Materials Chemistry, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/a93dcdd532cd45182eb4d5d618298d66b3ad4667