Light Enhanced Water Dissociation in Bipolar Membranes

Bipolar membrane (BPM) integration can allow robust and abundant materials to be implemented into energy conversion frameworks and purification pathways vital for the development of clean technologies. However, large membrane voltages associated with water dissociation (WD) have hampered widespread adoption. This work investigates an alternative method to reduce the overvoltage associated with WD operation by illuminating the BPM interface in the presence of nanoparticulate catalyst layers that exhibit plasmonic character. The plasmonic character of the catalyst enhanced the field locally near the active catalyst site, lowering the resistance associated with WD as well as the onset potential for WD. Optimal catalyst loadings allowed a balance of light absorption, catalyst activity, and field utilization. Composites of known WD catalysts that exhibited minimal light activity with a plasmonic and WD active material exhibited improvements in the WD resistance of up to 20% upon irradiation. This proof-of-concept work introduces a new paradigm for altering WD activity in BPMs, where the optical activity of WD catalysts can provide further tunability towards efficient WD and alternative energy conversion frameworks.