Caffeinated Interfaces Enhance Alkaline Hydrogen Electrocatalysis

The high Pt loading required for hydrogen oxidation (HOR) and evolution (HER) reactions in alkaline fuel cells and electrolyzers adversely impacts the system cost. Here, we demonstrate the use of caffeine as a ‘double-layer dopant’ to enhance both the HER and HOR of Pt electrodes in base. HER/HOR rates increase by fivefold on Pt(111) and are accelerated on Pt(110), Pt(pc), and Pt/C as well. FTIR spectroscopy confirms that caffeine is adsorbed at the Pt surface, forming a self-limiting film through electrochemical deposition. Caffeine films are stable up to 1.0 V vs. RHE and are readily regenerated through caffeine deposition during load/potential cycling. The findings presented here both identify a potential catalyst additive that can mitigate high Pt loadings in alkaline fuel cells and electrolyzers while opening the door to molecular engineering of solid/liquid interfaces for energy storage and conversion.