Hydrogen sensing by enzyme-catalyzed electrochemical detection

Hydrogen (H-2) is a possible future alternative to current fossil-based transportation fuels; however, its lower explosive limit in air requires a reliable sensor to detect leaks wherever H-2 is produced, stored, or used. Most current H-2 sensors employ palladium or its alloy as the sensing element, featuring high operating temperature and limited selectivity. In this study, we report using soluble hydrogenase (SH) of aerobic beta-proteobacterium Ralstonia eutropha strain H16 to accomplish ambient, electrochemical detection of H-2. Gas samples were collected in a solution containing SH that catalyzed the oxidation of H-2. The electrons released during the H-2 oxidation reaction were accepted by benzyl viologen (BV2+). The product of the redox reaction, BV+, was then detected using chronoamperometry. Using this sensing scheme, we demonstrate detection of H-2 ranging from 1 to 100%. In addition, enzyme kinetics and the effect of oxygen on signal response were studied. Our results indicate that it is feasible to develop a sensor to detect H-2 in the atmosphere that is based on enzyme-catalyzed electrochemical detection.