Dissolved Hydrogen Voltammetric Probe and Its Application for Photosynthetic Bacterial Hydrogen Production Rate Evaluation

As known, the dissolved hydrogen undergoes electrochemical oxidation, the mechanism of which depends on the electrolyte pH. In alkaline solutions the OH^- participates in the hydrogen oxidation according to the reaction: H+ OH^-= H₂O+2e^-, while in acid solutions the electrochemical oxidation is direct: H₂=2H⁺+2e^-. In both cases electrolyte acidifying occurs because of the OH^- consumption or H⁺generation, making suitable the application of very acid electrolytes to avoid the sensor characteristics changes caused by a great pH changes over time.

 A 3-electrode probe similar to the Clark type oxygen probe construction was proposed, elaborated, and characterized as a dissolved hydrogen sensor. Its analytical characteristics such as LOD, sensitivity, response time, and linear response concentration range were determined as a function of the temperature, membranes materials, the electrolytes composition, and pH. Coulometric controlled electrochemical hydrogen generator was applied for standard solution preparation.

The sensor characterization results are presented and discussed together with the results obtained from its application for the real time determination of the rate of hydrogen production by the varieties B10 and IR3 of the photosynthetic strain Phodobacter Capsulatus.

 Acknowledgement. This work was supported by CONACyT Mexico: Research grant No. 152961, CONACYT-SENER “Sustentabilidad Energética” 2010-01.