Light-Driven Hydrogen Production by Hydrogenases and a Ru-Complex inside a Nanoporous Glass Plate under Aerobic External Conditions

Abstract

Hydrogenases are powerful catalysts for light-driven H2 production using a combination of photosensitizers. However, except oxygen-tolerant hydrogenases, they are immediately deactivated under aerobic conditions. We report a light-driven H2 evolution system that works stably even under aerobic conditions. A [NiFe]-hydrogenase from Desulfovibrio vulgaris Miyazaki F was immobilized inside nanoporous glass plates (PGPs) with a pore diameter of 50 nm together with a ruthenium complex and methyl viologen as a photosensitizer and an electron mediator, respectively. After immersion of PGP into the medium containing the catalytic components, an anaerobic environment automatically established inside the nanopores even under aerobic external conditions upon irradiation with solar-simulated light; this system constantly evolved H2 with an efficiency of 3.7 μmol H2 m(-2) s(-1). The PGP system proposed in this work represents a promising first step toward the development of an O2-tolerant solar energy conversion system.

A Redox Hydrogel Protects the O2‐Sensitive [FeFe]‐Hydrogenase from Chlamydomonas reinhardtii from Oxidative Damage

“…[5b,15, 23] Them ain strategies to improve their O 2 tolerance to date relied either on the design of specific mutant proteins, [24] or on the generation and screening of large random mutagenesis libraries, [25] both up to now with rather limited success.These results show how our chemical approach of using aviologenmodified hydrogel effectively protects an extremely O 2sensitive hydrogenase to such an extent that its utilization in afuel cell with amixed H 2 /O 2 gas feed becomes possible.The fuel cell performance was comparable to that of earlier reported non-nanostructured fuel cells based on O 2 -tolerant hydrogenases. [27] Future development of the redox hydrogel will focus on increasing the kinetics for O 2 reduction to water [8,28] to prevent the partially reduced reaction intermediates such as superoxide and hydrogen peroxide from degrading the viologen [29] and possibly the enzyme upon extended exposure. Thee nzyme remains active at O 2 levels as high as 5% in H 2 which is far above the level of O 2 impurities present in the gas feeds typically used in technological applications.T his opens up new possibilities to exploit extremely active but highly O 2sensitive and irreversibly deactivated catalysts in fuel cells and in photocatalytic H 2 -evolving systems.…”

Ru(II)-diimine functionalized metalloproteins: From electron transfer studies to light-driven biocatalysis

“…[63] More recently, entrapping the hydrogenase into a nanoporous glass plate in the presence of Ru(bpy) 3 2+ and methyl viologen has resulted in the production of hydrogen with an efficiency of 3.7 μmol H 2 m −2 s −1 under external aerobic conditions. [64]…”

Oxygen-tolerant proton reduction catalysis: much O2 about nothing?

“…63 In this case, a nanoporous glass plate was soaked in a tris(bipyridine)ruthenium II dye, MV and a [NiFe] hydrogenase from Desulfovibrio vulgaris. 63 In this case, a nanoporous glass plate was soaked in a tris(bipyridine)ruthenium II dye, MV and a [NiFe] hydrogenase from Desulfovibrio vulgaris.…”

“…(a). Reduced methyl viologen is generated upon photo--excitation of the dye and used to reduce the hydrogenase and quench O2 inside the pores to produce an anaerobic environment 63. (b) O2--shielding strategy based on a multi--component system consisting of a Ru dye, methyl viologen as soluble redox mediator and a hydrogenase in nanoporous glass.…”