In Situ Determination of Photobioproduction of H₂ by In₂S₃-[NiFeSe] Hydrogenase from Desulfovibrio vulgaris Hildenborough Using Only Visible Light

Abstract

An interesting strategy for photocatalytic production of hydrogen from water and sunlight is the formation of a hybrid photocatalyst that combines an inorganic semiconductor able to absorb in the visible light spectral range with an enzymatic catalyst for reducing protons. In this work we study how to optimize the interfacing of In 2 S 3 particles with the soluble form of [NiFeSe] hydrogenase from Desulfovibrio vulgaris Hildenborough by means of its initial H 2 photoproduction rate. The kinetics of the photocatalytic process was studied by membrane-inlet mass spectrometry, in order to optimize the interaction between both components of the hybrid photocatalyst. Membrane-inlet mass spectrometry allows measuring in the same experiment, for Page 1 of 35 ACS Paragon Plus Environment ACS Catalysis 2 comparison, the rate of H 2 production by the photocatalyst hybrid directly in the aqueous solution in real time and the result of a standard assay of the hydrogenase activity. An incubation period of 6 hours under mild stirring of hydrogenase with In 2 S 3 particles was necessary for optimal interaction of the enzyme molecules with the porous surface of the semiconductor. A turnover frequency of the NiFeSe Hydrogenase (TOF Hase) for H 2-photobioproduction of 986 s-1 was measured under the optimized conditions. This means that the immobilized hydrogenase has a photocatalytic efficiency for H 2 generation which is 94% of that obtained in the standard specific activity test of H 2 production using reduced methyl viologen as electron donor.

Laccase-Catalyzed Bioelectrochemical Oxidation of Water Assisted with Visible Light

“…62 The particles ranged from 50 nm to micron-size agglomerates as observed by SEM, had a 37.2 nm crystal domain size determined by XRD, a 2.1 eV band gap, a specific area of 40.6 ± 0.3 m 2 g, a total pore volume of 0.168 cm 3 g, and an average pore width of 16.5 nm. 62 Additional characterization was done after modification of the FTO electrodes with In 2 S 3 particles. A clean sample of FTO, a FTO-In 2 S 3 electrode, and a FTO-In 2 S 3 -ThLc electrode were visualized by SEM, Figure 2.…”

“…44,50 Although the overpotential shown by copper complexes is very promising, the use of an extra energy provided by the light may help to reduce the energy to invest in the process. The In 2 S 3 semiconductor is able to absorb visible light, and has shown ability to transfer the lightexcited electrons to a hydrogenase enzyme in presence of a sacrificial electron donor so that the enzyme reduces protons to H. 62 In 2 S 3 may be also coupled to electrodes to promote oxidative reactions, as the excited electrons can be swiftly transferred to the positively polarized electrode before recombination. 53 Hence, immobilizing the laccase on the surface of the In 2 S 3 modified electrode can take the advantage of the light energy to reduce the applied potential needed for H 2 O electrooxidation.…”

“…As derived from the results with filtered light it seems that not all the photons able to promote electrons to the conduction band generate holes with such a low energy to allow the O 2 evolution catalyzed by the laccase. Despite that the light absorption onset for In 2 S 3 is λ ≤ 600 nm, 62 it was needed to allow the photons with λ ≥ 400 nm to obtain a measurable O 2 production (Fig. S6).…”

Facile One‐Pot Solvothermal Synthesis of Noble Metal‐Free NiS Modified In2S3‐Based Photocatalyst for Highly Efficient Visible‐Light‐Driven Cr6+ Removal

“…In 2 S 3 was a kind of semiconductor widely used for the photocatalytic field for its proper bandgap alignment, easily accessible method, and high efficiency [34–40] . It has a 2.0– 2.2 eV bandgap enabling the longer wavelength light can be absorbed [36,41–47] . The negative enough conduction band position was proved to be −0.79 eV which is strong enough and enables most kinds of reductive reaction happening.…”

Underpotential Photoelectrooxidation of Water by SnS2−Laccase Co‐catalysts on Nanostructured Electrodes with Only Visible‐Light Irradiation

“…More recently, biological catalysts have also been tested in photocatalytic studies. Hydrogenases have been linked to different semiconductors, such as TiO 2 , CdS, or In 2 S 3 , to facilitate H 2 synthesis, although the combination of enzymes and semiconductors for the water oxidation reaction remains underdeveloped. This may be attributed to the difficulty of producing O 2 from H 2 O and the lack of efficient biocatalysts.…”