Facile Functionalization of Carbon Electrodes for Efficient Electroenzymatic Hydrogen Production

Abstract

Enzymatic electrocatalysis holds promise for new biotechnological approaches to produce chemical commodities such as molecular hydrogen (H2). However, typical inhibitory limitations include low stability and/or low electrocatalytic currents (low product yields). Here we report a facile single-step electrode preparation procedure using indium–tin oxide nanoparticles on carbon electrodes. The subsequent immobilization of a model [FeFe]-hydrogenase from Clostridium pasteurianum (“CpI”) on the functionalized carbon electrode permits comparatively large quantities of H2 to be produced in a stable manner. Specifically, we observe current densities of >8 mA/cm2 at −0.8 V vs the standard hydrogen electrode (SHE) by direct electron transfer (DET) from cyclic voltammetry, with an onset potential for H2 production close to its standard potential at pH 7 (approximately −0.4 V vs. SHE). Importantly, hydrogenase-modified electrodes show high stability retaining ∼92% of their electrocatalytic current after 120 h of continuous potentiostatic H2 production at −0.6 V vs. SHE; gas chromatography confirmed ∼100% Faradaic efficiency. As the bioelectrode preparation method balances simplicity, performance, and stability, it paves the way for DET on other electroenzymatic reactions as well as semiartificial photosynthesis.

Electrostatic [FeFe]-hydrogenase–carbon nitride assemblies for efficient solar hydrogen production

“…† [FeFe]-H 2 ase from Clostridium pasteurianum (CpI, heterologously produced in Escherichia coli) and [NiFeSe]-H 2 ase from Desulfovibrio vulgaris Hildenborough (DvH) were expressed and puried under anaerobic conditions. 20,21 Fig. 1 illustrates the hypothesis that the negatively charged NCN CN X possesses the ability to activate enzymes with positively charged electron entry points, such as CpI [FeFe]-H 2 ase.…”

“…[FeFe]-H 2 ase from Clostridium pasteurianum ( CpI , heterologously produced in Escherichia coli ) and [NiFeSe]-H 2 ase from Desulfovibrio vulgaris Hildenborough ( Dv H) were expressed and purified under anaerobic conditions. 20,21…”