Figure 6. The concept of coupled enzyme redox catalysis on electronically conductive graphite platelet particles.

(A) Schematic representation of hydrogenase and nitrate reductase co-immobilised on graphite particles. (B) Results from a Griess reagent assay showing that H₂-driven reduction of nitrate to nitrite by enzyme-modified particles (NHG) occurs only when nitrate reductase (N) and hydrogenase (H) are co-adsorbed on the graphite particles (G), but not in the absence (−) of any of these components. Panel (B) is reproduced from work by Vincent et al. with permission from ref. [42]. (C) Schematic representation of hydrogenase and carbon monoxide dehydrogenase co-immobilised on carbon particles for catalysis of the water-gas shift reaction.