From two-component enzyme complex to nanobiohybrid for energy-efficient water-gas shift reaction

The water-gas shift reaction (WGSR, CO + H₂O ⇔ CO₂ + H₂) is widely used for the upgrading of syngas, a key substrate for various chemical processes. However, the industrial WGSR requires high pressure and temperature, and has low selectivity. Here, we have designed a biohybrid catalyst by combining CODH from Rhodospirillum rubrum, which catalyzes CO-to-CO₂ conversion and a bioinspired nickel bisdiphosphine complex, which catalyzes the hydrogen evolution reaction, immobilized on carbon nanotubes. Carbon nanotubes enable the dual functioning of both catalysts providing efficient electrical conductivity and allowing electroless CO-to-CO₂ conversion and H₂ evolution. Owing to CO tolerance of the Ni complex, this bioinspired nanohybrid catalyst shows high performance by reaching 100% conversion yield and maximum TOF of 30 s^-1 towards WGSR at ambient temperature and pressure in the presence of either pure CO or syngas.