Water Splitting–Biosynthetic Hybrid System for CO2 Conversion using Nickel Nanoparticles Embedded in N-Doped Carbon Nanotubes

Graphical Confining metal inside carbon : Ni nanoparticles are embedded into N-doped carbon nanotubes (Ni@N-C) by rational catalyst design. The Ni@N-C catalyst exhibits high catalytic activity and good biocompatibility, which is further coupled with Cupriavidus necator H16 in a water splitting–biosynthetic system to achieve efficient conversion of CO 2 to poly-β-hydroxybutyrate. CO 2 reduction has drawn increasing attention owing to the concern of global warming. Water splitting–biosynthetic hybrid systems are novel and efficient approaches for CO 2 conversion. Intimate coupling of electrocatalysts and biosynthesis requires the catalysts possess both high catalytic performance and excellent biocompatibility, which is a bottleneck of developing such catalysts. Here, a complex of Ni nanoparticles embedded in N-doped carbon nanotubes (Ni@N-C) is synthesized as a hydrogen evolution reaction electrocatalyst and is coupled with a hydrogen oxidizing autotroph, Cupriavidus necator H16, to convert CO 2 to poly-β-hydroxybutyrate. In Ni@N-C, the Ni nanoparticles are encapsulated in N-C nanotubes, which prevents bacteria from direct contact with Ni and inhibits Ni 2+ leaching. As a result, Ni@N-C exhibits excellent biocompatibility and stability. This work demonstrates that electrocatalysts and biosynthesis can be intimately coupled through rational catalyst design.