Polythiophene-Based Nonmetal Electrocatalyst with Biocompatibility to Boost Efficient CO2 Conversion

In a hybrid microbial–inorganic catalysis system, H₂ evolution reaction (HER) electrocatalysts are coupled with microorganisms to achieve the highly efficient conversion of CO₂ to value-added chemicals using H₂ as an electron mediator. However, currently developed HER electrocatalysts suffer from poor biocompatibility, hindering the performance of the system. This study presents a N- and Si-doped polythiophene nanocomposite (PTh-NSi) as a nonmetal HER electrocatalyst with biocompatibility for use in a hybrid microbial–inorganic catalysis system. By coupling PTh-NSi with Ralstonia eutropha H16, conversion of CO₂ to poly-β-hydroxybutyrate with a maximum yield of 662.99 ± 27.46 mg/L was achieved. The PTh-NSi electrocatalyst demonstrated HER performance in bacterial media, minimal reactive oxygen species production, and no heavy metal ion leaching, ensuring biocompatibility with R. eutropha H16. The interactions between PTh-NSi and R. eutropha H16 were revealed. This work highlights an approach to designing biocompatible catalysts for hybrid microbial–inorganic catalysis systems, offering the potential for sustainable CO₂ conversion.