Biosynthetic CdS-Thiobacillus thioparus hybrid for solar-driven carbon dioxide fixation

Synergistically combining biological whole-cell bacteria with man-made semiconductor materials innovates the way for sustainable solar-driven CO2 fixation, showing great promise to break through the bottleneck in traditional chemical photocatalyst systems. However, most of the biohybrids require uneconomical organic nutrients and anaerobic conditions for the successful cultivation of the bacteria to sustain the CO2 fixation, which severely limits their economic viability and applicability for practical application. Herein, we present an inorganic-biological hybrid system composed of obligate autotrophic bacteria Thiobacillus thioparus (T. thioparus) and CdS nanoparticles (NPs) biologically precipitated on the bacterial surface, which can achieve efficient CO2 fixation based entirely on cost-effective inorganic salts and without the restriction of anaerobic conditions. The optimized interface between CdS NPs and T. thioparus formed by biological precipitation plays an essential role for T. thioparus efficiently receiving photogenerated electrons from CdS NPs and thus changing the autotrophic way from chemoautotroph to photoautotroph. As a result, the CdS-T. thioparus biohybrid realizes the solar-driven CO2 fixation to produce multi-carbon glutamate synthase and biomass under visible-light irradiation with CO2 as the only carbon source. This work provides significant inspiration for the further exploration of the solar-driven self-replicating biocatalytic system to achieve CO2 fixation and conversion.