Metal‐Free Semiconductor‐Based Bio‐Nano Hybrids for Sustainable CO2‐to‐CH4Conversion with High Quantum Yield

Abstract Bio‐nano hybrids with methanogens and nano‐semiconductors provide an innovative strategy for solar‐driven CO 2 ‐to‐CH 4 conversion; however, the efficiency mismatch between electron production and utilisation results in low quantum yield and CH 4 selectivity. Herein, we report the integration of metal‐free polymeric carbon nitrides (CN x ) decorated with cyanamide (NCN) groups and Methanosarcina barkeri ( M. b ). The self‐assembled M. b ‐ NCN CN x exhibited a quantum yield of 50.3 % with 92.3 % CH 4 selectivity under illumination, which outperforms other reported bio‐nano hybrid systems and photocatalytic systems for CO 2 reduction. This excellent performance was attributed to the distinct capacitance and conductive effects of NCN CN x , which promoted electron storage and redistribution at the biotic–abiotic interface to alleviate recombination losses and side reaction. This study provides new design guidelines for bio‐nano hybrids for the sustainable photocatalytic reduction of CO 2 into fuels.