Bio‐Photocatalytic Synergy Enables Valorization of CH ₄ and CO ₂ Into Hydrogen and 4‐Hydroxybenzoate in Engineered Methanotrophic Bacteria

Valorization of decentralized one‐carbon chain (C 1 ) resources into value‐added products has garnered significant attention, owing to its dual benefits in resource recovery and carbon mitigation. To address the challenge of co‐converting methane (CH 4 ) and carbon dioxide (CO 2 ), we developed a solar‐driven biohybrid system that synergistically integrates biosynthesis and photocatalysis. The core of this system relies on a genetically engineered methanotrophic cell factory and newly designed biocompatible photocatalytic metal complexes. The methanotrophic bacteria utilize CH 4 as the primary feedstock to biosynthesize 4‐hydroxybenzoate (4HBA) while realizing CO 2 sequestration. The photocatalytic metal complexes, meanwhile, capture formate (a metabolic byproduct of cells) to generate hydrogen (H 2 ) and photoelectrons—with the latter directly supplying reducing power to support cellular activities in genetically tailored cells. Under optimal conditions, this solar‐driven system achieved a 4HBA titer of 472.36 µg/L, a H 2 yield of 0.59 mmol H 2 /mol CH 4 , and over 50% reduction in carbon emissions. The study not only establishes a feasible biomanufacturing strategy for the upcycling of C 1 gaseous feedstocks but also highlights the potential of integrating biological and photochemical technologies to advance sustainable energy and environmental solutions.