Semi-artificial photosynthesis merges synthetic and biological approaches to produce sustainable fuels using sunlight, particularly excelling in selective multicarbon product formation via biocatalysis. A hybrid solar water splitting-biosynthetic system has been reported, where intermediate green H₂ is used as a reductant to fix CO₂ and efficiently produce biomass and fuels using Cupriavidus necator. Coupling a synthetic photocatalyst with Shewanella oneidensis resulted in selective hydrogenation of C=C and C=O bonds. The photosensitization of Moorella thermoacetica with extracellular CdS or intracellular gold nanoclusters established a novel pathway for photocatalytic CO₂ utilization, integrating microbial systems with nanomaterials to enhance photosynthetic efficiency. Gas fermenting acetogenic bacteria, particularly Clostridium species, have emerged as versatile platforms for producing biofuels and biochemicals from syngas, a mixture of H₂, CO and CO2. These Clostridium strains utilize the Wood-Ljungdahl pathway, which consists of two branches (Figure ) to produce the C2 compounds: the methyl branch, reducing CO₂ to formate and further to a methyl group, and the carbonyl branch, which forms an acetyl group from CO. Clostridium ljungdahlii (Cl) has shown promise in fermenting these gases into valuable products, underscoring the economic viability of this approach in biotechnology. For instance, a carbon-negative fermentation process using engineered and closely related Clostridium autoethanogenum to convert waste gas feedstocks into acetone and isopropanol with high efficiency. A Ag-catalyst based gas diffusion electrolyzer for CO₂to-syngas conversion was coupled with syngas-fermenting C. autoethanogenum and C. kluyveri, producing butanol and hexanol with high selectivity and therefore offers a sustainable pathway for industrial chemical production from CO₂ and water using renewable energy. To further harness and optimize the metabolic capabilities of these microorganisms, adaptive laboratory evolution (ALE) emerges as a powerful tool to select and enhance beneficial traits without the need for genetic engineering.