Sunlight-to-Chemicals: A Robust Biohybrid System for Formic Acid Production | Motiar Rahaman

Fuel-forming enzymes exhibit excellent performance, achieving high catalytic rates with remarkable selectivity at very low overpotentials during electrocatalytic processes. However, they are typically considered to be fragile and challenging to integrate with synthetic semiconductors for sunlight-driven chemical synthesis. Here, we present a biohybrid platform constructed from cyanamide-functionalized carbon nitride (CNX) as a cost-effective and scalable photosensitizer that selectively photo-oxidizes 4-methyl benzyl alcohol (MBA) to 4-methyl benzaldehyde (MBAld), indium tin oxide (ITO) nanoparticles as an electron conduit and biocatalyst (enzyme) support, and the enzyme formate dehydrogenase (FDH) for selective CO₂-to-formate conversion. This integrated semiartificial multicomponent system can be configured in various ways for bias-free operation, including (i) a photocatalytic suspension, (ii) a photocatalyst sheet, and (iii) a photoelectrochemical cell. The excellent adaptability and durability of these biohybrid systems led us to select the most efficient and scalable configuration for practical solar chemical production under outdoor conditions. This work establishes CNX-ITO|FDH as a robust, versatile, and scalable semiartificial platform for extended solar-driven chemical synthesis under real-world conditions.

Keywords: Power-to-Chemical, Solar-driven Chemistry, Enzyme-based Biohybrids, Sustainability

This presentation is part of the Power-to-X for a Sustainable Future Workshop 2025, taking place on 14–16 September 2025 at the Montien Hotel Surawong, Bangkok, Thailand. The Power-to-X initiative is supported by the Royal Academy of Engineering.