Advances in Hydrogen-Driven Bicarbonate Conversion to Formic Acid and Formate Salts.

According to a January 2025 report by the UK Met Office, carbon dioxide (CO) levels are expected to reach 429.6 ppm in May, marking the highest concentration in over 2 million years. This alarming rise has intensified global efforts to mitigate climate change through carbon capture and utilization (CCU) technologies. A promising strategy is converting CO into valuable chemicals such as formic acid and formate salts. Formic acid, in particular, is seen as a potential hydrogen carrier, addressing challenges in hydrogen storage and transport. However, the direct hydrogenation of CO to formic acid is thermodynamically challenging due to the high stability. To overcome these barriers, researchers have explored alternative pathways, such as the reduction of bicarbonate (HCO ), which is more reactive and easier to handle. Bicarbonate can be sourced from CO-rich streams like flue gases or seawater, simplifying capture and conversion. This review explores hydrogen-driven bicarbonate conversion via catalytic methods: electrocatalysis, thermocatalysis, photocatalysis, homogeneous, and enzymatic catalysis. Each uses distinct energy inputs and offers unique advantages. While electrocatalysis shows 90% Faradaic efficiency, photocatalysis and enzymatic approaches remain limited by quantum yields and scalability. The review outlines key advances, challenges, and future directions to enhance these technologies for a sustainable, carbon-neutral future.