A comparative study on carbon neutral hydrogen carrier production: Formic acid from CO₂ vs. ammonia

Hydrogen (H 2 ) is increasingly recognized as a key player in the journey towards carbon neutrality, with ammonia (NH 3 ) and formic acid (FA) emerging as significant hydrogen vectors. This review highlights advancements in catalyst efficiency for FA synthesis from CO 2 , particularly with bismuth (Bi) and tin (Sn) catalysts. It investigates diverse NH 3 and FA production methodologies, such as electrochemical, thermochemical, and photochemical processes, and underscores the integration of renewables to address their energy demands. The study also reviews novel materials like metal-organic frameworks (MOFs) and carbon-based catalysts that could enhance catalytic effectiveness. Transitioning from lab-scale models to industrial-scale applications requires addressing catalyst longevity and process enhancement, and it suggests investigating hybrid systems that might offer improved efficiency and yields. Concluding with a directive for future research, the study advocates for scalable, economically viable, and environmentally sustainable CO 2 conversion technologies, underscoring the essential roles of NH 3 and FA in a future with reduced carbon emissions.