Advancements and Challenges in Catalytic Nitrogen-to-Ammonia Conversion: Insights into Electrocatalysis, Photocatalysis, and Biocatalysis

High Resolution Image Download MS PowerPoint Slide Ammonia (NH 3 ) is vital for modern agriculture and is a potential carbon-free energy carrier. However, its current synthesis via the Haber-Bosch process is energy-intensive, consuming ∼2% of global energy and emitting over 500 Mt of CO 2 annually. To address the growing demands for sustainable nitrogen fixation, alternative ammonia synthesis methods under ambient conditions have gained attention. Electrochemical (ENRR), photochemical (PNRR), and biocatalytic (BNRR) nitrogen reduction reactions (NRRs) offer promising approaches. ENRR uses renewable electricity but faces low Faradaic efficiency and competition from hydrogen evolution. PNRR utilizes solar energy but suffers from poor selectivity and low quantum yields. BNRR mimics nitrogenase enzymes with high selectivity but struggles with ATP dependency and scalability. Advances in catalyst design, single-atom engineering, and isotopic validation have improved these strategies, yet challenges remain. This review explores progress, mechanisms, and future directions for sustainable ammonia production.