Photothermal Catalysis Enables Sustainable Ammonia Production over Cs-Promoted Fe-Based Catalyst Supported on Carbon

Photothermal catalysis, an approach that harnesses both thermal and nonthermal contributions of sunlight, has emerged as a promising strategy to drive chemical transformations with enhanced efficiency and reduced energy requirements. In this study, we report a Cs-promoted Fe-based catalyst derived from the pyrolysis of Fe phthalocyanine precursor for photothermal ammonia (NH 3 ) synthesis. Among the studied catalysts, those pyrolyzed at 600 °C displayed the highest performance, with an average NH 3 production rate of 26 mmol g Fe –1 h –1 at 400 °C and 20 bar under light irradiation. In addition, the catalyst displayed remarkable stability for over 50 h on stream. Mechanistic studies revealed a predominant contribution from nonthermal effects, particularly at higher light intensities (>3.5 W cm –2 ), indicating that charge carrier-mediated contributions dominate the reaction pathway. Overall, this work presents Fe-based photothermal catalysts as a sustainable approach for efficient solar-driven NH 3 production.