Sunlight-driven catalytic urea synthesis offers a sustainable ambient-pressure pathway for fertilizer production, but energy-intensive liquid-urea separation limits its practicality. Non-aqueous photothermal urea synthesis from gaseous NH3 and CO2 offers a promising alternative, though molecular activations under dry and mild conditions remain challenging. Here, we report photothermal urea synthesis over Ru nanocrystals supported on acidic Al2O3, basic MgO, and neutral SiO2, achieving an optimal rate of 2745.71 ± 46.91 µmolurea gRu -1 h-1, an order-of-magnitude higher than state-of-the-arts at ambient pressure. Mechanistic studies elucidate a reaction pathway, initiated photothermally by Ru and orchestrated by an acidic chemical environment that promoted the availability of reactants, in which exothermic N-H bond dissociation of NH3 matches endothermic C-N coupling with CO2 in a thermodynamically favorable manner. This work demonstrates an ultra-efficient pioneering synthesis paradigm under near-ambient conditions, circumventing industrial reliance on harsh thermochemical conditions.
Zhao et al. (Mon,) studied this question.