Room-temperature and carbon-negative production of biodiesel via synergy of geminal-atom and photothermal catalysis

Catalytic biodiesel production with bases can be achieved under relatively mild conditions. However, the basicity of solid alkali catalysts originates usually from electron-rich atoms such as oxygen and nitrogen, rather than electron-deficient metal species. This typically induces aggregation and leaching of active sites, and difficulty in recycling. Here we synthesized a photothermal catalyst made of stable and uniformly dispersed graphene-like biomaterial anchored neighboring potassium single atoms. The production of biodiesel from various acidic oils over this catalyst was evaluated by life cycle assessment and cost analysis. Infrared thermal imaging and finite element simulations were used to study the light-induced self-heating process. We further studied the alkaline behavior of neighboring potassium single atoms by carbon dioxide chemisorption and quantum calculations. Results show biodiesel yield of 99.6% at room temperature, which is explained by a good local photothermal effect at the solar interface and the presence of superalkali sites in the atomic potassium-containing biomaterial. The global warming potential measured for this system resulted in a net negative CO₂ emission of −10.8 kg CO₂eq/kg. The photothermal catalyst can be recycled with almost no decline in reactivity.