Method to Turn CO2 Into Plastic With High Efficiency
"Researchers have developed catalysts that can convert carbon dioxide into plastics, fabrics, resins, and other products. The electrocatalysts are the first materials, aside from enzymes, that can turn carbon dioxide and water into carbon building blocks containing one, two, three, or four carbon atoms with more than 99 percent efficiency."
Two of the products—methylglyoxal (C3) and 2,3-furandiol (C4)—can be used as precursors for plastics, adhesives, and pharmaceuticals. Toxic formaldehyde could be replaced by methylglyoxal, which is safer.
We introduce five nickel phosphide compounds as electro-catalysts for the reduction of carbon dioxide in aqueous solution, that achieve unprecedented selectivity to C3 and C4 products (the first such report). Three products: formic acid (C1), methylglyoxal (C3), and 2,3-furandiol (C4), are observed at potentials as low as +50 mV vs. RHE, and at the highest half-reaction energy efficiencies reported to date for any >C1 product (99%). The maximum selectivity for 2,3-furandiol is 71% (faradaic efficiency) at 0.00 V vs. RHE on Ni2P, which is equivalent to an overpotential of 10 mV, with the balance forming methylglyoxal, the proposed reaction intermediate. P content in the series correlates closely with both the total C products and product selectivity, establishing definitive structure–function relationships. We propose a reaction mechanism for the formation of multi-carbon products, involving hydride transfer as the potential-determining step to oxygen-bound intermediates. This unlocks a new and more energy-efficient reduction route that has only been previously observed in nickel-based enzymes. This performance contrasts with simple metallic catalysts that have poor selectivity between multi-carbon products, and which require high overpotentials (>700 mV) to achieve comparable reaction rates.