Sustainable Inorganic Chemistry: Metal Separations for Recycling.

Inorganic materials are critical components of clean energy technology. For example, rare earths are key for the function of electric car batteries and in permanent magnets used in wind turbines, and palladium helps to reduce harmful exhaust in automotive three-way catalysts. Many of the critical elements for these materials are of low abundance in the earth's crust, found in few places globally, and/or require energy- and resource-intensive purification. By comparison, many of these elements are concentrated in waste electrical and electronic equipment, which represents an attractive secondary resource. Inorganic chemists are ideally positioned to develop new chemistry and greener processes that are more efficient and use less hazardous reagents to separate high-value metals from waste electronics. The purpose of this Viewpoint is to highlight recent discoveries in fundamental inorganic chemistry that can contribute to new recycling technologies for gold, lithium, palladium, germanium, and rare earths, especially using simple approaches in solid-liquid extraction. Such fundamental studies are expected to help close metal supply chain loops and create circular economies.