The history of metal catalysis was that often some of the most toxic and/or precious metals were developed and used as catalysts and targeted for research and study. These include osmium, mercury, chromium, platinum, palladium, gold, iridium and others. The cost and sustainability impacts of this approach are significant. While it must be noted that there exist excellent recovery schemes, each of these have costs and risks that should be minimized.

The exploitation of Earth-abundant metals (e.g., iron, copper) that are not scarce nor depleting is an active area of development that will be important to achieve the necessary advantages of metal catalysis without the same associated historic impacts.