Oxide-Perovskites\nfor Automotive Catalysts Biotransform\nand Induce Multicomponent Clearance and Hazard

Oxide-perovskites designed for automotive catalysts contain\nmultiple\nmetal elements whose presence is crucial to achieving the targeted\nperformance. They are highly stable in exhaust operating conditions;\nhowever, little is known about their stability under physiological\nconditions. As some of the metallic components are hazardous to humans\nand the environment, perovskite benefits in cleaner air must be balanced\nwith risks in a Safe and Sustainable Design (SSbD) approach. New approach\nmethodologies (NAMs), including in chemico and in silico methods,\nwere used for testing hazards and benefits, including catalytic activity\nand tolerance for temporary excess of oxygen under dynamic driving\nconditions. The composition and surface properties of six different\nlanthanum-based oxide-perovskites compromised their stability under\nlung physiological conditions, influencing the oxidative damage of\nthe particles and the bioacessibility of leaching metals. We found\nconsistent biotransformation of the oxide-perovskite materials at\npH 4.5. The leached lanthanum ions, but not other metals, respeciated\ninto lanthanum phosphate nanoparticles, which increased the overall\noxidative damage in additive synergy. The NAM results in the presented\nSSbD approach were challenged by in vivo studies in rats and mice,\nwhich confirmed multicomponent clearance from lungs into urine and\nsupported the comparative ranking of effects against well-characterized\nspinel materials. Among the perovskites, the version with reduced\nnickel content and doped with palladium offered the best SSbD balance,\ndespite not improving the conventional benchmark catalytic performance\nand related sustainability benefits. Redesign by industry may be necessary\nto better fulfill all SSbD dimensions.