The present disclosure relates to a substrate comprising nanoparticle catalysts and NOx storage materials for treatment of gases, and washcoats for use in preparing such a substrate. Also provided are methods of preparation of the nanoparticle catalysts and NOx storage materials, as well as methods of preparation of the substrate comprising the nanoparticle catalysts and NOx storage materials. More specifically, the present disclosure relates to a coated substrate comprising nanoparticle catalysts and NOx storage materials for lean NOx trap (LNT) systems, useful in the treatment of exhaust gases.