Surface Cleaning And Protection Engineering To Awaken The Intrinsic Catalytic Activity Of CO₃O₄

The hydroxyl groups on the surface of transition metal oxide catalysts are typical destructive poison which limit the intrinsic catalytic performance.The hydroxyl groups on the catalyst surface derive from the adsorption and dissociation of water molecules.Both the hydroxylation of surface cations and the hydrogenation of lattice oxygen would poison and inactivate the catalysts.Therefore,the removal of surface hydroxyl groups and the protection of the surface active site are benefit for maximize the intrinsic catalytic performance of transition metal oxide catalysts.In previous studies,the reduction of hydroxyl accumulation on the surface is usually achieved by the introduction of additional elements.However,the screening of additional elements and the optimization of their concentration usually require tedious repeated trials and error experiments.The determination of the candidate collection for the additional elements and the innovation of the catalyst modification strategy could effectively shorten the development cycle and cost of new materials and conserve a great amount of human and material resources.Firstly,the water poisoning mechanism on a series of transition metal oxides surfaces was systematically investigated by the first-principles calculations.It was found that the hydrogen bond induction between adsorbed water molecules and surface lattice oxygen promoted the dissociation of water molecules,and the adsorption and dissociation of water molecules gradually increased the difficulty of oxygen vacancy regeneration and reduced the cycle life of oxygen vacancy.Even more deadly,the hydroxyl groups formed by the decomposition of water molecules wait for the opportunity to occupy the newly created oxygen vacancy and destroy the active site,resulting in severe poisoning deactivation of the catalyst.Secondly,methanol molecules were successfully assembled on the Co₃O₄surface by using surface functionalization technology.The assembled methanol molecules effectively removed the surface hydroxyl groups and preventing the surface from water eroding.The first-principles calculation showed that the removal of the surface hydroxyl groups by methanol molecules was spontaneous,the assembled methanol recovered the original chemical properties of purified Co₃O₄ and awakened its intrinsic catalytic activity of.The molecular dynamics simulation and experimental characterization showed that methanol clusters accumulated in Co₃O₄ pores and formed new hydrophobic entrance,which effectively prevented water molecules from entering the pore and protected the internal surface of Co₃O₄.Finally,this work studied the doping sites of transition metal elements in Co₃O₄surface,and the oxygen vacancy formation sites,CO adsorption sites and H₂O adsorption sites on the element-doped surface by using high-throughput calculations.The databases for adsorption energy of molecules on the doped surface were created.,and the candidate elements which could promote oxygen vacancy formation,enhance CO adsorption and weaken H₂O adsorption were screened out.Furthermore,the methanol adsorption strength on element-doping Co3O4 was reasonably predicted by using machine learning,and the map from the simplest physicochemical properties of doping elements and adsorbed molecules to the adsorption capacity was successfully constructed,which provide the possibility for the surface controllable functionalization of Co₃O₄.This work integrated multidisciplinary research methods,deeply explored the mechanism of water poisoning on the surface of transition metal oxides,innovatively introduced surface functionalization technology into the CO catalytic oxidation,systematically studied the influence of element doping on the Co₃O₄ properties,and provided candidate collections of elements for Co₃O₄surface controllable functionalization.This work has established the atomic and electronic scale description for H₂O poisoning mechanism,modifications and catalytic reactions,constructed databases of many important properties of element-doping Co₃O₄.This work provides a profound understanding for the removal of surface poisons and the awakening of the intrinsic activity of transition metal oxide catalysts.This work provides a theoretical guidance for the research and development of transition metal oxide catalysts with high catalytic performance,water resistance and durability.