title: Mechanism of pH-switchable peroxidase and catalase-like activities of gold, silver, platinum and palladium.
abstract: Despite being increasingly used as artificial enzymes, little has been known for the origin of the pH-switchable peroxidase-like and catalase-like activities of metals. Using calculations and experiments, we report the mechanisms for both activities and their pH-switchability for metals Au, Ag, Pd and Pt. The calculations suggest that both activities are intrinsic properties of metals, regardless of the surfaces and intersections of facets exposed to environments. The pre-adsorbed OH groups on the surfaces, which are only favorably formed in basic conditions, trigger the switch between both activities and render the pH-switchability. The adsorption energies between H2O2 and metals can be used as convenient descriptors to predict the relative enzyme-like activities of the metals with similar surface morphologies. The results agree with the enzyme-mimic activities that have been experimentally reported for Au, Ag, Pt and predict that Pd should have the similar properties. The prediction, as well as the predicted activity order for the four metals, has been verified by the experimental tests. The results thus provide an in-depth insight into the peroxidase-like and catalase-like activities of the metals and will guide the de novo design, synthesis and application of artificial enzymes based on inorganic materials.
authors.affiliation: CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Junnan
authors.initials: J
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology of China, Beijing 100190, China.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Liu
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology of China, Beijing 100190, China. Electronic address: wuxc@nanoctr.cn.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wu
authors.affiliation: CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. Electronic address: gaox@ihep.ac.cn.
authors.forename: Xingfa
authors.initials: X
authors.lastname: Gao
mesh_terms: D000327:Adsorption; D002374:Catalase / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010165:Palladium / Q000737:chemistry*; D009195:Peroxidase / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D012834:Silver; D010984:Platinum; D010165:Palladium; D006046:Gold; D006861:Hydrogen Peroxide; D002374:Catalase; D009195:Peroxidase
keywords: Catalysts; Density-functional calc.; Metals; Reaction mechanisms; Surface