Abstract
A peroxidase catalyzes the oxidation of a substrate with a peroxide. The search for peroxidase-like and other enzyme-like nanomaterials (called nanozymes) mainly relies on trial-and-error strategies, due to the lack of predictive descriptors. To fill this gap, here we investigate the occupancy of eg orbitals as a possible descriptor for the peroxidase-like activity of transition metal oxide (including perovskite oxide) nanozymes. Both experimental measurements and density functional theory calculations reveal a volcano relationship between the eg occupancy and nanozymes’ activity, with the highest peroxidase-like activities corresponding to eg occupancies of ~1.2. LaNiO3-δ, optimized based on the eg occupancy, exhibits an activity one to two orders of magnitude higher than that of other representative peroxidase-like nanozymes. This study shows that the eg occupancy is a predictive descriptor to guide the design of peroxidase-like nanozymes; in addition, it provides detailed insight into the catalytic mechanism of peroxidase-like nanozymes.
Highlights
Artificial enzymes aim to imitate the unique catalytic activities of natural enzymes using alternative materials
The as-prepared perovskites were fully characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), powder X-ray diffraction (PXRD), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and Brunauer–Emmett–Teller (BET) surface area measurements
To identify a suitable descriptor for the peroxidase-like activity of perovskite transition metal oxides (TMOs), we initially examined La1-xSrxFeO3-δ compositions (x = 0–1), because the eg occupancy of Fe in this series of perovskites could be gradually tuned by substituting La3+ with Sr2+ cation (Fig. 1b and Supplementary Table 4)
Summary
Artificial enzymes aim to imitate the unique catalytic activities of natural enzymes using alternative materials. Functional nanomaterials with enzyme-like catalytic activities, called nanozymes, have emerged as promising alternatives that could overcome the low stability and high cost of natural enzymes[1,2,3,4,5,6,7,8,9,10,11,12,13]. We have recently developed Ni oxide-based peroxidase mimics for glucose detection in serum[20]. These peroxidase-like nanozymes are generally developed using trial-and-error strategies[14]. Structural characteristics of the nanomaterials that can be used as proxies for their peroxidase-like activities This lack of predictive descriptors significantly hampers the identification of more active nanozymes
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