Ensemble of single-atom catalysis and defect engineering in Cu 1 /CeO 2 nanozymes for tumor therapy

As a class of nanomaterials with natural enzyme-like characteristics, nanozymes have shown their great potential in various applications. Reducible metal oxides featured with defect structures, and single-atom catalysts with isolated metal sites are regarded as two of the most promising nanozymes. However, the strategies to construct highly performed nanozymes by combining these advantages are rarely reported. Herein, we report the coordination-unsaturated single-atomic Cu species supported on sintered CeO 2 , which combines the advantages of defect engineering and single-atom catalysis, exhibiting a largely enhanced peroxidase (POD)-like activity. The high-temperature calcination induces the transformation of inert Cu 1 O 4 species into coordination-unsaturated Cu 1 O 3 sites. This novel Cu 1 O 3 active sites with an unsaturated coordination work as a new type of defect sites to greatly activate the isolated Cu atoms and accelerate the dissociation of H 2 O 2 to form hydroxyl radicals (·OH). The obtained nanozyme with a high POD-like activity possesses low cytotoxicity, showing potential applications for the tumor inhibition in vitro and in vivo .