Effects of 8-mer acidic peptide concentration on the morphology and photoluminescence of synthesized ZnO nanomaterials

was identified using a M13 pVIII phage display library and employed as an additive during aqueous-based ZnO syn-thesis at 65 C. Unlike most other well-studied ZnO-binding sequences which are strongly basic (pI [ pH 7), the 8-mer peptide was overall acidic (pI \ pH 7) in char-acter, including only a single basic residue. The selected peptide strongly influenced ZnO nanostructure formation. Morphology and optical emission properties were found to be dependent on the concentration of peptide additive. Using lower peptide concentrations (\0.1 mM), single crystal hexagonal rods and platelets were produced, and using higher peptide concentrations (C0.1 mM), poly-crystalline layered platelets, yarn-like structures, and microspheres were assembled. Photoluminescence analysis revealed a characteristic ZnO band-edge peak, as well as sub-bandgap emission peaks. Defect-related green emis-sion, typically associated with surface-related oxygen and zinc vacancies, was significantly reduced by the peptide additive, while blue emission, attributable to oxygen and zinc interstitials, emerged with increased peptide concen-trations. Peptide-directed synthesis of ZnO materials may be useful for gas sensing and photocatalytic applications in which properly engineered morphology and defect levels have demonstrated enhanced performance.