We have demonstrated a high performance piezoelectric nanogenerator by scanning a diamond-coated conductive tip on ZnO nanorod arrays in an AFM system with contact-mode. About 95% ZnO nanorods generate piezoelectric current due to the excellent mechanical and electrical properties of the tip. The tip's nitrogen-doped diamond coating is the key factor to maintain effective physical contact and electrical contact to ZnO nanorods, leading to efficient piezoelectric generation. Rectifying n(+)-n heterojunction is formed when the nitrogen-doped diamond tip contacted with a ZnO nanorod, which plays an important role in accumulating and releasing piezoelectric charges of the piezoelectric nanogenerator. Our research indicates that conductive diamond film is an ideal electrode for this type of piezoelectric nanogenerator. (C) 2011 Elsevier B.V. All rights reserved.