Comment on “Enhancing the Output Performance of Hybrid Nanogenerators Based on Al-Doped Batio3 Composite Films: a Self-Powered Utility System for Portable Electronics”, by B. Dudem, L. K. Bharat, H. Patnam, A. R. Mule and J. S. Yu, J. Mater. Chem. A, 2018, 6, 16101