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

BaTiO3 particles with 2% Al dopant concentration were reported by Dudem et al. in J. Mater. Chem. A, 2018, 6, 16101 to exhibit a high remnant polarisation and piezoelectric coefficient, being hence employed to efficiently enhance the output performance of hybrid piezo/triboelectric nanogenerators. However, in this comment we express concerns regarding the discussion of the piezoelectric coefficient and the interpretation or reliability of the ferroelectric results in that publication. We also discuss an inconsistency between the Al doping content and the presented results, and contend that other material data analyses were contradictory or incorrect and that many important details were missing.