This study reports enhanced current (CERCS) and energy efficiency (EERCS) of reactive chlorine species (RCS) generation on Ir7Ta3Oy anode by Ti/Bi mixed metal oxide heterojunction layers despite reductions in pseudo-capacitance and film conductivity. In potentiostatic electrolysis of 50 mM NaCl solutions, dramatic improvement (0.61 mmol cm(-2) hr(-1) at 2.5 V NHE) was noted by simple coating of thin (similar to 2 mu m) TiO2 layer from ball-milled TiO2 nanoparticle (80-100 nm) suspension, even with moderate elevation in voltammetric wave. Decoration of Bi2O3 particles (1 - 2 mu m) showed limited or adverse effects for RCS generation and stability. However, Bi-doped TiO2 layers prepared from polyol-mediated or co-precipitation methods marked the highest CERCS (similar to 100%) and EERCS (8.16 mmol Wh(-1) at( )2.5 V NHE) by increased mixing level and effective shift in surface charge. Surface center dot OH exclusively mediated the RCS generation whose further transformation to higher oxide could be restrained by the heterojunction layer. (C) 2020 The Authors. Published by Elsevier Inc.