Many methods used to synthesize efficient reducing agents of Fe and Al-layered double hydroxide (Fe/Al-LDH) nanosheets against oxidizing contaminants often require the use of unstable bivalent iron salts and long aging times at ambient temperatures. Here, we developed an easy-to-operate, environment-friendly, and scaled-up electrochemical engineering method without adding metal salts to synthesize Fe/Al-LDHs via an electrolytic reaction of active metal electrodes (Fe and Al). The process resulted in the growth of thin hexagonal Fe/Al-LDHs with a lateral size of approximately 100 nm and thickness of approximately 32 nm. The crystallization process of Fe/Al-LDHs strongly relied on the crystal nucleus of the first precipitate Al(OH)(3) and the Fe chemical valence. The oxidation state of Fe was markedly influenced by hydroxyl ions that formed on the cathode surface and the oxygen evolution reaction at high current density (i). The fast and simple manufacturing technique not only had high yield (approximately 0.2 g of Fe/Al-LDHs was obtained when i was 2 mA/cm(2) within 25 min) but also afforded Fe/Al-LDHs with excellent reducibility for the removal of Cr(VI). This study demonstrated an attractive option for the rapid and large-scale synthesis of Fe/Al-LDHs to enhance their application prospects. (C) 2019 Elsevier Inc. All rights reserved.