Inspired by green corrosion chemistry and wastewater remediation: A high-performance Zn anode with locally gradient microstructures

Driven by the new energy industry’s rapid growth, surging demand for lithium/zinc raw materials has accelerated polymetallic ore mining. Cadmium ions (Cd 2+ ), as co-existing heavy metal pollutants in smelting wastewater, pose environmental challenges while inspiring innovative solutions. This work introduces a green corrosion approach achieving > 99% removal of Cd 2+ , Pb 2+ , and Cu 2+ via Zn foil functionalization. During controlled corrosion, Cd 2+ are directly reduced to metallic Cd by Zn, while generated Zn 2+ form Zn 5 (OH) 8 Cl 2 ⋅H 2 O (ZCH) nanosheet arrays in situ . A gelatin-assisted low-temperature pyrolysis then converts these products into a carbon/Cd/zinc oxide (ZO-Cd-GC) multilayer on Zn foil, which creates a local gradient in Zn anode properties: enhanced zincophilicity, improved Zn 2+ desolvation, and suppressed hydrogen evolution from electrolyte to anode. The resulting Zn@ZO-Cd-GC anode enables uniform electron/ion transport, fast kinetics, suppressed side reactions, and dendrite-free deposition. Symmetric cells with this anode exhibit an ultra-long lifetime exceeding 6000 h at 2 mA cm −2 /1 mAh cm −2 and stable operation without short-circuiting at 20 mA cm −2 . A Zn@ZO-Cd-GC||NH 4 V 4 O 10 pouch cell delivers a high discharge capacity and maintains stability over 2000 cycles at 33.75 mA cm −2 . • A green corrosion strategy was proposed to simultaneously realize wastewater purification and Zn anode modification. • Locally gradient microstructure was in situ formed on the Zn surface with the assistance of gelatin. • The modified Zn anode achieved superior performance in both half cells and full cells. • Combined experiments and theoretical calculations revealed the modification mechanism in details.