Corrosion-assisted large-scale production of hierarchical iron rusts/Ni(OH)₂ nanosheet-on-microsphere arrays for efficient electrocatalysis

Iron corrosion is always harmful to our industrial manufacture and thus numerous effects have been conducted for corrosion protection. However, the detrimental corrosion may be applied to produce serviceable materials, resulting in “upcycling waste into wealth”. Herein, a novel corrosion engineering is employed to fabricate hierarchical iron rusts/Ni(OH)₂ nanosheet-on-microsphere arrays as effective oxygen evolution reaction (OER) electrocatalysts. Through physically mixing the fabricated ultrathin iron rusts with Ni(OH)₂ microspheres, the as-prepared catalyst requires an overpotential of only 318 mV to achieve the current density of 20 mA cm⁻². Besides, negligible increasement of overpotential is observed after continuous chronopotentiometric determination for 30 h. The excellent OER property is attributed to the formed oxygen bridges of Fe–O–Ni on the solid-solid contact sites, which promote oxidation of Ni²⁺ specieses via the interfacial Fe³⁺ of iron rusts (FeOOH). In particular, a large-scale production of 2.968 g iron rusts/Ni(OH)₂ catalysts was successfully prepared by using this simple, lowcost yet valid corrosion engineering. This work provides a novel avenue towards large-scale production of efficient OER catalysts by combing with corrosion science, which is beneficial for boosting the progress of water splitting.