Chlorine-assisted synthesis of CuCo2S4@(Cu,Co)2Cl(OH)3 heterostructures with an efficient nanointerface for electrocatalytic oxygen evolution

The demand for sustainable energy sources urges the development of efficient and earth-abundant electrocatalysts . Herein, chlorine assisted ion-exchange and in-situ sulfurization processes were combined to construct CuCo 2 S 4 @(Cu,Co) 2 Cl(OH) 3 heterostructures from Cu(OH) 2 nanoarrays. Chlorine element in the cobalt source stimulated the formation of (Cu,Co) 2 Cl(OH) 3 precursor, and further facilitated partial transformation of the precursor to CuCo 2 S 4 on the surface to achieve composite structure. The mixed valences of Co element (Co 3+ in CuCo 2 S 4 and Co 2+ in (Cu,Co) 2 Cl(OH) 3 ) and O S interpenetrated nanointerface in the composite catalysts provided low electron transfer resistance for good alkaline oxygen evolution reaction (OER) activities. In 1 mol L −1 KOH electrolyte, the overpotentials of the optimal composite catalyst reached 253 and 290 mV respectively at the current density of 20 and 50 mA cm −2 , which is comparable to the activity of commercial Ir/C (281 mV@20 mA cm −2 ). These findings could provide opportunities for designing effective and inexpensive composite electrocatalysts through nanointerface engineering strategy.