Ultra-fast surface reconstruction enabled by the built-in electric field in heterostructured CoS2/CuS for water electrolysis
Han Man, Jingjing Feng, Shaofei Wang, Shuyang Li, Peng Li, Huiwen He, Wioletta Raróg‐Pilecka, Jie Zhao, Jichao Zhang, Fang Fang, Dalin Sun, Yongtao Li, Yun Song
Abstract
Transition-metal chalcogenides (TMCs) show great potential as highly efficient and cost-effective electrocatalysts for oxygen evolution reaction (OER). Yet the electrochemical conversion into oxides/hydroxides remains poorly understood. In this work, we develop a built-in, electric-field-induced surface reconstruction strategy for ultra-fast self-activation of transition metal sites in self-supporting CoS2/CuS heterostructures. The activated CoS2/CuS grown on carbon cloth with oxygenated surface species displays an outstanding OER electrocatalytic activity with ultra-low overpotentials of only 136 mV at the current density of 10 mA cm−2 and 266 mV at 100 mA cm−2 in 1.0 M KOH. Comparative studies via synchrotron radiation X-ray absorption spectroscopy and theoretical calculations are employed to elucidate that the built-in electric field within heterointerfaces significantly promotes the reconstruction efficiency by decreasing the formation energy of (oxy)hydroxide species. We believe this work provides new perspectives to conceive catalysts with ultra-low overpotentials and complements the fundamental comprehension of TMCs’ self-reconstruction mechanism.