In Situ Coupling of Carbon Dots with Co‐ZIF Nanoarrays Enabling Highly Efficient Oxygen Evolution Electrocatalysis

Metal‐organic frameworks (MOFs) are regarded as one promising class of precatalysts for electrocatalytic oxygen evolution reaction (OER), yet most of them suffer from poor conductivity and lack of coordinatively unsaturated metal sites, which hinders the fast electrochemical reconstruction and thus a poor OER activity. To address this issue, a unique heterocomposite has been constructed by in situ inserting carbon dots (CDs) into cobalt‐based zeolitic imidazolate framework (Co‐ZIF) nanosheet arrays (Co‐ZIF/CDs/CC) in the presence of carbon cloth (CC) via one‐pot coprecipitation for alkaline OER. Benefiting from the synergism between CDs and Co‐ZIF subunits such as superior conductivity, strong charge interaction as well as abundant metal sites exposure, the Co‐ZIF/CDs/CC exhibits an enhanced promotion effect for OER and contributes to the deep phase transformation from CDs‐coupled Co‐ZIF to CDs‐coupled active CoOOH. As expected, the achieved Co‐ZIF/CDs/CC only requires an overpotential of 226 mV to deliver 10 mA cm−2 in 1.0 M KOH, which is lower than that of Co‐ZIF/CC and superior to most previously reported CC‐supported MOF precatalysts. Moreover, it can also maintain a large current density of 100 mA cm−2 for 24 h with negligible activity decay. A hierarchical array electrode assembled by in situ embedding carbon dots (CDs) within Co‐ZIF nanosheets has been designed as an oxygen evolution reaction (OER) precatalyst, which delivered excellent activity and stability. The exceptional performance has been credited to the coupling effect between CDs and Co‐ZIF, which increases the specific surface area, introduces physical defects, and promotes the surface charge transfer.