Enhanced CO₂ electroreduction: Via interaction of dangling S bonds and Co sites in cobalt phthalocyanine/ZnIn₂S₄ hybrids

The efficient electrochemical reduction of CO₂ to CO in aqueous electrolyte is very interesting. Due to the critical electron-transfer step during the activation of CO₂, it is important to design efficient strategies to engineer the electronic properties of catalysts to improve the electrochemical performance. Herein cobalt phthalocyanine (CoPc) supported on ZnIn₂S₄ (ZIS) nanosheets was synthesized. It was found that the hybrids showed excellent performance for CO₂ electroreduction to CO in aqueous solution. The faradaic efficiency, current density and mass activity could reach 93%, 8 mA cm^-2 and 266 mA mg_(CoPc)^-1, respectively. Introduction of Zn-defects resulted in dangling S bonds in the ZIS support, which interacted with Co active sites of CoPc via strong Co-S interaction. Mechanistic studies revealed that the enhancement of CO production over CoPc by Co-S interaction originated from the eased CO₂ activation.