Morphological and Interfacial Engineering of Cobalt-Based Electrocatalysts by Carbon Dots for Enhanced Water Splitting

Cobalt-based electrocatalysts for water splitting have attracted extensive research interests. However, the single function, poor performances, and restriction of electrolyte pH value have restricted their further development. Here, morphological and interfacial engineering of cobalt nanoparticles, are performed by the incorporation of carbon dots (CDs). Typically, the nitrogen-doped carbon-encapsulated cobalt nano particles (N-C@Co NPs) were in situ constructed for electrocatalytic overall water splitting, exhibiting superior hydrogen evolution performances in both acid and alkaline media with the overpotential of 137 and 134 mV at 10 mA.cm(-2), respectively, and excellent oxygen evolution performances in alkaline media with the overpotential of 353 mV at 10 mA.cm(-2). Such performances outperform the majority of previously reported Co-based electrocatalysts and are comparable to many excellent nonprecious metal based electrocatalysts. It is found that CDs have significant impact on fabricating a distinct morphology of catalysts and bonding structure between N-C and Co NPs, and synergistic effects between the N-C and Co NPs for water splitting are revealed. Furthermore, as a proof concept, the proposed strategy was further verified by CDs-decorated cobaltosic oxide nanoparticles (CDs@Co3O4 NPs) with enhanced OER activities (a overpotential of 304 mV at 10 mA.cm(-2)). This work provides an approach for the synthesis of various stable metal-based carbon hybrids with high-performance photo/electrocatalystic activities.