Interference effect of nitrogen-doped CQDs on tailoring nanostructure of CoMoP for improving high-effective water splitting

The construction of bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is significant for developing water splitting technology. The carbon-based non-noble metal catalysts could be regarded as a preferred alternative to Pt-based materials in water splitting, but very rarely Pt-like activity has been obtained by non-noble metal catalysts. Herein, NCQDs/CoMoP/NF bifunctional catalysts were designed and synthesized by the coupling relationships between N-doped carbon quantum dots (NCQDs) and metal ions. The abundant functional groups on the surfaces of CQDs can effectively coordinate with metal ions with empty d orbitals to generate the stable composites. Meanwhile, the formation of metal nanoparticles can be restricted by the introduction of CQDs to form smaller crystals with stable nanostructures, thereby preventing the agglomeration and further growth of metal nanoparticles. The NCQDs-100/CoMoP/NF electrode shows a low overpotential of 65 mV (10 mA cm−2) for HER and 370 mV (100 mA cm−2) for OER in a 1.0 M KOH system. Furthermore, the constructed NCQDs-100/CoMoP/NF couple can reveal a small cell voltage of 1.75 V to reach the large current density of 50 mA cm−2.