Enhanced oxygen evolution reaction through improved lattice oxygen activity via carbon dots incorporation into MOFs.

Emerging of the lattice oxygen mechanism (LOM) provides a new opportunity for enhancing oxygen evolution reaction (OER) activity. However, its stability suffers from metal cation dissolution and lattice oxygen anionic redox chemistry. In this paper, carbon dots (CDs)-modified nickel-iron MOF (Metal-Organic Framework) nanosheets (NiFe-BDC/CDs) were prepared for efficient OER electrocatalysis. The introduction of CDs promotes the hybridization of the O 2p band in the MOF with the metal 3d band near the Fermi level, leading to improved involvement of lattice oxygen in the oxygen evolution reaction. Additionally, C-M bonds formed between CDs and metal sites in MOF enhanced the stability of electrocatalyst. As results, the prepared NiFe-BDC/CDs electrodes demonstrated a current density of 100 mA cm at overpotentials of 235 and 250 mV in alkaline freshwater and alkaline seawater, respectively, and a remarkable stability in alkaline seawater at 500 mA cm for >100 h. This study provides a simple and versatile strategy for the design of OER electrocatalysts with highly active transition metal-based MOFs.