Thin NiFeCr-LDHs nanosheets promoted by g-C3N4: a highly active electrocatalyst for oxygen evolution reaction

NiFeCr layered double hydroxides (NiFeCr-LDHs) supported on graphitic carbon nitride (g-C₃N₄) hybrids (NiFeCr-LDHs/g-C₃N₄) are synthesized and used as an electrocatalyst for oxygen evolution reaction (OER) in alkaline media. Effect of g-C₃N₄ on the structure and OER performance of NiFeCr-LDHs are investigated in detail. g-C₃N₄ can promote the formation of thin NiFeCr-LDHs nanosheets, thereby enhancing both the number of active sites and OER activity. X-ray photoelectron spectra measurements confirm the electronic interaction between g-C₃N₄ and NiFeCr-LDHs nanosheets. The OER performance of NiFeCr-LDHs/g-C₃N₄ hybrids highly relates to the weight ratio of g-C₃N₄ to NiFeCr-LDHs. When the weight ratio of g-C₃N₄ to NiFeCr-LDHs is 5%, the corresponding electrocatalyst shows the best OER activity. The component optimized NiFeCr-LDHs/g-C₃N₄ hybrids display the overpotential of ∼223 mV at 10 mA cm^-2 and Tafel slope of 89 mV dec^-1 for OER in 1 M KOH solution, which is better than that of pristine NiFeCr-LDHs, bare g-C₃N₄, and commercial RuO₂.