Cr-doped CoFe layered double hydroxides: Highly efficient and robust bifunctional electrocatalyst for the oxidation of water and urea

Oxygen evolution reaction (OER) and urea oxidation reaction (UOR) play important roles in the field of hydrogen energy preparation and pollution treatment. In this work, we successfully synthesize a Cr doped CoFe layered double hydroxides (LDH) nanosheets array with uniform growth on a nickel-foam (NF). The partially oxidized Cr6+ during the process of oxidation could adjust the electronic structure and stabilize the high-valence active sites by virtue of its strong electron-withdrawing ability. The calculation of density functional theory (DFT) shows that the incorporation of Cr into CoFe LDH could obviously overcome the step of H2O adsorption during the OER progress. Therefore, the CoFeCr LDH/NF electrode exhibits superior OER performance. Furthermore, when acted as a UOR electrode, its performance is also satisfying. The design of the CoFeCr LDH/NF would hew out a brand-new route to construct more bifunctional electrodes for electrocatalytic water splitting in an alkaline solution with or without urea.