Ternary cobalt–iron–manganese layered double hydroxides with 1D/2D hierarchical nanostructure for oxygen evolution reaction and urea oxidation reaction

Developing high-efficient and stable electrocatalysts for oxygen evolution reaction (OER) is crucial for water splitting and metal-air batteries. Herein, ternary CoFe_1−XMn_X (0 <X < 1) layered double hydroxides (LDHs) grown on nickel form (NF) with nanosheet-nanowires (1D/2D) hierarchical nanostructure are synthesized. The introduction of Mn causes the change of crystal phase, morphology, and electronic structure of CoFe-LDH through electron transfer from Co/Fe to Mn, which provides the whole merit structural features and synergistic effect. Further experimental results exhibit that CoFe_0.75Mn_0.25-LDH possesses superior OER performance, which only requires overpotentials of 243 and 298 mV to reach 20 and 100 mA cm⁻². The remodeling of LDHs in the OER process is also discussed to further explore the OER catalytic mechanism. In addition, CoFe_0.75Mn_0.25-LDH can also be utilized to the urea oxidation reaction (UOR), which requests a low potential of 1.367 V to reach 10 mA cm⁻². A solar driven water splitting system is assembled and acquires the current density of 10 mA cm⁻² at the low cell voltage of 1.58 V. This work offers an effective approach to boost the OER and UOR performance of CoFe-LDH based bifunctional electrocatalysts.