Ce-doped nanorod-like NiFe-MOF with coordination substitution based on in situ co-doping method for boosting the oxygen evolution reaction

Abstract

Heteroatom-doped metal–organic frameworks (MOFs) have been widely used in OER catalysis. However, the effects of doping methods on these materials have rarely been reported. Herein, the structure and activity of Ce-doped nanorod-like MOFs (CeNi_1.6Fe-MIL-53 and Ce@Ni_1.6Fe-MIL-53) prepared by employing in situ co-doping and surface doping methods were analyzed. The structure of Ni_1.6Fe-MIL-53 can be optimized at different levels by different Ce-introduction ways. In contrast, the in situ co-doping of Ce increases the number of active sites and better optimizes the band structure. Therefore, CeNi_1.6Fe-MIL-53 exhibited good OER activity, which required an overpotential of only 277 mV at a current density of 10 mA cm⁻², a Tafel slope of 31.03 mV dec⁻¹ and a good stability maintained for 60 h. Moreover, when CeNi_1.6Fe-MIL-53 was coupled as an electrolytic cell, the cell showed a low cell potential (1.54 V at 10 mA cm⁻²) and good stability (maintained for 33 h).