Ce Site in Amorphous Iron Oxyhydroxide Nanosheet toward Enhanced Electrochemical Water Oxidation

Abstract

Iron oxyhydroxide has been considered an auspicious electrocatalyst for the oxygen evolution reaction (OER) in alkaline water electrolysis due to its suitable electronic structure and abundant reserves. However, Fe-based materials seriously suffer from the tradeoff between activity and stability at a high current density above 100 mA cm−2. In this work, the Ce atom is introduced into the amorphous iron oxyhydroxide (i.e., CeFeOxHy) nanosheet to simultaneously improve the intrinsic electrocatalytic activity and stability for OER through regulating the redox property of iron oxyhydroxide. In particular, the Ce substitution leads to the distorted octahedral crystal structure of CeFeOxHy, along with a regulated coordination site. The CeFeOxHy electrode exhibits a low overpotential of 250 mV at 100 mA cm−2 with a small Tafel slope of 35.1 mVdec−1. Moreover, the CeFeOxHy electrode can continuously work for 300 h at 100 mA cm−2. When applying the CeFeOxHy nanosheet electrode as the anode and coupling it with the platinum mesh cathode, the cell voltage for overall water splitting can be lowered to 1.47 V at 10 mA cm−2. This work offers a design strategy for highly active, low-cost, and durable material through interfacing high valent metals with earth-abundant oxides/hydroxides.