Yttrium- and Cerium-Codoped Ultrathin Metal–Organic Framework Nanosheet Arrays for High-Efficiency Electrocatalytic Overall Water Splitting

The construction of low-cost, highly efficient, and stable electrocatalysts is a significant challenge for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we report a facile strategy to fabricate ultrathin metal–organic framework (MOF) nanosheet arrays doped with two rare-earth elements, Y and Ce, and self-supported on nickel foam (NF) to enhance the HER and OER performance by constructing abundant active sites and bimetallic synergistic effects. The NiYCe-MOF/NF features an ultrathin nanosheet array structure and is uniformly and richly codoped by Y and Ce. When it was explored as both the anode and cathode electrocatalysts for overall water splitting, it achieved 10 mA cm –2 at 136 and 245 mV for the HER and OER in an alkaline electrolyte, respectively. Notably, an extremely low cell voltage of 1.54 V was required to achieve 100 mA cm –2 in 1.0 M KOH solution, making it a promising substitute for noble-metal catalysts.