Operando High‐Valence Cr‐Modified NiFe Hydroxides for Water Oxidation
Ming Hua Wang, Zhen Xin Lou, Xuefeng Wu, Yuanwei Liu, Jia Zhao, Kai Sun, Wen Xin Li, Jiacheng Chen, Hai Yang Yuan, Minghui Zhu, Sheng Dai, Peng Fei Liu, Hua Gui Yang
Abstract
Abstract High‐valence metal‐doped multimetal (oxy)hydroxides outperform noble metal electrocatalysts for the oxygen evolution reaction (OER) owing to the modified energetics between 3d metals and high‐valence dopants. However, the rational design of sufficient and subtle modulators is still challenging. With a multimetal layered double hydroxide (LDH) as the OER catalyst, this study introduces a series of operando high‐valence dopants (Cr, Ru, Ce, and V), which can restrict the 3+ valence states in the LDH template to prevent phase separation and operando transfer to the >3+ valence states for sufficient electronic interaction during the OER process. Through density functional theory simulations, ultrathin Cr‐doped NiFe (NiFeCr) LDH is synthesized with strong electronic interaction between Cr dopants and NiFe bimetallic sites, evidenced by X‐ray absorption spectroscopy. The resulting NiFeCr‐LDH catalyzes the OER with ultralow overpotentials of 189 and 284 mV, obtaining current densities of 10 and 1000 mA cm –2 , respectively. Further, a NiFeCr‐LDH anode is coupled in the anion exchange membrane electrolyzers to promote alkaline water splitting and CO 2 ‐to‐CO electrolysis, which achieves low full cell voltages at high current densities.