Ni₃N–CeO₂ Heterostructure Bifunctional Catalysts for Electrochemical Water Splitting

Abstract Developing low‐cost and high‐efficient bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is greatly significant for water electrolysis. Here, Ni 3 N‐CeO 2 /NF heterostructure is synthesized on the nickel foam, and it exhibits excellent HER and OER performance. As a result, the water electrolyzer based on Ni 3 N‐CeO 2 /NF bifunctional catalyst only needs 1.515 V@10 mA cm −2 , significantly better than that of Pt/C||IrO 2 catalysts. In situ characterizations unveil that CeO 2 plays completely different roles in HER and OER processes. In situ infrared spectroscopy and density functional theory calculations indicate that the introduction of CeO 2 can optimizes the structure of interface water, and the synergistic effect of Ni 3 N and CeO 2 improve the HER activity significantly, while the in situ Raman spectra reveal that CeO 2 accelerates the reconstruction of O V (oxygen vacancy)‐rich NiOOH for boosting OER. This study clearly unlocks the different catalytic mechanisms of CeO 2 for boosting the HER and OER activity of Ni 3 N for water splitting, which provides the useful guidance for designing the high‐performance bifunctional catalysts for water splitting.