Phosphorization Endows Ni–Co–Fe Ternary Oxide Templated by SBA‐15 With Higher Catalytic Performance in Oxygen Evolution Reaction

In the present work, oxygen evolution reaction (OER) catalysts based on Co–Fe–Ni oxides were prepared for electrochemical water splitting. To improve the specific area and thus expose more active sites, Ni–Co–Fe ternary oxides were prepared in confined mesopores of SBA‐15 with a morphology of regular nanorod. The Ni–Co–Fe oxides exhibited higher catalytic activity than the Co–Fe binary oxide, due to the synergy of transition metals. Additionally, to further improve the catalytic performance, an oxide with the lowest overpotential and Tafel slope was phosphorized for more active sites. As expected, this phosphorized oxide displayed an excellent catalytic performance in OER. For example, its overpotential was as low as 246 mV at 10 mA cm −2 and its Tafel slope was reduced to 65.6 mV·Dec −1 . Besides, it had a double‐layer capacitance as high as 31.2 mF cm −2 and an impedance as low as 45.6 Ω. Both parameters are far better than their oxide precursor. Those improvements have been attributed to its mesoscopic morphology and the substitution of oxygen by phosphorus, both of which provided more active sites participating in OER.