Fe‐Incorporated Ni/MoO2 Hollow Heterostructure Nanorod Arrays for High‐Efficiency Overall Water Splitting in Alkaline and Seawater Media

Abstract Developing high‐efficiency and cost‐effective bifunctional catalysts for water electrolysis is fascinating but still remains challenging. Thus, diverse strategies have been utilized to boost the activity toward oxygen/hydrogen evolution reactions (OER/HER) for water splitting. Among them, composition and structure engineering as an effective strategy has received extensive attention. Here, by means of a self‐sacrificing template strategy and simultaneous regulation of the composition and structure, Fe‐incorporated Ni/MoO 2 heterostructural (NiFe/Fe‐MoO 2 ) hollow nanorod arrays are designed and constructed. Benefiting from abundant catalytic active sites, high intrinsic activity, and fast reaction kinetics, NiFe/Fe‐MoO 2 exhibits superior OER (η 20 = 213 and 219 mV) and Pt‐like HER activity (η 10 = 34 and 38 mV), respectively, in 1 m KOH and alkaline seawater media. This results in attractive prospects in alkaline water and seawater electrolysis with only voltages of 1.48 and 1.51 V, and 1.69 and 1.73 V to achieve current densities of 10 and 100 mA cm −2 , respectively, superior to the Pt/C and RuO 2 pair as a benchmark. Undoubtedly, this work provides a beneficial approach to the design and construction of noble‐metal‐free bifunctional catalysts toward efficient hydrogen production from alkaline water and seawater electrolysis.