Highly Efficient Oxygen Evolution on the Tubular Array of the Mesoporous NiMoO4@NiFeS Heterostructure

Developing efficient and stable oxygen evolution reaction (OER) electrocatalysts is crucial to the practical application of water electrolysis for hydrogen production. Herein, a tubular array of a mesoporous NiMoO4@NiFeS heterostructure was anchored on nickel foam through successive hydrothermal processing, liquid etching and direct sulfur vulcanization. The efficient charge transfer, phase transition and full exposure of active sites at the heterostructure’s interfaces, as well as its superhydrophilic surface, endow NiMoO4@NiFeS with exceptional OER activity. A series of electrochemical experiments indicate that in 1.0 mol·L−1 KOH, NiMoO4@NiFeS delivers overpotentials as low as 180 and 223 mV at current densities of 10 and 100 mA cm−2, respectively, and that a Tafel slope of merely 25.9 mV dec−1 is achieved on NiMoO4@NiFeS, evidencing that the tubular array of the mesoporous NiMoO4@NiFeS heterostructure significantly facilitates the interfacial transfer of charge/mass and the decrease in the energy barrier of the rate-determining step. This work provides valuable insights for the construction of an efficient and low-cost electrocatalyst with hierarchical mesoporous core–shell structures.