Highly Efficient Oxygen Evolution on the Tubular Array of 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, tubular array of 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, engender NiMoO₄@NiFeS a highly effective OER electrocatalyst. 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 merely 25.9 mV dec^-1 is achieved on NiMoO₄@NiFeS, evidencing that the tubular array of 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 efficient and low-cost electrocatalyst with hierarchical mesoporous core-shell structures.