Interface Engineering of Ni(x)S(y)@MnO(x)H(y) Nanorods to Efficiently Enhance Overall-Water-Splitting Activity and Stability

HIGHLIGHTS: Three-dimensional (3D) core‐shell heterostructured Ni(x)S(y)@MnO(x)H(y) nanorods grown on nickel foam (Ni(x)S(y)@MnO(x)H(y)/NF) were successfully fabricated via a simple hydrothermal reaction and a subsequent electrodeposition process. The fabricated Ni(x)S(y)@MnO(x)H(y)/NF shows outstanding bifunctional activity and stability for hydrogen evolution reaction and oxygen evolution reaction, as well as overall‐water‐splitting performance. The main origins are the interface engineering of Ni(x)S(y)@MnO(x)H(y), the shell‐protection characteristic of MnO(x)H(y), and the 3D open nanorod structure, which remarkably endow the electrocatalyst with high activity and stability. ABSTRACT: Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional (3D) core‐shell Ni(x)S(y)@MnO(x)H(y) heterostructure nanorods grown on nickel foam (Ni(x)S(y)@MnO(x)H(y)/NF) as a bifunctional electrocatalyst. Ni(x)S(y)@MnO(x)H(y)/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn‐S bonds connect the heterostructure interfaces of Ni(x)S(y)@MnO(x)H(y), leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction (OER). Besides, as an efficient protective shell, the MnO(x)H(y) dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, Ni(x)S(y)@MnO(x)H(y)/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm(–2), respectively, along with high stability of 150 h at 100 mA cm(–2). Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm(–2), accompanied by excellent stability at 100 mA cm(–2) for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40820-022-00860-2.