Manganese-cobalt hydroxide nanosheets anchored on a hollow sulfur-doped bimetallic MOF for high-performance supercapacitors and the hydrogen evolution reaction in alkaline media.

Abstract

Nonmetallic doping and in situ growth techniques for designing electrode materials with excellent electrocatalytic activity are effective strategies to enhance the electrochemical performance. Bifunctional electrode materials for supercapacitors (SCs) and the hydrogen evolution reaction (HER) have attracted great interest due to their potential applications in green energy storage and conversion. Herein, the bimetallic MnCo LDH is anchored on a hollow sulfur (S)-doped MnCo-MOF-74 surface, forming a poplar flower-like 3D composite which is used for SCs and the HER in alkaline media. The fabricated S-MnCo-MOF-74@MnCo LDH/NF electrode exhibits a favorable specific capacitance of 1875.4 F g-1 at 1 A g-1 and steady long-term cycling performance. Moreover, the assembled HSC using S-MnCo-MOF-7@MnCo LDH/NF as the cathode material and active carbon (AC) as the anode material shows 546.4 F g-1 capacitance (1 A g-1) with a maximum energy density of 58 W h kg-1 at 14 000 W kg-1 power density. As an electrocatalyst, S-MnCo-MOF-7@MnCo LDH/NF exhibits excellent HER properties with a small Tafel slope of 128.9 mV dec-1 a low overpotential of 197 mV at 10 mA cm-2 and durable performance for 10 hours in alkaline media. The present work provides insights into understanding and designing active electrode materials for stable hydrogen evolution and high-performing supercapacitors in an alkaline environment.