MOF derived tri-metallic CoNiMn hydroxide assembled on carbon cloth for hybrid supercapacitor and hydrogen evolution

Abstract

Polymetallic hydroxides are promising electrode materials for supercapacitors and electrocatalysis due to their unique physical and chemical properties. Herein, carbon cloth self-supported cobalt‑nickel‑manganese hydroxide (CoNiMn-OH/CC) composites were synthesized by a facile hydrothermal method with zeolite imidazolate framework-67 (ZIF-67) as a template. The results indicate that the hydroxides maintain the morphology of ZIF-67 template, while the addition of Mn can affect the redox behavior and enhance the electrochemical activity of metal hydroxides. Therefore, the prepared CoNiMn-OH with ultrathin edge-surface stacked nanosheets structure can promote electron/ion transfer, which induces to better charge storage kinetics and activity for supercapacitors and hydrogen evolution reaction (HER). In-situ Raman spectra combined density functional theory calculations co-revealed the reaction mechanism. The optimized CoNi3Mn1-OH nanosheets has a high specific capacity of 955.7C g−1 at 1 A g−1 and excellent rate performance with 91.1 % capacitance retention (870.7C g−1 at 10 A g−1). The hybrid supercapacitor device with CoNi3Mn1-OH as the positive electrode and activated carbon (AC) as the negative electrode has an energy density of up to 30 Wh kg−1, a power density of 0.8 kW kg−1, and excellent cycling stability (78.5 % capacity retention after 10000 cycles at 5 A g−1). In addition, the CoNi3Mn1-OH composite with tuned Ni and Mn metal ratios has a low HER overpotential of 202 mV at 10 mA cm−2.