MOF-Derived\nNi/NiO‑C Nanocomposites as Bifunctional\nElectrocatalysts Capable of Driving Both ORR and OER

Bifunctional electrocatalysts, capable of efficiently\ndriving both\nthe oxygen reduction reaction (ORR) and the oxygen evolution reaction\n(OER), are crucial for advancing electrochemical processes. While\nnoble-metal-based catalysts are widely recognized for their role in\noxygen processes, current state-of-the-art designs are limited to\neither ORR or OER activity, presenting a notable research gap. In\naddressing this challenge, we have developed a novel <b>Ni/NiO-C</b> nanocomposite catalyst derived from a nickel-based metal–organic\nframework (<b>Ni-SKU-5</b>). For the ORR, the <b>Ni/NiO-C</b> catalyst exhibits an onset potential of 0.95 V vs RHE in a 1.0 M\nKOH solution, coupled with a Tafel slope of −99 mV dec<sup>–1</sup> at 1600 rpm. Moreover, the catalyst displays excellent\nstability, maintaining a performance of over 90% after 10 h of continuous\nreaction. Furthermore, the catalyst proves effective in the OER, boasting\nan overpotential of 370 mV (at 10 mA cm<sup>–2</sup>) and a\nTafel slope of 114 mV dec<sup>–1</sup>, highlighting its bifunctionality.\nThe bifunctional overpotential of the <b>Ni/NiO-C</b> composite\nis measured at 820 mV, surpassing that of the 20% Pt/C electrocatalyst\n(860 mV), highlighting its potential for practical applications. Comparative\nexperiments establish the origin of the robust bifunctional reactivity\ntoward the conformal hybrid structure, porous framework, and the synergistic\neffect operating among the constituents of the nanocomposite.