Thermal Conversion of Hollow Nickel-Organic Framework into Bimetallic FeNi3 Alloy Embedded in Carbon Materials as Efficient OER Electrocatalyst

Abstract Rapid deployment of renewable energy causes a significant change in environmental benefits. Thus, the transition metal-based electrocatalysts are developed to achieve efficient water splitting. Here a simple three-step method is adopted to successfully synthesize a type of hollow MOF-derived three-dimensional carbonaceous matrix that is randomly loaded with numerous FeNi3 alloy nanoparticles (NiFeC). In this work, the as-obtained NiFeC-800-5 (carbonization temperature: 800 oC; pyrolysis rate: 5 oC/min) shows an excellent oxygen evolution reaction catalytic activity in 1.0 M KOH electrolyte, with a low overpotential of 269 mV at 10 mA cm-2 and a low Tafel slope of 72 mV dec-1. Moreover, it exhibits an ultrastable durability after being electrolyzed continuously for 10 h, which is originated from these fine alloys encapsulated into the hierarchically porous carbonaceous material. Finally, we have proposed morphological and chemical changes for the NiFeC-800-5 sample, in which the solid MOF precursor will be gradually etched into the hollow morphology by the strong hydrolysis of Fe(III) ions at high temperature, and the optimal carbonization temperature and heating rate are also well investigated. Moreover, the above approach can be used to obtain other MOF derived bimetallic alloy nanoparticles encapsulated into carbon materials for the energy conversion and storage applications.