MOF-derived MnCe3.67C6Permeable microflower: A robust electrocatalyst for oxygen evolution reaction

Abstract

To enhance the accessibility of hydrogen fuel production, there is a pressing need for the development of efficient catalysts possessing abundant catalytic active sites, robust stability, and a substantial surface area conducive to both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this study, we present a novel electrocatalyst derived from a metal-organic framework (MOF) precursor, specifically MnCe<inf>3.67</inf>C<inf>6</inf>, synthesized through a cost-effective and straightforward pyrolysis process. This process involves the transformation of carefully designed porous spongy conjoined tapeworm like morphology at 973.15 K carburized temperature and which transform into conjoined nanowires when carburization temperature increases from 1073.15 to 1273.15 K into aggregated nanospheres, with the MOF serving as a carbon template. The structural, morphological, and compositional characteristics of the resulting MnCe<inf>3.67</inf>C<inf>6</inf> catalyst were thoroughly investigated using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Remarkably, the MnCe<inf>3.67</inf>C<inf>6</inf> catalyst exhibits outstanding OER activity, manifesting a significantly reduced potential of 231 mV at current density of 10 mAcm−2 in alkaline media, thereby facilitating efficient charge transfer. Furthermore, the fabricated MnCe<inf>3.67</inf>C<inf>6</inf>-700 electrocatalyst demonstrates a decreased Tafel slope of 68mVdec−1, indicative of a favorable kinetic mechanism for the resultant material. The electrochemical active surface increases considerably after fabrication of composite MnCe<inf>3.67</inf>C<inf>6</inf>-700 (C<inf>dl</inf> = 77 mFcm−2) as compared to Mn–Ce/MOF (C<inf>dl</inf> = 34 mFcm−2). Moreover, the higher OER activity is also complemented with extraordinary stability of MnCe<inf>3.67</inf>C<inf>6</inf>-700 that is capable of performing oxygen evolution reaction for more than 150 h, making it attractive candidate for the commercial utilization. Notably, the enhanced catalytic performance of MnCe<inf>3.67</inf>C<inf>6</inf> can be attributed primarily to the well-dispersed cerium on the carbon surface, which provides an enlarged active surface area replete with catalytic sites, as well as the dynamic charge transfer of electrons depicted in XPS spectrum, thereby enhancing electrochemical properties and paving the way for future applications. © 2024 Elsevier B.V., All rights reserved.