Cobalt Nanoparticles Encapsulated in N-Doped Carbon on the Surface of MXene (Ti<sub>3</sub>C<sub>2</sub>) Play a Key Role for Electroreduction of Oxygen
Haridas Parse, Indrajit Patil, Bhalchandra Kakade, Anita Swami
Abstract
Owing to the unique and significant properties of the layered two-dimensional (2D) structure of MXenes, they are being widely employed for various electrochemical device applications such as Li-ion batteries (LIBs), supercapacitors (SC), and hydrogen storage. Less attention has been paid toward their catalytic applications (energy conversion), perhaps due to the non-ideal electrochemical performance. Therefore, in the present study, we are reporting the preparation and electrocatalytic ability of MXene (Ti3C2Tx) and metal organic framework (Cobalt-MOF)-derived composites (Co-NC/Ti3C2-T). Interestingly, the optimized composite Co-NC/Ti3C2-800 reveals improved electrocatalytic oxygen reduction reaction (ORR) activity with a reasonably higher onset potential (Eonset) of 1.04 V versus reversible hydrogen electrode (RHE), a current density (JL) of 4.8 mA/cm2, and a half wave potential (E1/2) of 0.93 V versus RHE. Furthermore, the first order kinetics mechanism of ORR and percentage peroxide yield (HO2–) were investigated using RRDE measurement. Finally, an optimized catalyst Co-NC/Ti3C2-800 demonstrates robust potential cycling performance (after 10k) over Pt/C under similar experimental conditions. Superior electrochemical performance of as-prepared nanocomposite materials is attributed to the redox centers of Co and the direct growth of a N-doped carbon network around a skeleton of Ti3C2Tx that act as efficient charge transfer channel after redox reactions. Moreover, the formation of TiO2 on the surface of MXene flakes may decrease the mass transport limitation and help to boost the electrocatalytic activity. Thus, the hybrid of MXene and Co-MOF (Co-NC/Ti3C2-800) could be hopefully be a substitute for state-of-the-art catalysts, especially under alkaline conditions.