Hierarchical nanoassembly of Ni3S2-MoS2 interconnected with CeO2 as a highly remarkable hybrid electrocatalyst for enhancing water oxidation and energy storage

Abstract

Emerging earth-abundant multifunctional electrocatalysts with highly efficient performance are important substitutes for replacing the expensive noble metal catalysts to attain sustainable electrochemical water splitting and supercapacitor applications. Therefore, we developed a well-interconnected Ni3S2-MoS2-CeO2 (NMC) nanostructure as a multifunctional electrocatalyst for the utilization in dual purposes, mainly energy conversion and storage applications. In alkaline conditions, the NMC-1 exhibits remarkable oxygen evolution reaction (OER) performances of lower over potential (206.03 mV at 10 mA/cm2) coupled with the lowest Tafel slope (40.19 mV·dec−1). The NMC-1 further shows excellent stability, where the durability of the electrocatalyst was verified after a considerable number of cyclic voltammetry (5000 cycles) and chronopotentiometry. The coexistence of the Ce3+ and Ce4+ oxidation states generates a favorable environment for surface oxygen ion exchange. The inherent stability of CeO2 facilitates a strong and intimate electrochemical coupling with NiOOH. This synergistic interaction between CeO2, MoS2, and NiOOH further enhances the performance of the catalytic system. Notably, the hybrid structure of NMC-1 exhibited superior supercapacitor performance (417 F/g at 1 A/g). The fabricated asymmetric supercapacitor device showed efficient performance by attaining a high energy density of 4.84 Wh kg−1 at a power density of 72 W kg−1. According to the intrinsic properties of each material in NMC and the existence of synergy owing to the outstanding interfacial contact between the compounds in NMC, reasonably abundant surface-active sites are available for attaining rapid charge transfer, enhancing the inherent activity and durability of the catalyst, which is the key reason for better OER and supercapacitor performance. This study provides useful understandings into the strategic design of advanced multifunctional electrode materials for next-generation applications.