Urchin-like hierarchical ruthenium cobalt oxide nanosheets on Ti3C2TxMXene as a binder-free bifunctional electrode for overall water splitting and supercapacitors

Synthesizing efficient electrode materials for water splitting and supercapacitors is essential for developing clean electrochemical energy conversion/storage devices. In the present work, we report the construction of a ruthenium cobalt oxide (RuCo2O4)/Ti3C2Tx MXene hybrid by electrophoretic deposition of Ti3C2Tx MXene on nickel foam (NF) followed by RuCo2O4 nanostructure growth through an electrodeposition process. Owing to the strong interactions between RuCo2O4 and Ti3C2Tx sheets, which are verified by density functional theory (DFT)-based simulations, RuCo2O4/Ti3C2Tx MXene@NF can serve as a bifunctional electrode for both water splitting and supercapacitor applications. This electrode exhibits outstanding electrocatalytic activity with low overpotentials of 170 and 68 mV at 100 A m-2 toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The RuCo2O4/Ti3C2Tx MXene@NF-based alkaline water-splitting cell only requires 1.62 V to achieve a current density of 100 A m-2, which is much better than that of RuO2@NF and Pt/C@NF-assembled cells (1.75 V@100 A m-2). The symmetric supercapacitor (SSC)-assembled electrode displays a high specific capacitance of 229 F g-1 at 3 A g-1. The experimental results, complemented with theoretical insights, provide an effective strategy to prepare multifunctional materials for electrocatalysis and energy storage applications.