Urchin-like hierarchical ruthenium cobalt oxide nanosheets on Ti 3 C 2 T x MXene 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 (RuCo 2 O 4 )/Ti 3 C 2 T x MXene hybrid by electrophoretic deposition of Ti 3 C 2 T x MXene on nickel foam (NF) followed by RuCo 2 O 4 nanostructure growth through an electrodeposition process. Owing to the strong interactions between RuCo 2 O 4 and Ti 3 C 2 T x sheets, which are verified by density functional theory (DFT)-based simulations, RuCo 2 O 4 /Ti 3 C 2 T x 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 RuCo 2 O 4 /Ti 3 C 2 T x 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 RuO 2 @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.