Multifunctional Co3O4/Ti3C2Tx MXene nanocomposites for integrated all solid-state asymmetric supercapacitors and energy-saving electrochemical systems of H2 production by urea and alcohols electrolysis

Co 3 O 4 /Ti 3 C 2 T x MXene nanocomposites have been fabricated by vacuum filtration and hydrothermal-annealing methods, and their electrochemical performance were investigated for energy storage and conversion, systematically. As electrode materials, Co 3 O 4 /Ti 3 C 2 T x MXene nanocomposites in 6 M KOH solution demonstrated the specific capacitance of 240.1 F g −1 at 0.1 A g −1 and the long-term cycle stability. The solid-state asymmetric supercapacitors exhibited an operating potential window of 1.4 V, a specific capacitance of 97.9 F g −1 at 0.25 A g −1 , an energy density of 95.9 Wh kg −1 at a power density of 630.4 W kg −1 , and excellent long-term durability. Furthermore, the connected solid-state asymmetric supercapacitors inseries and parallels presented the promising practical applications. Besides, Co 3 O 4 /Ti 3 C 2 T x nanocomposites displayed outstanding catalytic behaviors for energy-saving H 2 generation by urea and alcohols electrolysis. The electrolyzer in KOH + CH 3 CH 2 OH electrolyte required only 1.33 V potential to deliver the current density of 0.5 A g −1 . Especially, the elctrochemical system of H 2 production by The electrolyzer and the powered solid-state asymmetric supercapacitors based on Co 3 O 4 /Ti 3 C 2 T x nanocomposites was constructed, demonstrating outstanding properties of H 2 production. Therefore, this study not only shows enormous potential of Co 3 O 4 /Ti 3 C 2 T x nanocomposites as a portable power supply but also indicates its great opportunities in energy-saving H 2 production in practical applications. The Co 3 O 4 /Ti 3 C 2 T x nanocomposites were successfully synthesized by vacuum filtration and hydrothermal-annealing methods, which demonstrated excellent capacitive properties for energy storage and catalytic behaviors for H 2 production. The constructed electrochemical systems with Co 3 O 4 /Ti 3 C 2 T x nanocomposites//AC solid-state asymmetric supercapacitors and Co 3 O 4 /Ti 3 C 2 T x nanocomposites//Pt electrolyzers displayed the outstanding electrocatalytic behaviors for energy-saving H 2 production. Therefore, the study present enormous potential of Co 3 O 4 /Ti 3 C 2 T x nanocomposites as a portable energy storage in practical applications, but also indicate its great opportunities in energy-saving H 2 production. • The Co 3 O 4 /Ti 3 C 2 T x nanocomposites were successfully synthesized. • The Co 3 O 4 /Ti 3 C 2 T x nanocomposites//AC supercapacitors exhibited outstanding performances of energy storage. • The Co 3 O 4 /Ti 3 C 2 T x nanocomposites demonstrated good UOR and MOR performances. • The performances of Co 3 O 4 /Ti 3 C 2 T x nanocomposites//AC supercapacitors with different manners were investigated. • The electrochemical systems for energy-saving H 2 production were constructed with Co 3 O 4 /Ti 3 C 2 T x nanocomposites.