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In this study, FeCo 2 O 4 @Co 3 O 4 bifunctional catalysts with a unique structure combining nanosheets and nanowires were prepared on nickel foam by a simple hydrothermal + annealing method. The catalysts exhibited excellent catalytic activity for hydrogen production during urea electrooxidation reaction (UOR) and ethanol oxidation reaction (EOR). For UOR, the potential at 10 mA/cm2 current density is 1.387 V and the tafel slope is 67 mV/dec. In the configured two-electrode electrolytic cell, the FeCo 2 O 4 @Co 3 O 4 catalysts in the UOR and EOR processes required only 1.425 and 1.471 V, respectively, to produce a current density of 10 mA/cm2, which is much less than that of the (oxygen evolution reaction) OER (1.640 V). In addition, the current density remained stable at a fixed potential during a long time (20 h) i-t test in the urea solution. [Display omitted] • FeCo 2 O 4 @Co 3 O 4 nanocomposites were synthesized by a two-step hydrothermal + annealing method. • FeCo 2 O 4 @Co 3 O 4 electrode showed better electrocatalytic properties of UOR and EOR than that of OER. • FeCo 2 O 4 @Co 3 O 4 /NF//Pt electrolyzer displayed low potentials and stable long cycle life. • The study presented a promising FeCo 2 O 4 @Co 3 O 4 electrode for energy-saving H 2 production. [ABSTRACT FROM AUTHOR]

In this study, CoS/MnCo 2 O 4 -MnO 2 (CMM) nanocomposites were synthesised by hydrothermal + electrochemical deposition and their electrochemical properties were systematically investigated for supercapacitors and energy-saving H 2 production. As an electrode material for supercapacitor, CMM achieves a specific capacitance of 2320F g−1 at 1 A/g, and maintains a specific capacitance of 1216F g−1 at 10 A/g. It also shows good cycling stability (72.8 % capacitance retention after 8000 cycles). The aqueous asymmetric supercapacitor (CMM//AC ASC) assembled from CMM electrodes (positive) and AC electrodes (negative) exhibited high energy storage capacity (887.86F g−1 specific capacitance at a current density of 1 A/g), good rate performance and cycling stability. In addition, CMM shows excellent UOR and MOR performances energy-saving H 2 production. compared to OER (1.635 V) at 20 mA cm−2, The potentials was reduced by 213 mV for UOR and 233 mV for MOR, respectively. MMC electrodes maintain a stable catalytic current for 100h and 55h, respectively. Furthermore, As a bifunctional catalyst for both UOR (MOR) and HER, CMM exhibits excellent catalytic and stability performances.Therefore, this study shows the promising practical applications of CMM nanocomposites for energy storage and energy-saving H 2 production. [Display omitted] • CoS/MnCo 2 O 4 -MnO 2 (CMM) nanocomposites were synthesised by hydrothermal and then electrochemical deposition. • CMM achieves a specific capacitance of 2320F g−1 at 1 A g−1, and maintains a specific capacitance of 1216F g−1 at 10 A g−1. It also shows good cycling stability (72.8 % capacitance retention after 8000 cycles). • The aqueous asymmetric supercapacitor (CMM//AC ASC) assembled from CMM electrodes (positive) and AC electrodes (negative) exhibited high energy storage capacity (887.86F g−1 specific capacitance at a current density of 1 A g−1). • CMM shows excellent UOR and MOR performances energy-saving H 2 production. compared to OER (1.635 V) at 20 mA cm−2, The potentials was reduced by 213 mV for UOR and 233 mV for MOR, respectively. In this study, CoS/MnCo 2 O 4 -MnO 2 (CMM) nanocomposites were synthesized by hydrothermal and then electrochemical deposition. Their electrochemical properties were systematically investigated for supercapacitors and energy-saving H 2 production. As an electrode material for supercapacitor, CMM demonstrates a specific capacitance of 2320F g−1 at 1 A/g, and maintains a specific capacitance of 1216F g−1 at 10 A/g. It also shows 72.8 % capacitance retention after 8000 cycles. The aqueous asymmetric supercapacitor exhibited high energy storage capacity (887.86F g−1 specific capacitance at a current density of 1 A/g), good rate performance and cycling stability. Besides, CMM shows outstanding urea oxidation reaction(UOR) and glycol oxidation reaction (MOR) performances for H 2 production. Compared to oxygen evolution reaction (OER) (1.635 V) at 20 mA cm−2, the potentials were reduced by 213 mV for UOR and 233 mV for MOR, respectively. Therefore, this study shows the promising practical applications of CMM nanocomposites for energy storage and energy-saving H 2 production. [ABSTRACT FROM AUTHOR]

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−1at 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. [Display omitted] • 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. [ABSTRACT FROM AUTHOR]