  Nickel-based layered double hydroxides (LDHs) are promising electrode
materials in the fields of energy storage (supercapacitors) and conversion
(urea oxidation). The rational construction of atomic and electronic structure
is crucial for nickel-based LDHs to realize their satisfactory electrochemical
performance. Herein, we report a facile, ecofriendly, one-step synthesis
process to construct petal-like oxygen-deficient NiAl-LDH nanosheets for hybrid
super-capacitors (HSCs) and urea oxidation reaction (UOR). The asprepared
NiAl-LDH nanosheets with rich oxygen vacancies possess a large specific surface
area of 216.6 m2 g-1 and a desirable electronic conductivity of 3.45 * 10-4 S
cm-1 to deliver an ultra-high specific capacitance of 2801 F g-1 (700 C g-1) at
1 A g-1. Furthermore, high specific energy of 50.0 W h kg-1 at 400 W kg-1 and
excellent cycle stability with 91% capacitance retention after 10,000 cycles
are achieved by the NiAl-LDHs/CFP (carbon fiber paper) (+)//YP-80F (a
commercial activated carbon) (-) HSC. Besides, NiAl-LDH nanosheets also work as
an efficient electrocatalyst for UOR, which only requires 1.42 V vs. reversible
hydrogen electrode to drive 10 mA cm-2 in 1 mol L-1 KOH with 0.33 mol L-1 urea.
This remarkable performance is superior to most reported values of previous
candidates owing to the thin structure of NiAl-LDH nanosheets for exposing more
active sites and abundant oxygen vacancies. In addition, various reaction
parameters are investigated to optimize the electrochemical performance. In
general, this work paves a new way for the architecture of multifunctional
nanostructured energy materials.
