Self-assembled hierarchical porous layered double hydroxides by solvothermal method and their application for capacitors

Solvothermal synthesis of NiAl double hydroxide microspheres on a nickel foam-graphene as an electrode material for pseudo-capacitors

“…30,31 To describe the possible formation of the NiAl DHMs, which are spherical layered double hydroxides (LDHs), we refer to the Ostwald ripening mechanism which involves the nucleation and growth of NiAl LDH crystals. 29 In other words, in the presence of a mixture of Ni 2+ and Al 3+ salts, the continuous supply of carbonate (CO 2 − ) and hydroxide (OH − ) at a controlled rate from urea decomposition leads to the formation of the founding double hydroxide nanoparticles. 14 The whole evolution/growth process could be likened to the three-stage process reported in previous studies 32 which involves a fast nucleation of amorphous primary particles, followed by crystal growth and final self-assembly.…”

“…This value is comparable to or even larger than those reported in earlier studies for NiAl-double hydroxide materials published elsewhere. 17,29,48 Fig. 5(b) shows the corresponding pore size distribution with a major pore diameter ranging from 1.7 to 4 nm which shows the successful inclusion of both microporous and mesoporous sites.…”

“…In this regard, most recent studies are therefore inclined towards achieving well-defined micro/nanostructures with excellent surface properties, better electrochemical performance, higher electrical conductivity and adequate pore size distribution in order to enhance interface reactions and enhance the mass/electron transfer of the electroactive species during faradaic redox reactions. 17,29 Song et al 29 used a solvothermal technique in which the ratio of ethanol/water was varied to obtain different structures of NiAl LDHs. The sample prepared with 100% ethanol had a specific surface area of about 300 m 2 g −1 .…”

P3HT:PCBM/nickel-aluminum layered double hydroxide-graphene foam composites for supercapacitor electrodes

“…The nickel foam with graphene was then immersed in 3.0M hydrochloric acid (HCl) at 80 ᵒC for 8 hours to etch away the nickel template completely and thereafter rinsed several times in deionized water to obtain the graphene foam. NiAl-LDH composites were synthesized by adopting a facile solvothermal method reported in earlier work [3]. Typically, 2.400 g of urea, 2.139 g of Ni(NO 3 ) 2 and 0.724 g of Al(NO 3 ) 3 salts were dissolved in 80 ml of a pre-sonicated deionized water/ethanol solution containing graphene foam.…”

“…Supercapacitors (SCs, or ultracapacitors) and hybrid solid-state batteries are but a few examples of the most recent technological innovations in the field of electrical energy storage [1][2][3][4][5][6][7][8][9]. Among the latter, SCs possess higher power density and longer cycle life, but lower energy density.…”