Morphology and Crystal Planes Effects on Supercapacitance of CeO₂ Nanostructures: Electrochemical and Molecular Dynamics Studies

Abstract

Nano cerium oxide (CeO2) is a promising supercapacitor material, but the effect of morphology on charge storage capacity remains elusive. To determine this effect, three different morphologies, nanorods, cubes, and particles are synthesized by a one‐step hydrothermal process. Electrochemical evaluation through cyclic voltammetry and galvanostatic charge–discharge techniques reveals specific capacitance to be strongly dependent on the nanostructure morphology. The highest specific capacitance in nanorods (162.47 F g−1) is due to the substantially larger surface area relative to the other two morphologies and the predominant exposure of the highly reactive {110} and {100} planes. At comparable surface areas, exposed crystal planes exhibit a profound effect on charge storage. The exposure of highly reactive {100} planes in nanocubes induce a greater specific capacitance compared to nanoparticles, which are dominated by the less reactive {111} facets. The experimental findings are supported by reactivity maps of the nanostructures generated by molecular dynamics simulations. This study indicates that supercapacitors with higher charge storage can be designed through a nanostructure morphology selection strategy.

Strongly Bound Surface Water Affects the Shape Evolution of Cerium Oxide Nanoparticles

“…19 This is due to the presence of a vacancy, which binds 3+ cations at the surface, as shown in previous experimental and theoretical studies. 51 Hydroxyl groups can fill the vacant oxygen lattice site and "heal" the surface enabling the surface cations to recover coordination. Associatively adsorbed water cannot adequately enable this healing and thus surface oxygen vacancies promote dissociation of water molecules.…”

Mesoporous Zr-doped CeO2 nanostructures as superior supercapacitor electrode with significantly enhanced specific capacity and excellent cycling stability

“…Supercapacitor, as one of the most promising clean and renewable energy storage techniques, has advantages such as high power density, short charging time, high rate capacity and good cycling stability [1][2][3][4]. In recent years, many metal oxide nanomaterials have been explored as the supercapacitor electrode materials [5], including RuO2 [6], Co3O4 [7,8], NiO [9,10], MnO2 [11,12], CuO [13], SnO2 [14,15], V2O5 [16], Fe3O4 [17,18], α-Fe2O3 [19], TiO2 [20] and CeO2 [21,22]. Among them, CeO2 is an eco-friendly electrode material with low toxicity and excellent chemical stability, and can be operated in various acidic and alkaline electrolytes [23][24][25][26].…”

“…Accordingly, various CeO2 nanostructures have been prepared to improve their electrochemical performance, such as nanospheres [21], nanorods [22,28,29], nanowires [21], nanoparticles [27,30] and porous nanostructures [31], etc. However, at present the specific capacity produced from these CeO2 nanostructures reported in literature are still quite low.…”

Multiscale Modeling of Agglomerated Ceria Nanoparticles: Interface Stability and Oxygen Vacancy Formation

“…On the theoretical side, Sayle and co-workers have used force-field simulations to investigate structure-property relationships for ceria nanostructures and have for example investigated nanocubes, nanorods, nanochains, and mesoporous structures (Sayle et al, 2005, 2011; Jeyaranjan et al, 2018). In one of their studies, ceria nanochains were generated via oriented attachment (OA) and used as model systems to explain the mechanism for ceria nanorod formation (Sayle et al, 2011).…”