Effects of Nitric Acid Activation on Textural, Surface, and Supercapacitive Properties of Ultra-Small Carbon Nanospheres

Abstract

Chemical activation of carbon materials is critical to modify their textural and surface properties in an effort to optimize their supercapacitive performance as electrode materials for supercapacitors. This present work investigates the effects of nitric acid activation on the textural, surface, and supercapacitive properties of u ltra-small carbon nanospheres with a uniform size of 24 nm synthesized through a unique catalytic emulsion polymerization strategy. Nitric acid activation has been undertaken at different temperatures for various time. The effects of these two activation parameters have been systematically examined, with some important correlations established. The optimum activation conditions for achieving the best supercapacitive performance in different aqueous electrolytes have been identified.

Synthesis of Highly Uniform N-Doped Porous Carbon Spheres Derived from Their Phenolic-Resin-Based Analogues for High Performance Supercapacitors

“…If we further reduce the amount of phenol to 0.28 and 0.24 g, the size of the resulting PS becomes 91 and 67 nm, respectively, while remaining highly uniform as shown in Figure S6. Meanwhile, the size of the derived NCS correspondingly decreases to 69 and 51 nm, which is close to the smallest carbon spheres reported so far. , …”

“…On the basis of the emulsion polymerization process, , a plausible scheme is provided to elucidate the preparation of polymer spheres as shown in Figure . The first stage of hydrothermal reaction was carried out at 80 °C.…”

“…Synthesis and Characterization of Polymer and Carbon Nanospheres. On the basis of the emulsion polymerization process, 3,42 a plausible scheme is provided to elucidate the preparation of polymer spheres as shown in The first stage of hydrothermal reaction was carried out at 80 °C. After the addition of formaldehyde, the reaction between phenol and formaldehyde gives rise to the mixtures of addition and condensation compounds which can react further to form a cross-linking network.…”

“…Meanwhile, the size of the derived NCS correspondingly decreases to 69 and 51 nm, which is close to the smallest carbon spheres reported so far. 3,42 Similarly, the size of PS and CS can also be precisely controlled by changing the amounts of phenol and formaldehyde, meanwhile keeping their molar ratio at 1:2.46 (phenol to formaldehyde) in the case of the adaption of CTAB as a stabilizing agent. If the amount of phenol is increased to 0.38 g, the size of as-synthesized PS concomitantly becomes around 270 nm, and the size of the derived NCS is about 205 nm as shown in Figure 6a and b.…”

Monodisperse Porous Carbon Nanospheres with Ultra‐High Surface Area for Energy Storage in Electrochemical Capacitors

“…Another strategy comprises the physical/chemical activation of polymeric spheres made up of thermosetting polymers (i. e., phenolic resins, saccharide-based hydrochar, polypyrrole, polyacrylonitrile, etc. ), which can be produced following different methodologies, including the Stöber method, [17] the benzoxazine approach, [18,19] emulsion-polymerization, [20,21] as well as hydrothermal carbonization. [22] The conversion of polymeric spheres into porous carbon is usually carried out by a two-step process that first involves the carbonization of polymeric material and, subsequently, a heattreatment with an oxidant substance that serves as activating agent.…”