Tailored porosity development in carbons via Zn²⁺ monodispersion: Fitting supercapacitors

Abstract

Here, we propose a novel, electrochemical preparation of in situ N-doped alginate-based carbon precursors with monodispersed zinc ions. Obtained carbons were evaluated by spectroscopic (FTIR, Raman and XPS), textural (N2 physisorption), microscopic (TEM) and elemental (SEM-EDS) descriptors to establish their distinctive features originating from different synthetic procedures. Carbons characteristics were assessed in view of several carbonization temperatures applied for their preparation from alginate precursors, and individual and joint effect of zinc and nitrogen on the precursor. Obtained Zn monodispersion, emphasizes the significance of electrochemical preparation, allowing increasing temperature to induce changes from its ionic form to carbonate and oxide, while at 800 °C ZnO further reduces and evaporates. Since homogeneously dispersed Zn species acts as porosity evolving agent during carbonization, a substantial surface area is developed, in the range 718–1056 m2 g−1. Textural properties revealed that the use of rivanol as an N-doping agent shields carbon scaffold from porosity overdevelopment. The alginate-based carbons are probed as electrode materials for supercapacitors and surface/textural properties connected to electrochemical results. Controlled electrochemical dispersion of zinc and, in situ N–doping with rivanol, developed a bio-based material of excellent capacitance (265 F g−1 @5 mV s−1) and stability. This study reflects key features in material design necessary for engineering upcoming supercapacitors.