Comparison of metal oxide-carbon composites derived from natural alginate gels

Metal oxide-carbon composites (MOCCs) derived from sodium alginate gels were prepared through a facile and green ionic gelation method. Various polyvalent cations (Mn2+, Fe3+, and Zn2+) were used to crosslink sodium alginate to produce gels, following which the gels were carbonized under nitrogen flow to yield MOCCs. X-ray diffraction, scanning electron microscopy, and Raman spectra can character the as-prepared materials structural and morphological characters and thermogravimetric analysis. The electrochemical behavior of the as-prepared materials was studied by applying to cyclic voltammetry, galvanostatic charge-discharge measurements, and electrochemical impedance spectroscopy in 6 M KOH electrolyte. The highest specific capacitance (161 F g(-1) at 0.5 A g(-1)) was obtained for the Fe oxide-doped carbon material (MOCC-Fe), which displayed a good life cycle with only a 10% capacitance decline after 2000 cycles.