Unusual Redox Behavior of Ruthenocene Confined in the Micropores of Activated Carbon

Abstract

We demonstrate reversible charge/discharge in ruthenocene, RuCp 2 (Cp = η 5 -C 5 H 5 ), using activated carbon (AC) as a support. RuCp 2 is supported in the micropores of AC as clusters consisting of multiple RuCp 2 molecules via gas-phase adsorption. Upon subsequent electrochemical oxidation using an aqueous H 2 SO 4 electrolyte, the clusters are disassembled and the RuCp 2 molecules are finely dispersed in the micropores. The resulting RuCp 2 has a large contact area with conductive carbon surfaces, thereby realizing rapid charge transfer at the contact interface. Consequently, rapid charge storage occurs via the reversible redox reaction of the supported RuCp 2 in aqueous H 2 SO 4 without dimerization or disproportionation reactions, which is confirmed by Xray absorption spectroscopy. Since hybridization can produce different properties of the host and guest materials, their infinite combinations would have the possibility to yield properties far surpassing those of existing materials.

Hybridization of a Polymer inside the Pores of Activated Carbon and Pore Structural Characterization

“…We have recently reported the hybridization of host and guest materials toward high-performance electrode materials by introducing redox-active materials into the pores of porous carbons. − Conductive polymers ( e.g. , polyaniline) − and metal oxides ( e.g.…”

Metal-Free Homocoupling of Pyrene inside the Pores of Mesoporous Carbons via Electrochemical Oxidation: Application for Electrochemical Capacitors

“…Therefore, the finely dispersed PYD inside the pores of MgO-Cs undergoes rapid charge transfer at the large contact interfaces. We have demonstrated the superior power densities of electrochemical capacitors than those of EDLCs using redox-active organic compounds 18 , 20 − 22 and redox-active organometallic complex, 23 which were hybridized inside the pores of porous carbons. That is, the redox reactions of redox-active materials are not intrinsically inferior to the EDL formation in terms of the power density.…”

“…GC was conducted in a potential range of −0.1 to 0.8 V. The gravimetric capacitance ( C g F g –1 ) was calculated according to the following equation: where I (A) is the current, Δ t (s) is the time from −0.1 to 0.8 V, m is the weight (g) of MgO-C and PY in the working electrode, and Δ V (V) is fixed to 0.9 V irrespective of the current density. The volumetric capacitance ( C V F cm –3 ) was calculated, assuming that PYD was hybridized inside the pores of MgO-C without the volume expansion of MgO-C particles, using the following equation: 22 , 23 …”

Synthesis of Polynorbornadiene within the Pores of Activated Carbons: Effects on EDLC and Hydrogen Adsorption Performances

“…Cyclic voltammetry (CV) was conducted at a sweep rate of 1 mV s –1 in a potential range of −0.1 to 0.8 V. The volumetric current ( I v A cm –3 ) was calculated assuming that PNBD was hybridized inside the pores of AC without volume expansion of the AC particles, using the current per 1 g of AC ( I g‑AC A g –1 ) and the weight of AC per 1 cm 3 of the electrode ( W AC g cm –3 ) according to the following equations , where I g is the gravimetric current per 1 g of the AC/PNBD hybrids (A g –1 ), ρ AC is the electrode density of AC-2 (0.49 g cm –3 ) or AC-4 (0.33 g cm –3 ), Y is the weight percentage of PNBD in the hybrid ( Y ). In addition, w AC , w CB , and w PTFE are the weights of AC, CB, and PTFE in the electrode, respectively.…”

“…Since PNBD is hybridized within the pores of AC, the number of the AC particles per unit electrode volume does not change as far as the same AC is used. 13,15,17,18 Therefore, the volumetric current has a linear correlation with the normalized current per 1 g of AC (A g AC −1…”