Electrocatalysis by H₂–O₂ membrane-free fuel cell enzymes in aqueous microenvironments confined by an ionic liquid

Abstract

A synaptic enzyme fuel cell comprising wet hydrogenase and bilirubin oxidase electrodes surrounded by ionic liquid shell.

Dual gas-diffusion membrane- and mediatorless dihydrogen/air-breathing biofuel cell operating at room temperature

“…The power density is given in Fig. 7 (B) and the maximum power density reached 6.1  0.4 mW cm 2 at a 0.72 V cell voltage, much higher than that of other H2 biofuel cells in the literature [20][21][22][23][24][25][26][27][28][29][30].…”

“…is typically reduced by multi-copper oxidases (MCOs) at the biocathode are known as clean and highly efficient energy conversion devices that have attracted increasing attention for establishing a "hydrogen economy" [20][21][22][23][24][25][26][27][28][29][30][31].…”

“…In addition, a gas-diffusion system is useful for suppressing the oxidative inactivation that occurs at positive electrode potentials and competitively with the catalytic cycle, and is another important issue in hydrogenase applications [76]. On the other hand, to avoid the risk of explosion, the compartmentalization of fuel cells [20,21,23,25,27,31] and operation at low concentrations of H2and/or O2 [22,24,26,[28][29][30] are frequently explored. The former requires sophisticated cell construction and the latter results in low power density.…”

“…Enzymatic biofuel cells (EBFCs) are devices for converting chemical energy into electrical energy that utilize enzymes as electrocatalysts for the oxidation of fuels at the anode and the reduction of dioxygen (O2) or hydrogen peroxide at the cathode [1][2][3][4]. In principle, a variety of compounds, such as sugar [5][6][7][8][9][10][11][12][13], alcohol [14][15][16][17], formate [18,19] and dihydrogen (H2) [20][21][22][23][24][25][26][27][28][29][30][31], can be utilized as fuels of EBFCs. Thanks to substrate specificity and high catalytic efficiency under mild conditions (e.g., room temperature, around neutral pH), EBFCs are expected to be one of the next-generation energy conversion systems, comparable to conventional fuel cells, such as polymer electrolyte fuel cell [32]; however, the low power densities of EBFCs hinder technological applications [1][2][3][4].…”

High-Power Formate/Dioxygen Biofuel Cell Based on Mediated Electron Transfer Type Bioelectrocatalysis

“…In principle, a variety of compounds such as sugar, − alcohol, − formate (HCOO – ), and dihydrogen (H 2 ) − can be utilized as fuels for biofuel cells. In particular, H 2 /dioxygen (O 2 ) and HCOO – /O 2 biofuel cells can completely utilize the energy (in a two-electron oxidation of the fuels) with a high theoretical standard electromotive force (ca.…”