Electrocatalysis for Fuel Cells at Enzyme-Modified Electrodes - Fuel Cell Catalysis: A Surface Science Approach - page 621

to 60 8C by the hydrogenase from a bacterium that does not live at extreme tempera-
tures [L´ger et al., 2002], electrocatalytic currents that are stable over a month or more
by laccase on a 2-aminoanthracene electrode [Blanford et al., 2007] or a covalently
linked hydrogenase [Alonso-Lomillo et al., 2007], and electrocatalysis in demanding
environments such as within a plant [Mano et al., 2003]. Isolation of novel enzymes
may also lead to biological catalysts with enhanced stability.
Improved attachment and stabilization of enzymes on surfaces is one key area that
requires significant attention in the development of enzyme electrocatalysis for fuel
cells. Advances may come from a mixture of genetics (introduction of useful surface
residues for chemical linkage) and electrode modification and coupling chemistry.
It will also be important to increase electroactive coverage, and this may involve
high suface area electrode supports or multilayer adsorption of enzyme, or a combi-
nation of these approaches. Design possibilities for enzyme fuel cells are at an early
stage, and dialogue between enzyme electrochemists and fuel cell scientists may be
important in advancing design of devices that exploit enzyme electrocatalysts.
The large molecular size and ambient operation of enzymes means that they are
likely to be more suited to niche applications rather than to high-power devices, but
there are important lessons to be learnt from biological catalysis that occurs in con-
ditions under which conventional metal catalysts would fail. Development of synthetic
catalysts inspired by the chemistry (although not necessarily the structures) of enzyme
active sites may lead to future catalysts with new and improved properties.

ACKNOWLEDGMENTS

K. A. Vincent is a Royal Society University Research Fellow. H. A. Heering is financially sup-
ported by a VIDI grant from The Netherlands Organization for Scientific Research (NWO).
Fraser A. Armstrong is thanked for helpful discussion and comments on the manuscript.

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