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A biomimetic nickel bis-diphosphine complex incorporating the amino acid arginine in the outer coordination sphere was immobilized on modified carbon nanotubes (CNTs) through electrostatic interactions. The functionalized redox nanomaterial exhibits reversible electrocatalytic activity for the H2/2 H+ interconversion from pH 0 to 9, with catalytic preference for H2 oxidation at all pH values. The high activity of the complex over a wide pH range allows us to integrate this bio-inspired nanomaterial either in an enzymatic fuel cell together with a multicopper oxidase at the cathode, or in a proton exchange membrane fuel cell (PEMFC) using Pt/C at the cathode. The Ni-based PEMFC reaches 14 mW cm−2, only six-times-less as compared to full-Pt conventional PEMFC. The Pt-free enzyme-based fuel cell delivers ≈2 mW cm−2, a new efficiency record for a hydrogen biofuel cell with base metal catalysts. [ABSTRACT FROM AUTHOR]

In this work, we have designed and compared functionalized carbon-nanotube-based electrodes for the electrocatalytic oxidation of NADH. We show that oxidation of NADH at neutral pH values can be performed by pristine multi-walled carbon nanotubes (MWCNT) and directly wired diaphorase or ruthenium phenanthrolinequinone molecular catalysts. Glucose dehydrogenase was immobilized on these MWCNT electrodes by an activated-ester-modified pyrene linker. Glucose-oxidizing bioelectrodes were compared and integrated into a bucky-paper-based glucose/O2 biofuel cell, using a bilirubin-oxidase-modified bucky-paper cathode. The best configuration was obtained using a NADH-oxidizing molecular catalyst at the anode. The biofuel cell exhibits an open-circuit voltage of 0.62 V and delivers a power output of 0.47 mW cm−2. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (RGO) was covalently functionalized by the in situ generation and reduction of anthraquinone diazonium salt. Deposition on multi-wall carbon nanotube (MWCNT) electrodes prevents the aggregation of RGO nanosheets and allows the stable deposition of modified graphene, accompanied with excellent electron transfer properties. Laccases were immobilized on the nanostructured electrode by the interaction between the anthraquinone moiety and the laccase hydrophobic pocket located near the T1 copper center. The MWCNT/f-RGO electrode exhibits efficient bioelectrocatalytic oxygen reduction, with current densities of up to 0.9 mA cm−2. [ABSTRACT FROM AUTHOR]

Orientation of the enzyme Laccase enabling direct electron transfer with functionalized reduced graphene oxide in the presence of carbon nanotubes led to a high performance biocathode. The image represents anthraquinone ‐ functionalized reduced graphene oxide sheets orienting and wiring Laccase enzymes. The electrons involved in the electrocatalytic reduction of oxygen to water are supplied by the surrounding carbon nanotube matrix and transferred via graphene to the enzyme. For more details, see the Communication by S. Cosnier and co ‐ workers on page 3198 ff. [ABSTRACT FROM AUTHOR]