Platinum and palladium nanotubes based on genetically engineered elastin-mimetic fusion protein-fiber templates: Synthesis and application in lithium-O₂ batteries

The coupling of proteins with self-assembly properties and proteins that are capable of recognizing and mineralizing specific inorganic species is a promising strategy for the synthesis of nanoscale materials with controllable morphology and functionality. Herein, GPG-AG3 protein fibers with both of these properties were constructed and served as templates for the synthesis of Pt and Pd nanotubes. The protein fibers of assembled GPG-AG3 were more than 10 μm long and had diameters of 20-50 nm. The as-synthesized Pt and Pd nanotubes were composed of dense layers of ∼3-5 nm Pt and Pd nanoparticles. When tested as cathodes in lithium-O₂ batteries, the porous Pt nanotubes showed low charge potentials of 3.8 V, with round-trip efficiencies of about 65% at a current density of 100 mA g^-1.