Enhanced Proton Conductivity across Protein Biopolymers Mediated by Doped Carbon Nanoparticles

Carbon nanoparticles, known as carbon-dots (C-Dots), are famous for their optoelectronic properties. Here it is shown that C-Dots can also mediate protons, where protein biopolymers are used as the protonic transport matrix. Energy transfer measurements indicate that different doped C-Dots bind to the protein biopolymer in different efficiencies. Electrical impedance measurements reveal enhanced conductance across the protein biopolymer upon C-Dots integration, dependent on the doping type. The enhanced conductivity is attributed to protonic conduction due to the large observed kinetic isotope effect, resulting in one of the highest measured proton conductivity across protein biopolymers. Transistor measurements show that the various doped C-Dots-protein biopolymer exhibit different increase in charge carrier density and in carrier mobility, suggesting different modes of proton transport. The ability of C-Dots to support protonic conduction opens a field of carbon-based protonic nanoparticles and due to the formation simplicity of C-Dots they can be integrated in a variety of protonic devices.