Bio-industrial Waste Silk Fibroin Protein and Carbon Nanotube-Induced Carbonized Growth of One-Dimensional ZnO-based Bio-nanosheets and their Enhanced Optoelectronic Properties.

High performance UV/Visible photodetectors are successfully fabricated from ZnO/fibroin protein-carbon nanotube (ZFP ) composites using a simple hydrothermal method. The as-fabricated ZnO nanorods (ZnO NRs) and ZFP nanostructures were measured under different light illuminations. The measurements showed the UV-light photoresponse of the as-fabricated ZFP nanostructures (55,555) to be approximately 26454 % higher than that of the as-prepared ZnO NRs (210). This photodetector can sense photons with energies considerably smaller (2.75 eV) than the band gap of ZnO (3.22 eV). It was observed that the finest distribution of fibroin and CNT into 1D ZnO resulted in rapid electron transportation and hole recombination via carbon/nitrogen dopants from the ZFP . Carbon dopants create new energy levels on the conduction band of the ZFP , which reduces the barrier height to allow for charge carrier transportation under light illumination. Moreover, the nitrogen dopants increase the adsorptivity and amount of oxygen vacancies in the ZFP so that it exhibits fast response/recovery times both in the dark and under light illumination. The selectivity of UV light among the other types of illumination can be ascribed to the deep-level energy traps (E ) of the ZFP . These significant features of ZFP lead to the excellent optical properties and creation of new pathways for the production of low-cost semiconductors and bio-waste protein based UV/Visible photodetectors.