Abstract
BackgroundMicrobes are present in almost every environment on Earth, even in those with extreme environmental conditions such as Antarctica, where rocks may represent the main refuge for life. Lithobiontic communities are composed of microorganisms capable of colonizing rocks and, as it is a not so well studied bacterial community, they may represent a very interesting source of diversity and functional traits with potential for biotechnological applications. In this work we analyzed the ability of Antarctic lithobiontic bacterium to synthesize cadmium sulfide quantum dots (CdS QDs) and their potential application in solar cells.ResultsA basaltic andesite rock sample was collected from Fildes Peninsula, King George Island, Antarctica, and processed in order to isolate lithobiontic bacterial strains. Out of the 11 selected isolates, strain UYP1, identified as Pedobacter, was chosen for further characterization and analysis due to its high cadmium tolerance. A protocol for the biosynthesis of CdS QDs was developed and optimized for this strain. After 20 and 80 min of synthesis, yellow-green and orange-red fluorescent emissions were observed under UV light, respectively. QDs were characterized through spectroscopic techniques, dynamic light scattering analysis, high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy. Nanostructures of 3.07 nm, composed of 51.1% cadmium and 48.9% sulfide were obtained and further used as photosensitizer material in solar cells. These solar cells were able to conduct electrons and displayed an open circuit voltage of 162 mV, a short circuit current density of 0.0110 mA cm−2, and had an efficiency of conversion up to 0.0016%, which is comparable with data previously reported for solar cells sensitized with biologically produced quantum dots.ConclusionsWe report a cheap, rapid and eco-friendly protocol for the production of CdS QDs by an Antarctic lithobiontic bacterium, Pedobacter, a genus that was not previously reported as a quantum dot producer. The application of the biosynthesized QDs as sensitizer material in solar cells was validated.
Highlights
Microbes are present in almost every environment on Earth, even in those with extreme environmen‐ tal conditions such as Antarctica, where rocks may represent the main refuge for life
UYP1 With the aim to select the most promising strain for cadmium sulfide quantum dots (CdS QDs) synthesis from among the collection of Antarctic bacterial lithobionts, we evaluated their ability to tolerate the presence of CdCl2 and to produce H 2S
UYP1 was able to grow in the presence of high concentrations of manganese, iron, zinc, copper and nickel (Additional file 3: Dataset S3) indicating that UYP1 is tolerant to multiple metals
Summary
Microbes are present in almost every environment on Earth, even in those with extreme environmen‐ tal conditions such as Antarctica, where rocks may represent the main refuge for life. Quantum dots sensitized solar cells (QDSSCs) are special devices capable of harvesting sunlight for energy conversion by employing fluorescent semiconductor QDs [13]. Efficiencies of QDSSCs (0.003–10%) [1, 15] are still not as high as silicon solar cells (around 25%) or as solar cells constructed with other semi-conductor materials [16], investigation aiming at improving QDSSCs’ materials, fabrication and efficiency is an active field of research. In this context, the development of photovoltaic technologies based on biologically produced materials is an emerging field with tremendous potential
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