A cost-effective birnessite-silicon solar cell hybrid system with enhanced performance for dye decolorization

A cost-effective and simple configuration of birnessite-silicon solar cell (Bir-SSC) hybrid system is reported in this study. Birnessite, with a band gap of 2.1 eV as determined by UV-vis spectroscopy, was electrochemically deposited on a fluorine-doped tin oxide (FTO) for usage as the anode. It was thoroughly characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy, and its prompt response to visible light was further tested by linear sweep voltammetry (LSV). When birnessite electrode was connected with a silicon solar cell in a hybrid system, a remarkably enhanced methyl orange (MO) decolorization from 47.1% (with a bare SSC) to 95.8% was observed. The results indicated the synergistic effects of photoelectrochemical and electrochemical reactions in the hybrid system. In addition, the electron utilization efficiency was 15.29% and 8.54% with and without light irradiation on birnessite respectively. When applied with three different rated voltage SSC, 2.0 V SSC showed the best fit in the hybrid system. Cycling experiments exhibited the stable performance of birnessite electrode, where the MO color removal ratio in ten cycles remained stable at 90.1 +/- 2.5%, which is close to the first cycle (95.8%). The hybrid system possesses the merits of cost-effectiveness, low-power consumption, and green fabrication strategy, which exbihits promising potential in solar energy utilization and wastewater treatment.