Abstract
Dye-sensitized solar cells (DSSCs), a powerful system to convert solar energy into electrical energy, suffer from the high cost of the Pt counter electrode and photosensitizer. In this study, the dual application of waste grape skin is realized by employing the grape skin and its extract as the carbon source of the carbon-based counter electrode and photosensitizer, respectively. The ultraviolet–visible absorption and Fourier transform infrared spectroscopy verify the strong binding between the dye molecules (anthocyanins) in the extract and the TiO2 nanostructure on the photoanode, contributing to a high open-circuit voltage (VOC) value of 0.48 V for the assembled DSSC device. Moreover, the waste grape skin was subjected to pyrolysis and KOH activation and the resultant KOH-activated grape skin-derived carbon (KA-GSDC) possesses a large surface area (620.79 m2 g−1) and hierarchical porous structure, leading to a high short circuit current density (JSC) value of 1.52 mA cm−2. Additionally, the electrochemical impedance spectroscopy reveals the efficient electron transfer between the electrocatalyst and the redox couples and the slow recombination of electrolytic cations and the photo-induced electrons in the conduction band of TiO2. These merits endow the DSSC with a high photovoltaic efficiency of 0.48%, which is 33% higher than that of a common Pt-based DSSC (0.36%). The efficiency is also competitive, compared with some congeneric DSSCs based on other natural dyes and Pt counter electrode. The result confirms the feasibility of achieving the high-value application of waste grape skin in DSSCs.
Highlights
The energy crisis and environmental problems caused by the massive consumption of fossil fuels have greatly stimulated people’s enthusiasm for clean sustainable energy resources
The photovoltaic efficiency of the grape skin extract-sensitized solar cell device using the inexpensive KOH-activated grape skin-derived carbon (KA-Grape Skin-Derived Carbon (GSDC)) as the counter electrode is comparable to or even higher than the data of these dye-sensitized solar cells (DSSCs) based on other types of natural dyes and Pt counter electrode (0.05–0.47%)
The dual application of waste grape skin is realized by using the grape skin and its extract as the carbon source of the counter electrode and the photosensitizer, respectively
Summary
The energy crisis and environmental problems caused by the massive consumption of fossil fuels have greatly stimulated people’s enthusiasm for clean sustainable energy resources. Nanomaterials 2022, 12, 563 below [12,13]: (1) the dye molecule located above the edge of the conduction band (CB) of semiconductor nanoparticles (such as TiO2) absorbs photons (hν) and transfers to the electron excited state D* (Equation (1)) and injects an electron into the CB (Equation (2)); above the edge of the conduction band (CB) of semiconductor nanoparticles (such as TiO ). Are key reasons that hinder electron collection efficiency by light injection; (3) the two (back electron transfer) and Equation (7) (redox pair electron capture of CB) show two processes compete with the oxidation of iodide (Equation (4)) and reduce the cell’s percharge recombination processes, which are key reasons that hinder electron collection formance.
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