Extraction of nano-silicon with activated carbons simultaneously from rice husk and their synergistic catalytic effect in counter electrodes of dye-sensitized solar cells.

Waqar Ahmad,Luying Li,Zhichun Yang,Wenkui Jing,Jahangeer Khan,Fan Jiang,Yihua Gao,Majid Raissan Al Bahrani,Liang Chu,Nishuang Liu

doi:10.1038/srep39314

Abstract

The extraction of renewable energy resources particularly from earth abundant materials has always been a matter of significance in industrial products. Herein, we report a novel simultaneous extraction of nano-silicon with activated carbons (nano-Si@ACs) from rice husk (RH) by chemical activation method. As-extracted nano-Si@ACs is then used as an energy harvesting materials in counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). The morphology, structure and texture studies confirm the high surface area, abundant active sites and porous structure of nano-Si@ACs. Electrochemical impedance spectroscopy and cyclic voltammetry analyses reveal that the nano-Si@ACs is highly beneficial for fast I3− reduction and superior electrolyte diffusion capability. The nano-Si@ACs CE based DSSC exhibits enhanced power conversion efficiency of (8.01%) in contrast to pristine Pt CE (7.20%). These favorable results highlight the potential application of RH in low-cost, high-efficiency and Pt-free DSSCs.

Highlights

The extraction of renewable energy resources from earth abundant materials has always been a matter of significance in industrial products
In the Thermal gravimetric analysis (TGA) data, the amount of typical weight loss are recorded in three stages: (1) gentle weight loss in the temperature range of ~100–180 °C, which corresponds to the presence of bound water and moisture inside the sample; (2) weight loss in the temperature range of ~180–370 °C, which corresponds to the decomposition of cellulose and lignin of rice husk (RH); and (3) weight loss occurs at above ~360 °C is due to the process of carbonization, which leads to the conversion of cellulose and lignin into gaseous materials and tars[24]
Pt is an attractive candidate for high performance counter electrodes (CEs) of dye-sensitized solar cells (DSSCs) due to its tremendous conductivity and superb electrocatalytic properties

Summary

Introduction

The extraction of renewable energy resources from earth abundant materials has always been a matter of significance in industrial products. Out and vice versa[8,20]; (ii) the individual extractions of ACs or Si from RH need further customization as an active materials for commercial purposes[16,17]; and (iii) more importantly the extraction of silica rather than Si strongly influences the electrochemical performance of photovoltaic and energy storage devices[21]. We report the simultaneous extraction of ACs and Si (instead of silica) from raw RH in a single step via carbonization and magnesiothermic reduction process (as shown in Fig. 1) for DSSCs. Our extraction approach is very simple and beneficial in comparison to previous reported methods[16,20,21,22] due to certain reasons: (i) the obtained nano-Si along with ACs have unique and remarkable structure, which is very promising for DSSCs performance; (ii) the entire procedure is time saving, energy efficient and extendable; and (iii) the whole process does not use any expensive fossil fuel (as carbon source) or bulk Si. Magnesium (Mg) is used here as reducing agent to decrease the reaction temperature for extraction of Si from ores of silica[23]. We believe that enhanced performance is due to unique inter-linked structure of nano-Si with ACs, which may play a key role in future designing of photovoltaic devices

Methods

Results

Conclusion