Conversion of Rice Husk into Silicon Carbide Nanowires for Photocatalytic and Electrocatalytic Applications

Silicon carbide (SiC) nanowires with rhombohedral structure, length of longer than 20 μm and diameter of less than 100 nm, respectively were prepared under Ar atmosphere at 1250 ℃ for 180 min using rice husk as the raw materials. The band gap of the rice husk-derived SiC nanowires (RH-SiC) is 2.05 eV and RH-SiC can be utilized as visible-light photocatalysts for organic pollutants removal. For rhodamine B (RhB) and methylene blue (MB) removal using 25 mg RH-SiC, 20 mL RhB and MB solution (0.01 g·L^-1) can be removed with solar light irradiation for 40 min and 55 min, respectively. RH-SiC can also be utilized as efficient electrode materials for simultaneous detection of Hg²⁺, Pb²⁺ and Cd²⁺. Three stripping peaks are located at - 0.74 V, - 0.54 V, and + 0.71 V for 1 mM Hg²⁺, 0.1 mM Pb²⁺ and 1 mM Cd²⁺, respectively in 0.1 M KCl solution using the RH-SiC-modified electrode. Solution pH value of 7, deposition potential of - 1.5 V, deposition time of 120 s and standing time of 60 s are the optimal operating parameters. The detection range and limit of detection are 0.63 nM and 0.01-1000 µM, 0.45 nM and 0.001-100 µM, 0.87 nM and 0.01-1000 µM for simultaneously detection of Hg²⁺, Pb²⁺ and Cd²⁺. The RH-SiC-modified electrode exhibits good selectivity, reproducibility, stability and practical applicability for efficiently detecting Hg²⁺, Pb²⁺ and Cd²⁺.