One step large-scale preparation of silicon-based efficient solar vapor generators†

In this work, the fabrication of the material for solar vapor generation using porous silicon treated by electrochemical etching, metal-assisted chemical etching, and electrochemical metal-assisted etching is reported. The proposed method does not require high-cost equipment and permits the production of centimeter-sized samples within minutes. Morphologies of the samples have been studied by scanning electron microscopy and X-ray diffraction spectroscopy, and the distribution of the impurities has been observed by dispersive X-ray analysis. First-principles modeling has been used to simulate the effect of nickel dopants on the electronic structure of the silicon matrix. Measurements of Raman spectra demonstrate a colossal increase in the signal intensity for all samples. The estimated vaporization performance of studied samples varies from 4.4 kg m⁻² h⁻¹ up to 5.2 kg m⁻² h⁻¹, more than four times larger than previously reported for silicon-based SVG systems prepared by more sophisticated techniques. The results of the measurements demonstrate the tiny influence of low-concentration doping on vaporization performance. On the contrary, higher porosity and more significant numbers of defects increase the vaporizing efficiency of studied samples.