Research Highlights
High Density n-Si/n-TiO2 Core/Shell Nanowire Arrays with Enhanced Photoactivity
Peidong Yang and co-workers:
In the Helios Solar Energy Research Center we aim to develop low-cost inorganic materials that can efficiently perform solar water splitting as photoelectrolysis of water into hydrogen and oxygen, to enable the production of clean energy. We investigate the Si/TiO2 nanowire heterostructures to determine their potential for the photooxidation of water. We observed that highly dense Si/TiO2 core/shell nanowire arrays enhanced the photocurrent by 2.5 times compared to a traditional planar Si/TiO2 structure due to their low reflectance and high surface area.
We also observed a further increase of the photocurrent by using n-Si/n-TiO2 heterojunctions because n/n junctions enhance the charge separation and minimize recombination. The n/n heterojunction is a promising structure for solar water splitting since the photovoltage at the junction can compensate the lower energy level of the conduction band of the shell semiconductor. Also, the n/n heterojunction could potentially increase the efficiency of the photovoltaic cell due to a higher open circuit voltage and higher photocurrent.
