|About this Abstract
||2010 Electronic Materials Conference
||TMS 2010 Electronic Materials Conference
||P6, Branched ZnO/Si Nanowire Heterostructure Based Photoelectrochemical Cell for Efficient Water Splitting
||Ke Sun, Banu Khaleda, Yi Jing, Namsoek Park, Deli Wang
|On-Site Speaker (Planned)
Design and synthesis of nanoscale heterostructures has attracted significant attentions in recent years because of their unique properties, diverse functionalities, and potential applications in photovoltaics and photocatalytics . Various nanowire-based heterostructures, such as axial, radial/core-shell, and branched structure, have been developed and studied, due to their prominent tunable functionalities and greatly enhanced surface reactivity. These types of structure have helped scientists in hydrogen generation from water splitting. In principle, nanoheterostructure is working as a photoelectrochemical (PEC) anode/cathode generating electron/hole pairs from incident photons and then generated electrons reduce hydrogen ions. In this work, we report our research effort on developing efficient PEC cells for water splitting based on a branched n-ZnO/p-Si nanowire heterostructure from a cost-efficient and robust solution-phase integration process. Wafer-scale and highly dense vertical arrays of Si nanowire arrays were prepared using metal-assisted electroless etching . SEM and TEM investigations show the vertical alignment, smooth surface of etched Si nanowires and large variations in diameter (average around 70nm). ZnO nanowires, intrinsically n-type, were then synthesized on the ZnO seeded Si nanowire arrays using hydrothermal method. SEM studies show the growth of ZnO nanowires in between Si nanowires to form branched heterostructures with average diameter of 50nm and average length of 250nm. The ZnO/Si n/p heteorstructures is then immersed in neutral electrolytes (pH=7) due to the less stability of ZnO in acidic or basic solution  and the photoelectrochemical production of hydrogen were tested under solar illustration (AM 1.5G) and the overall hydrogen production efficiency of the PEC cell is evaluated. The branched nanowire configuration enables low cost direct integration of heterogenerous nanomaterials with reduced defect density for high efficiency hydrogen generation.