PhD Dissertation Defense

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PhD Defense: Highly efficient photoleletrochemical water splitting by optical, electrical and catalysis concurrent management

Start Date: February 11, 2019
End Date: February 11, 2019

By Hui-Chun Fu, PhD Candidate of Professor Jr-Hau He (KAUST)‚Äč

One way of harnessing and storing our most abundant and renewable energy source, sunlight, is by utilizing it to split water into hydrogen and oxygen for the generation of hydrogen as a storable form of fuel. Si, the most investigated material for solar-to-hydrogen technology has great potential as the single photoelectrode. While some success has been achieved in Si-Based photoelectrochemical (PEC) systems, they suffer from low efficiency and short longevity. Moreover, in order for hydrogen to be commercially viable, the existing challenges of electrical, optical, and catalysis management must be addressed concurrently. Herein, we work on the simultaneous improvement in light harvesting, charge carrier separation/transfer, and catalysis management of Si-based photocathodes, achieving best-in-class efficiency with stable electrochemical performance. By decoupling the light harvesting side from the electrocatalytic surface we nullify parasitic light absorption. We developed a Si bifacial (SiBF) PEC photocathode to absorb light on both sides of PEC devices, which exhibits a current density of 39.01 mA/cm2. Unlike conventional monofacial PEC cells, our bifacial design demonstrates excellent omnidirectional light harvesting capability. Futhermore, we implement another novel photon decoupling scheme by fabricating back buried junction photoelectrochemical (BBJ-PEC) cells. This scheme enables maximum light-harvesting without any metal contact, which prevents the shading effect, while the electrochemical reaction occurs on the bottom side of the PEC cell. The resultant single-junction BBJ-PEC cell achieves a current density of 41.76 mA/cm2 for hydrogen evolution, the best reported to date. By connecting the three BBJ-PEC cells in series, we have also realized unassisted photoelectrochemical water splitting. The efficient PEC cell design described herein demonstrates promising performance, taking us a step closer to real-world solar-to-hydrogen production.
 

More Information:

For more info contact: Hui-Chun Fu: email: huichun.fu@kaust.edu.sa
 
Date: Monday 11th Feb 2019
Time:10:30 AM - 11:30 AM
Location: Building 3, Room 5209
Refreshments will be available