Energy crisis is a broad and complex global topic. Natural resources such as gas and oil are in limited in supply. Development towards renewable resources is one of the most important technologies in the world. Currently, photocatalytic and photoelectrochemical (PEC) water splitting devices under the irradiation of sunlight have received much attention for the production of renewable hydrogen from water. Solar energy conversion and storage through photoelectrolysis of water using semiconductors as both light absorber and energy converter to store solar energy in simple chemical bond, H₂, become highly desirable approaches to solving the energy shortage challenge.

We focus on the effort to develop an efficient Si-based PEC water splitting device. We introduce the surface textured Si heterojunction PEC cell consisting of ultrathin amorphous Si/crystalline Si as efficient and robust photoelectrodes. The solar to hydrogen conversion efficiency has been improved to 13.26%, which is the highest ever reported for Si-based photocathodes. Later on, we design the cascading energy band structure in Si via doping for facilitating carrier separation and novel electrode structures for 360° light harvesting for hydrogen generation with ultrahigh current densities of 61.2 mAcm^-2 and solar-to-hydrogen conversion efficiency of 18.22%. The cells have been further demonstrated with excellent hydrogen production rate. In addition, our method can significantly improve the stability of Si-based solar cells in water to sustain up to 300 hr. These multifunctional designs provide the potential for the future development in the renewable energy market.Dr. Jr-Hau

He is an Associate Professor of Electrical Engineering program at King Abdullah University of Science & Technology (KAUST). He has grants received: > US$ 10M since joining KAUST in July 2014 and garnered over 8700 citations for a body of work consisted of >200 peer reviewed journal articles with 54 of H factor over his career and over 200 presentations in international conferences. His breakthrough researches in 2D materials/electronics and photoelectrochemical water splitting have been highlighted over 50 times by various scientific magazines such as Nature, Nature Materials, IEEE SPECTRUM, EE Times, Semiconductor Today, Materials Today, Chemical & Engineering News, and Nano Today.  He participates actively in activities and services in scientific professional societies. He is a Fellow of RSC and SPIE, and a senior member of IEEE and OSA. 38 postgraduate students (12 Ph.D. and 27 M.S. students) under his supervision completed their degree studies. Visit his web for more information (nanoenergy.kaust.edu.sa).