Materials for Efficient Photoelectrochemical Water Splitting: The PEC Working Group

Abstract

The development of durable photoelectrochemical (PEC) water splitting systems with high solar-to-hydrogen (STH) conversion efficiency has been a significant challenge. Critical requirements on semiconductor materials’ band gap, energetics, efficiency, and stability must be satisfied simultaneously. Metal oxides can be stable and earth-abundant, and different tandem cell configurations have been developed to address the band-edges mismatch. More focus is needed on overcoming the efficiency limitations due to absorption, charge mobility, recombination, interfacial kinetics, etc. With suitable band gaps and optoelectronic quality, high efficient PV semiconductors, like III-V, offer alternative pathway to efficient STH conversion by addressing the band edge mismatch using monolithic PEC/PV tandem cell design. Stability, however, remains a key issue. NREL, working with other members of the PEC working group have been investigating the corrosion of III-V materials and interfaces with a goal to develop surface modification methods for mitigating the corrosion issue. Approaches include coatings, ion bombardment, surface nitridation as well as electrolyte treatments. Significant materials challenges remain, and effective usage of resources is needed. The PEC Working Group facilitates progress by bringing together diverse PEC researchers with common interests and goals, promoting collaborative activities, resource sharing, and joint publications.