(621az) Designing Active and Stable Gallium Indium Phosphide Photocathodes for Solar Hydrogen Production

Authors: 
Britto, R. J., Stanford University
Benck, J. D., Stanford University
Young, J. L., National Renewable Energy Laboratory
Hellstern, T. R., Stanford University
Deutsch, T. G., National Renewable Energy Laboratory
Jaramillo, T. F., Stanford University

Gallium Indium Phosphide (GaInP2) is a promising material for solar hydrogen production. GaInP2 epitaxially grown on GaAs achieved one of the highest solar to hydrogen conversion efficiencies for an integrated photoelectrochemical water splitting device (1,2). The  stability of these devices, however, remains a significant barrier to any feasible industrial or commercial application. In this work, we demonstrate multiple protection strategies to stabilize and improve these devices using sulfide and phosphide nanomaterials. We show that that thin layers of these materials (order of nanometers) can be engineered to provide both corrosion resistance and catalytic activity for GaInP2 photocathodes in highly acidic conditions. In chronoamperometry experiments, our protected devices showed no loss in performance up to 50 hours later and minimal loss in performance even 100 hours later. This represents a substantial improvement in the stability of GaInP2 whose intrinsic stability in acid is on the order of a few minutes. These advancements in stability represent a significant step forward in the feasibility of large scale implementation of solar water splitting devices for sustainable CO2-free hydrogen production.

(1) Khaselev, O.; Turner, J.; Science 1998, 280, 5362.

(2) Ager III, J; Shaner, M.; Walczak, K; Sharp, I; Ardo, S; Energy Environ. Sci. 2015, Accepted Manuscript