Engineering Surface Architectures for Improved Durability in III–V Photocathodes

Ben-Naim, Micha, Aldridge, Chase W, Steiner, Myles A, Britto, Reuben J, Nielander, Adam C, King, Laurie A, Deutsch, Todd G, Young, James L and Jaramillo, Thomas F (2022) Engineering Surface Architectures for Improved Durability in III–V Photocathodes. ACS Applied Materials and Interfaces, 14 (18). pp. 20385-20392. ISSN 1944-8244

Preview

Accepted Version Download (738kB) | Preview

Abstract

GaInP2 has shown promise as the wide bandgap top junction in tandem absorber photoelectrochemical (PEC) water splitting devices. Among previously reported dual-junction PEC devices with a GaInP2 top cell, those with the highest performance incorporate an AlInP2 window layer (WL) to reduce surface recombination and a thin GaInP2 capping layer (CL) to protect the WL from corrosion in electrolytes. However, the stability of these III–V systems is limited, and durability continues to be a major challenge broadly in the field of PEC water splitting. This work provides a systematic investigation into the durability of GaInP2 systems, examining the impacts of the window layer and capping layer among single junction pn-GaInP2 photocathodes coated with an MoS2 catalytic and protective layer. The photocathode with both a CL and WL demonstrates the highest PEC performance and longest lifetime, producing a significant current for >125 h. In situ optical imaging and post-test characterization illustrate the progression of macroscopic degradation and chemical state. The surface architecture combining an MoS2 catalyst, CL, and WL can be translated to dual-junction PEC devices with GaInP2 or other III–V top junctions to enable more efficient and stable PEC systems.