Stabilization of Silicon Photoanode By Hafnium Zirconium Oxide Interlayer for Efficient Solar Water Oxidation

Photoelectrochemical devices, which convert solar energy into sustainable hydrogen, are promising for carbon neutralization. The prerequisites for the photoelectrode materials are absorbing a wide range of the solar spectrum, cost-effectiveness, long carrier lifetime, and so on. Silicon, which has a bandgap of 1.12 eV, has been of prime interest because of its excellent charge carrier mobility, earth abundance, and high crystallinity. However, instability in the electrolytes, poor catalytic activity, and negative valence band position hampers its application. The design of metal-insulator-semiconductor (MIS) structures is a promising strategy for boosting catalytic surface reactions with high stability. Herein, we report the interface engineering of MIS photoanodes with enhanced stability for water oxidation. First, we investigate the effect of poling direction of hafnium zirconium oxide (HZO) with a few-nm thickness as a surface passivation layer. Then, additional Ni/NiFe layered double hydroxide (LDH) catalysts are introduced to accelerate surface catalytic reactions. Harmonizing the HZO interlayer and Ni/NiFe LDH on silicon performs with a high current density of 26.6 mA cm -2 at 1.23 V vs. reversible hydrogen electrode with stability. This study demonstrates the rational design of MIS structure and manipulating hierarchical photoanodes' interface to boost stability and charge carrier kinetics.