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Title: CaCd 2 P 2 : A Visible‐Light Absorbing Zintl Phosphide Stable Under Photoelectrochemical Water Oxidation
ABSTRACT A key bottleneck to solar fuels is the absence of stable and strongly absorbing photoelectrode materials for the oxygen evolution reaction (OER). Modern approaches generally trade off between stable but weakly absorbing materials, such as wide bandgap oxides, or strongly absorbing materials that rely on encapsulation for stability and are weakly catalytic, such as the III‐V family of semiconductors. Of interest are materials like transition metal phosphides, such as FeP2, that are known to undergo beneficial in situ surface transformations in the oxidative environment of OER, though stability has remained a primary hurdle. Here, we report on CaCd2P2, a Zintl phase visible‐light absorber with favorable 1.6 eV bandgap, that we identified using high‐throughput computational screening. Using a combination of photoelectrochemical measurements, microscopy, and spectroscopy, we show that CaCd2P2undergoes a light‐stabilized surface transformation that renders it stable under alkaline OER conditions. We also show that the well known OER catalyst CoPi can act as a stable co‐catalyst in synergy with the modified in situ CaCd2P2surface. The light‐induced stabilizing transformation that CaCd2P2undergoes is in sharp contrast to the photocorrosion commonly observed in visible light‐absorbing photoelectrodes. The broader AM2P2family of Zintl phases offers a significant opportunity to explore stabilizing interface chemistry and re‐design the manner in which low‐bandgap semiconductors are used for photoelectrochemical energy conversion.  more » « less
Award ID(s):
2011967
PAR ID:
10682604
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley
Date Published:
Journal Name:
Advanced Energy Materials
Volume:
16
Issue:
10
ISSN:
1614-6832
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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