Surface Engineering of CsPbBr3 Perovskite Photoanodes with Zeolitic Imidazolate Frameworks for Sustainable Oxygen Evolution

Abstract

The aqueous instability of inorganic halide perovskites such as CsPbBr3 remains a critical barrier to their practical utilization in photoelectrochemical water splitting. Here, we employ surface engineering with zeolitic imidazolate frameworks (ZIFs) to simultaneously stabilize CsPbBr3 photoanodes and modulate their interfacial charge-transfer behavior. By systematically comparing Zn-based ZIF-8 and Co-based ZIF-9 overlayers, we distinguish hydrolytic protection from interfacial charge-transfer effects and demonstrate how the metal-node coordination environment governs photoelectrode performance. Although both framework coatings enhance surface hydrophobicity and effectively suppress moisture-induced degradation, they exhibit distinct electronic characteristics. ZIF-8 functions primarily as an insulating passivation layer that suppresses surface recombination but impedes hole transfer because of its high interfacial charge-transfer resistance. In contrast, the Co-based coordination network in ZIF-9 establishes a favorable interfacial heterojunction that lowers the interfacial charge-transfer resistance and facilitates hole extraction toward the oxygen evolution reaction. Consequently, the FTO/TiO2/CsPbBr3/ZIF-9 photoanode delivers a photocurrent density of 2.7 mA cm–2 at 1.23 V vs. RHE, representing an approximately 89% enhancement over the ZIF-8-modified counterpart (1.43 mA cm–2), while retaining more than 75% of its initial photocurrent after 7200 s of continuous illumination. These findings demonstrate that rational surface engineering with MOF overlayers provides a viable strategy for simultaneously enhancing surface protection and interfacial charge transport in perovskite-based photoelectrodes for solar fuel applications.