Scalable All‐Inorganic Halide Perovskite Photoanodes with >100 h Operational Stability Containing Earth‐Abundant Materials

Abstract The application of halide perovskites in the photoelectrochemical generation of solar fuels and feedstocks is hindered by the instability of perovskites in aqueous electrolytes and the use of expensive electrode and catalyst materials, particularly in photoanodes driving kinetically slow water oxidation. Here, solely earth‐abundant materials are incorporated to fabricate a CsPbBr ₃ ‐based photoanode that reaches a low onset potential of +0.4 V _RHE and 8 mA cm ⁻² photocurrent density at +1.23 V _RHE for water oxidation, close to the radiative efficiency limit of CsPbBr ₃ . This photoanode retains 100% of its stabilized photocurrent density for more than 100 h of operation by replacing once the inexpensive graphite sheet upon signs of deterioration. The improved performance is due to an efficiently electrodeposited NiFeOOH catalyst on a protective self‐adhesive graphite sheet, and enhanced charge transfer achieved by phase engineering of CsPbBr ₃ . Devices with >1 cm ² area, and low‐temperature processing demonstrate the potential for low capital cost, stable, and scalable perovskite photoanodes.