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

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 CsPbBr3‐based photoanode that reaches a low onset potential of +0.4 VRHE and 8 mA cm−2 photocurrent density at +1.23 VRHE for water oxidation, close to the radiative efficiency limit of CsPbBr3. 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 CsPbBr3. Devices with >1 cm2 area, and low‐temperature processing demonstrate the potential for low capital cost, stable, and scalable perovskite photoanodes. A critical challenge for the application of perovskite photoelectrodes for solar fuels and feedstock generation is to overcome their instability in aqueous media and the use of expensive materials. In this work, a CsPbBr3 photoanode is presented that contains solely earth‐abundant materials and reaches over 100 h operational stability, which can be easily extended to weeks.