Study of Copper Ferrite as a Novel Photocathode for Water Reduction: Improving Its Photoactivity by Electrochemical Pretreatment

Abstract Studies on water‐splitting p‐type oxide electrodes based on nontoxic earth‐abundant elements are scarce. Herein, the behavior of electrodes composed of CuFe 2 O 4 nanoparticles 30 nm in size is presented. The as‐prepared CuFe 2 O 4 nanoporous electrodes exhibit small anodic photocurrents in 0.1 m NaOH. However, an electrochemical pretreatment consisting in the application of sufficiently positive potentials leads to p‐type behavior with a photocurrent onset as high as 1.1 V versus the reversible hydrogen electrode, which is among the most positive values reported for an oxide absorbing visible light (band gap of 2.1 eV). This photocurrent is partly due to H 2 evolution, but there are also signs of photoreduction of the material. Although the photocurrents are modest, these results point to the possibility of using CuFe 2 O 4 as a photocathode material in water‐splitting devices. Furthermore, the strategy employed for the enhancement in the CuFe 2 O 4 photoactivity could be extended to other photocathode materials.