Cubic SiC Photoanode Coupling with Ni:FeOOH Oxygen‐Evolution Cocatalyst for Sustainable Photoelectrochemical Water Oxidation

Abstract

As an efficient water oxidation cocatalyst, the Earth‐abundant nickel‐iron oxyhydroxide (Ni:FeOOH) is introduced to coat on the cubic silicon carbide (3C‐SiC) photoanode surface for improving the photoelectrochemical (PEC) water oxidation performance. The FeOOH is prepared on the 3C‐SiC photoanode surface by hydrothermal deposition, followed by a photoassisted electrodeposition of NiOOH. It is shown that the Ni:FeOOH layer is composed of the β‐FeOOH nanorods with a conformal coating of the amorphous NiOOH. Under AM1.5G 100 mW cm−2 illumination, the 3C‐SiC/Ni:FeOOH photoanode exhibits a very low onset potential of 0.2 V versus reversible hydrogen electrode (VRHE) and a high photocurrent density of 1.15 mA cm−2 at 1.23 VRHE, distinctly outperforming the 3C‐SiC and the 3C‐SiC/FeOOH counterparts. Open‐circuit potential and impedance spectroscopy results demonstrate that the nanostructured Ni:FeOOH layer on the 3C‐SiC surface increases the photovoltage and promotes the charge transfer toward the electrolyte, thus significantly improving the PEC water‐splitting performance. These results provide new insights for the development of photoanodes toward efficient solar‐fuel generation.