Rational design of ternary NiCoFe hydrotalcite nanosheet co-catalysts to enhance the photoelectrochemical performance of α-Fe2O3 photoelectrodes

The reasonable construction of oxygen evolution co-catalysts on semiconductors is an effective means to enhance the photoelectrocatalytic performance of photoelectrodes. In this work, NiCoFe-LDH nanosheets with trimetallic active sites were integrated into α-Fe2O3 photoelectrodes by hydrothermal method and cation exchange reaction method. The NiCoFe-LDH acts as an effective co-catalyst, which significantly reduces the onset potential of the photoelectrode and enhances its photocurrent and stability. The photocurrent density of α-Fe2O3/NiCoFe-LDH composite photoelectrode reaches 0.62 mA/cm2, which is 6.8 and 1.4 times that of pure α-Fe2O3 and α-Fe2O3/NiCo-LDH, respectively and its starting potential is reduced to 0.52 V. At the same time, the co-catalyst with ternary metals provides more active sites on the surface of the photoelectrode, promoting the migration of photogenerated holes to the solution and enhancing the rapid separation of carriers. In addition, the synergistic interaction between multivalent transition metal ions in LDH plays an important role in improving the photoelectrocatalytic performance of the photoelectrodes. The co-catalyst introduced in this paper is expected to enhance the intrinsic photoelectrochemical activity of other semiconductor photoelectrodes and further explore their applications in solar energy conversion.