Nano-spherical Fe₃O₄ modified Ni_xS_y@SiMPs composite materials improve photoelectrochemical performance

More catalytic active sites and fast interfacial charge transfer rates have been shown to be effective strategies to enhance photocatalytic water decomposition. In this work, a microconical textured silicon wafer was constructed by wet chemical etching. Fe₃O₄ nanospheres and Ni_xS_y (NiS and Ni₃S₄ complexes) nanoclusters were prepared by solvothermal method, and Fe₃O₄ and Ni_xS_y were deposited on Si micropyramids (denoted as Fe₃O₄/NiS/Ni₃S₄@SiMPs) by drop-coating methods. Fe₃O₄/NiS/Ni₃S₄@SiMPs exhibited excellent photoelectrochemical properties and good stability at the composite ratio of Fe₃O₄ to Ni_xS_y was 1:5, and the starting potential of the composite was 0.29 V vs.RHE, maximum photohydrogen conversion efficiency was 0.32% (+ 1.21 V vs. RHE), photocurrent density was 0.82 mA cm⁻². Fe₃O₄/NiS/Ni₃S₄@SiMPs exhibited 42 times higher photocurrent density than NixSy@SiMPs with long-term stability was up to 4 h. The results show that Fe₃O₄ significantly improved the photoelectrochemical performance of Ni_xS_y@SiMPs composites, mainly because that Fe₃O₄ nanospheres have high conductivity contributing to photogenerated carrier migration, and the heterojunction between semiconductors with different energy levels (Fe₃O₄, Ni_xS_y, Si) effectively inhibited the recombination of electrons and holes. This work provides directions for the preparation and photoelectrochemical properties of monocrystalline silicon-based supported Ni_xS_y and Fe₃O₄ composites.