Phosphating 2D CoAl LDH anchored on 3D self-assembled NiTiO3 hollow rods for efficient hydrogen evolution

Abstract

Two photo-active materials with opposite surface potentials, NiTiO₃ with a negative potential and CoAl LDH with a positive potential, have been rationally integrated into two-dimensional (2D) active plane phosphated-CoAl LDH with rich active sites and three-dimensional (3D) hollow NiTiO₃ rods with more negative zeta potential. The delicate architecture can efficiently accelerate the separation and migration of photo-excited electrons, make the surface potential more negative, enhance thermodynamic H₂ evolution reaction, and offer rich active planes for photo-catalytic redox reactions. Based on these highlighted photo-catalytic benefits, the optimal composite exhibits more prominent photo-catalytic hydrogen evolution performance compared with NiTiO₃ or CoAl LDH materials alone under visible irradiation. In detail, the stereoscopic catalyst, constructed by phosphating CoAl LDH layers anchored on NiTiO₃ hollow rods, exhibits a hydrogen evolution activity of about 594 μmol 5 h⁻¹, which is 11.6 times and 14.8 times that of CoAl LDH (51 μmol 5 h⁻¹) and NiTiO₃ (40 μmol 5 h⁻¹) alone, respectively. Also, the density functional theory results reveal the good conductivity, which is beneficial for charge migration in the hybrid sample. The results from the thoroughly conducted characterization studies such as TEM, SEM, XPS, XRD, UV-vis DRS, transient photocurrent, and FTIR spectroscopy have been well researched and they are in good agreement with each other.