5,10,15,20-Tetrakis(4-carboxylphenyl)porphyrin modified nickel-cobalt layer double hydroxide nanosheets as enhanced photoelectrocatalysts for methanol oxidation under visible-light.

The development of low-cost noble metal-free and high-active electrocatalysts for methanol electrooxidation is highly worthwhile but remains a challenge. In this paper, 5, 10, 15, 20-tetrakis(4-carboxylphenyl)porphyrin (HTCPP) modified nickel-cobalt layer double hydroxides nanosheets (NiCo-LDH) were prepared by one-pot hydrothermal method and characterized by the powder X-ray diffraction (XRD), the scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS), etc. HTCPP/NiCo-LDH was demonstrated as superior a photoelectrocatalyst towards methanol oxidation in the alkaline media. Due to the introduction of HTCPP photosensitizer, HTCPP/NiCo-LDH exhibits the outstanding photoeletrocatalytic activity toward methanol oxidation under the visible-light irradiation. The great enhancement in the photoelectrocatalytic activity are attributed to high exposed surface active sites, efficient widen adsorption wavelength of HTCPP in visible region, as well as efficient electron transfer between the electrode surface and the active sites. The HTCPP/NiCo-LDH nanosheets show mass activity of 246.6 mA mg and specific activity of 34.9 mA cm for methanol oxidation under visible-light, which are 2.32 times higher than that of NiCo-LDH at the same conditions. The developing catalytic activity of HTCPP/NiCo-LDH for methanol oxidation are attributed to the synergistic effect of HTCPP and NiCo-LDH. This study may offer new ideas for developing highly effective noble metal-free catalysts for the application in methanol oxidation.