Highly Stable Au/Hexaniobate Nanocomposite Prepared by a Green Intercalation Method for Photoinduced H2 Evolution Applications

Highly stable Au/K4-xHxNb6O17 nanocomposites were prepared by employing photochemically made Au nanoparticles surrounded by branched poly(ethyleneimine) (PEI) and successfully applied as photocatalysts for H-2 evolution. The nanocomposites were prepared in a single step by the pH control of the surface charges of the respective materials. The resulting nanocomposites with different Au loadings were fully characterized and compared with their counterparts in which plain Au nanoparticles were photodeposited on the hexaniobate. Vibrational and X-ray photoelectron spectroscopy evidenced that the Au(PEI) nanoparticles are strongly adsorbed onto the hexaniobate and cause substantial changes in the electronic density of their surface atoms. Following band gap excitation, electrons are efficiently transferred to the Au(PEI) nanoparticles as evidenced by electron paramagnetic resonance spectroscopy. The nanocomposites are able to promote H-2 evolution from methanol/water mixtures under ultraviolet-visible (UV-vis) irradiation with rates up to 294 +/- 20 mu mol h(-1) g(-1) for the 2% wt. Au(PEI)/hexaniobate, corresponding to an apparent quantum yield of 1.1 +/- 0.1%. This performance is similar to that obtained for the photodeposited nanocomposite with analogous Au loading, but the new composite was at least three times more stable under long-term irradiation. The photocatalytic behavior of the Au(PEI)/hexaniobate was rationalized based on detailed spectroscopic and morphologic characterizations, providing new insights for the development of robust photocatalysts based on two-dimensional (2D) metal oxide semiconductors.

Automated summary

Highly stable Au/K4-xHxNb6O17 nanocomposites were prepared and successfully applied as photocatalysts for H-2 evolution. Different Au loadings were studied and compared with plain Au nanoparticles. The study showed that Au(PEI) nanoparticles could effectively promote the H-2 evolution reaction.