Visible light assisted hydrogen generation from complete decomposition of hydrous hydrazine using rhodium modified TiO2 photocatalysts

Abstract

Hydrogen is considered to be an ideal energy carrier, which produces only water when combined with oxygen and thus has no detrimental effect on the environment. While the catalytic decomposition of hydrous hydrazine for the production of hydrogen is well explored, little is known about its photocatalytic decomposition. The present paper describes a highly efficient photochemical methodology for the production of hydrogen through the decomposition of aqueous hydrazine using titanium dioxide nanoparticles modified with a Rh(I) coordinated catechol phosphane ligand (TiO₂–Rh) as a photocatalyst under visible light irradiation. After 12 h of visible light irradiation, the hydrogen yield was 413 μmol g⁻¹ cat with a hydrogen evolution rate of 34.4 μmol g⁻¹ cat h⁻¹. Unmodified TiO₂ nanoparticles offered a hydrogen yield of 83 μmol g⁻¹ cat and a hydrogen evolution rate of only 6.9 μmol g⁻¹ cat h⁻¹. The developed photocatalyst was robust under the experimental conditions and could be efficiently reused for five subsequent runs without any significant change in its activity. The higher stability of the photocatalyst is attributed to the covalent attachment of the Rh complex, whereas the higher activity is believed to be due to the synergistic mechanism that resulted in better electron transfer from the Rh complex to the conduction band of TiO₂.