Photocatalytic Hydrogen Evolution over Exfoliated Rh-Doped Titanate Nanosheets

[Image: see text] Various amounts of Rh-doped titanate nanosheets (Ti(3)NS:Rh(x), where x is doped amount) were prepared to develop a new nanostructured photocatalyst based on metal oxide compounds that can split water to produce H(2) under sunlight. Ti(3)NS:Rh(x) was obtained by acid exchange, intercalation, and exfoliation of Rh-doped layered sodium titanate compound (Na(2)Ti(3–x)Rh(x)O(7)). A new energy gap was found in the diffuse reflection spectrum of the Ti(3)NS:Rh(x) colloidal suspension solution; this new energy gap corresponds to electrons in the 4d level of Rh(3+) or Rh(4+), which are doped in the Ti(4+) site. A photocatalyst activity of Ti(3)NS:Rh(x) for H(2) evolution in water with triethylamine (TEA) as an electron donor was investigated. The appropriate amount of Rh doping can improve the photocatalytic activity of Ti(3)NS for H(2) evolution from water using triethylamine (TEA) as a sacrifice agent. The reason was related to the rich state of Rh(3+) or Rh(4+) doped in the Ti(4+) site of Ti(3)NS. Doping Rh 1 mol % of Ti, Ti(3)NS:Rh(0.03) shows the H(2) evolution rates up to 1040 nmol/h, which is about 25 times larger than that of nondoped Ti(3)NS under UV irradiation (>220 nm) and 302 nmol/h under near-UV irradiation (>340 nm). These results show that the development of new nanostructured photocatalyst based on Rh-doped titanate compounds that can produce H(2) under near-UV irradiation present in sunlight was a success.