Photocatalytic Hydrogen Evolution over Exfoliated Rh-Doped Titanate Nanosheets

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.