Au nanoparticles doped ZrTiO4 films and hydrogen gas induced Au-plasmon shifting

Au nanoparticle (NP) doped ZrTiO4 films were prepared on glass substrates using the sol-gel process and characterized. An increase of annealing temperature of the doped film from 400 to 800 degrees C caused growth of the Au NPs from about 7 nm to 17 nm in size, respectively. The matrix ZrTiO4 remained amorphous up to 600 degrees C and transformed into highly crystalline (orthorhombic) form at 800 degrees C. The 400 degrees C annealed Au doped amorphous film showed remarkable blue-shifting (10-11 nm) of the Au surface plasmon resonance (Au-SPR) band in H-2 gas (1 and 0.1% in Ar) at 200 degrees C with appreciable enhancement of optical density (OD). The shifting as well as enhancement of OD of Au-SPR can be reversibly switched between H-2 gas (1-0.1%) and air, and found to be repeatable for several cycles. On the contrary, the Au NP doped crystalline ZrTiO4 film showed less shifting (4-5 nm) of Au-SPR with insignificant difference in OD value after exposure in H-2 gas at 200-350 degrees C. The reversible dynamic responses of the transmittance data of Au-SPR in cases of 400 degrees C annealed films towards H-2 gas and air showed quick response and recovery times at the operating temperature 200 degrees C. Large Au-SPR shifting in H-2 with significant OD enhancement can be related to the increase of electron transfer on Au NPs facilitating through the embedding amorphous ZrTiO4 medium.