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

Abstract

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 °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 °C and transformed into highly crystalline (orthorhombic) form at 800 °C. The 400 °C annealed Au doped amorphous film showed remarkable blue-shifting (10–11 nm) of the Au surface plasmon resonance (Au-SPR) band in H₂ gas (1 and 0.1% in Ar) at 200 °C with appreciable enhancement of optical density (OD). The shifting as well as enhancement of OD of Au-SPR can be reversibly switched between H₂ 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 H₂ gas at 200–350 °C. The reversible dynamic responses of the transmittance data of Au-SPR in cases of 400 °C annealed films towards H₂ gas and air showed quick response and recovery times at the operating temperature 200 °C. Large Au-SPR shifting in H₂ with significant OD enhancement can be related to the increase of electron transfer on Au NPs facilitating through the embedding amorphous ZrTiO₄ medium.