Inverse surface plasmon resonance based effective hydrogen sensing using nanoscale palladium films

• An inverse surface plasmon resonance (ISPR) based hydrogen sensor is developed using Kretschmann configuration.
• The ISPR peak shift toward a higher angle is realized with increasing H2 concentration.
• The shift was assigned to the formation of PdHx at isolated sites which results in change of local refractive index.
• An appreciable sensitivity is witnessed even for a low H2 concentration (0.1%) and with a response time ∼23 s.

We demonstrate a nanoscale palladium (Pd) based inverse surface plasmon resonance (ISPR) setup for sensing highly inflammable hydrogen (H2) gas. The ISPR setup was employed in Kretschmann configuration to assess the sensitivity of the Pd-films when subjected to H2 gas exposure. With an adequate broadening of the SPR peak maxima, the SPR angle was found to shift from a value of 46.57° to 50.97°, when the concentration of H2 was varied between 0% and 0.9%. The shifting can be attributed to the transient development of isolated PdHx (x < 1) clusters within Pd lattices, resulting in an appreciable change of refractive index locally. The dynamical behaviour of switching on/off states exhibited by a ∼20 nm Pd-film and exposed to 0.1% H2 gas was monitored over several cycles repetitively. The ISPR based H2 sensor, as demonstrated in ambient environment, would find scope to detect low level H2 in industrial and other hazardous areas.

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