PdO/PdO₂ functionalized ZnO : Pd films for lower operating temperature H₂ gas sensing

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Noble metals and their oxide nanoclusters are key for advanced hydrogen (H2) gas sensors.
• Existing methods require improvement for selective and efficient H2 detection.

Purpose of the Study:

• To develop a novel strategy for growing PdO/PdO2 nanoparticles on nanostructured Pd-doped ZnO (ZnO:Pd) films.
• To investigate the H2 gas sensing properties of these functionalized films.
• To explore the potential for selective ppm-level H2 detection.

Main Methods:

• A one-step solution approach followed by thermal annealing at 650 °C was used to synthesize ZnO:Pd films.
• Palladium oxide nanoclusters were functionalized onto the ZnO:Pd film surfaces.
• Morphological, structural, vibrational, optical, chemical, and electronic properties were characterized.

Main Results:

• PdO-functionalized ZnO:Pd films exhibited significantly improved H2 gas sensing properties across a wide operating temperature range (25-200 °C).
• The mixed PdO/PdO2 phases on nanocluster-modified surfaces showed superior selectivity to H2, even at lower operating temperatures (25-150 °C).
• A gas response of ~12.7 to 1000 ppm H2 was achieved at room temperature with no response to other gases.

Conclusions:

• Surface functionalization with PdO/PdO2 mixed phase nanoclusters is more effective than Pd doping alone for selective ZnO-based H2 sensors.
• This approach offers a new pathway for controlled functionalization for precise H2 detection in various atmospheres.
• The developed sensors show potential for detecting highly explosive H2 gas using solid-state devices.