Au@Pt/Pd Core-Shell Nanoparticle Arrays: Dual-Modal Plasmonic Hydrogen Sensor with Tunable Reversible/Irreversible...

Area of Science:

• Nanomaterials Science
• Chemical Sensing
• Plasmonics

Background:

• Developing optical hydrogen sensors with dual detection modes (reversible and irreversible) is a significant challenge.
• Existing sensors often lack the ability to signal both low-concentration reversibility and high-concentration irreversibility on a single platform.

Purpose of the Study:

• To engineer a single platform for optical hydrogen sensing with both reversible detection of low H2 concentrations and irreversible signaling of high H2 concentrations.
• To investigate the mechanisms behind dual-modal sensing in nanoparticle arrays.

Main Methods:

• Fabrication of gold-platinum (Au@Pt) core-shell nanoparticle arrays (NAs).
• Investigation of optical properties (extinction peak shifts, intensity changes) under varying hydrogen (H2) concentrations.
• Tuning the critical transition concentration (CTC) by alloying the platinum shell with palladium (Pd).

Main Results:

• Au@Pt NAs exhibited reversible blue shifts (<10% H2) due to dielectric changes and irreversible aggregation (>10% H2) causing color change and intensity decrease.
• The critical transition concentration (CTC) was tunable by alloying Pt with Pd, lowering it to 1% H2 with 25% Pd.
• Higher Pd ratios led to a fully irreversible response.

Conclusions:

• Au@Pt NAs function as a dual-modal plasmonic hydrogen sensor by integrating reversible dielectric modulation and irreversible aggregation mechanisms.
• The sensor's sensitivity is systematically tunable via Pd alloying, broadening its applicability.
• This work introduces a new class of Pt-based plasmonic sensors with dual-mode functionality for diverse hydrogen sensing scenarios.