Optimization of the Composition of PdAuCu Ternary Alloy Nanoparticles for Plasmonic Hydrogen Sensing

Abstract

Alloying is a long-standing central strategy in materials science for the tailoring and optimization of bulk material properties, which more recently has started to find application also in engineered nanomaterials and nanostructures used in, among other, nanoplasmonic hydrogen sensors. Specifically, alloying Pd nanoparticles to form binaries and ternaries with the coinage metals Au and Cu has proven efficient to mitigate hysteresis in the sensor response, improve response and recovery times, boost sensitivity in the low hydrogen concentration sensing range, and reduce the detrimental impact of carbon monoxide poisoning. However, when surveying the corresponding studies, it is clear that there is a trade-off between the sensitivity enhancement and the CO-poisoning resistance effects provided by Au and Cu alloyants, respectively. Therefore, in this work, we systematically screen the impact of the Au and Cu concentration in PdAuCu ternary alloy nanoparticles used for plasmonic hydrogen sensing, to obtain a champion system with maximized sensitivity and CO-poisoning resistance based on an evaluation using the stringent ISO 26142 test protocol. As the main results, we find that the best hysteresis-free and sensitive response combined with deactivation resistance to 500 ppm CO in synthetic air is obtained for the Pd65Au25Cu10ternary alloy system, which also exhibits good long-term stability during operation under severe CO poisoning conditions.