Engineering the Intrinsic Chirality of Plasmonic Au@Pd Metamaterials for Highly Sensitive Chiroplasmonic Hydrogen Sensing

Metal helicoid nanoparticles with intrinsic 3D chiral structures have emerged as a new class of plasmonic metamaterials with outstanding chiroplasmonic properties. Despite the considerable potential of metal helicoid nanoparticles in chiroplasmonic sensing, their sensing capabilities remain elusive, stressing the need for the rational chirality engineering of helicoid nanoparticles. In this report, Au@Pd helicoid nanoparticles with engineered chiroplasmonic properties and integrated hydrogen sensing capabilities are rationally synthesized. As chiroplasmonic metamaterials, the Au@Pd helicoid nanoparticles exhibit unprecedented sensitivity for hydrogen chiroplasmonic sensing in the visible range. A significant circular dichroism red-shift as large as 206.1 nm can be achieved when they are exposed to hydrogen. Such a high sensitivity outperforms all the plasmonic hydrogen sensors in the visible range. Besides sensitivity, the chiroplasmonic sensing platform shows a good linear range of 1.5-6.0% hydrogen concentration with higher figure of merit, excellent selectivity, and good reusability. To further demonstrate its applicability, this chiroplasmonic hydrogen sensing platform is utilized to investigate hydrogen absorption and desorption kinetics on Pd. This study heralds a new paradigm for plasmonic hydrogen sensing and highlights the tremendous potential of utilizing helicoid nanoparticles as chiroplasmonic sensing metamaterials by chirality engineering. By integrating the chiroplasmonic properties of helicoid Au nanoparticles and the sensing capability of Pd, helicoid Au@Pd nanoparticles with intrinsic chirality are constructed as metamaterials for chiroplasmonic hydrogen sensing. The helicoid Au@Pd nanoparticles display an unprecedented sensitivity exceeding all plasmonic hydrogen sensors in the visible range, as evidenced by substantial circular dichroism red-shift up to 206.1 nm upon hydrogen uptake.image

Automated summary

This report introduces the rational synthesis of Au@Pd helicoid nanoparticles and their chiroplasmonic sensing capabilities for hydrogen. The nanoparticles show unprecedented sensitivity and a good linear range for hydrogen sensing, as well as excellent selectivity and reusability. This study highlights the potential of helicoid nanoparticles as chiroplasmonic sensing metamaterials and presents a new paradigm for plasmonic hydrogen sensing.