Gold Nanobipyramid‐Enhanced Hydrogen Sensing with Plasmon Red Shifts Reaching ≈140 nm at 2 vol% Hydrogen Concentration

Abstract Plasmonic sensors that make use of localized surface plasmon resonance provide an excellent platform for hydrogen sensing. In this work, large plasmonic red shifts are obtained on (Au nanobipyramid core)@(Pd shell) bimetallic nanostructures for hydrogen sensing. Au nanobipyramid@Pd nanostructures with different shell thicknesses are synthesized by varying the Pd precursor amount. The Au nanobipyramid@Pd nanostructures with thicker Pd shells are found to exhibit larger responses to hydrogen. The maximal plasmonic red shift reaches 97 nm at 4 vol% hydrogen concentration. The shell morphology of the Au nanobipyramid@Pd nanostructures is further optimized to improve the hydrogen sensing performance. With the optimized nanostructures, the maximal plasmonic red shift is improved to ≈140 nm at 2 vol% hydrogen concentration. Compared with the Au nanobipyramid@Pd nanostructures, Au nanobipyramid/AgPd nanostructures show smaller plasmonic red shifts under the same conditions. The highly enhanced plasmonic shifts and sensitivity to hydrogen make our Au nanobipyramid@Pd nanostructures highly promising for the development of optical hydrogen sensing devices.