Using colloidal lithography, a series of inverted long-range ordered crystals (i-LROCs) of Pd honeycombs were fabricated on quartz crystal microbalance (QCM) sensors. The structures formed provided the required platform for the proceeding galvanic replacement reaction (GR) process to generate seamless Au nanoparticle deposits throughout the i-LROC. The results showed that controlling the dimensions of the pores in the developed Pd i-LROCs is important in the formation of gold deposition sites on the uniform structures through the GR reaction process. The developed Pd/Au i-LROC deposited sensors showed significant enhancement in the sensitivity toward Hg-0 vapor when compared to pure Pd structures, with limit of detection improving from 60.0 to 13.7 mu g/m(3), respectively. Furthermore, a significant improvement in the modified sensor's selectivity toward Hg in the presence of other industrial related gas species was observed which is attributed to the addition of Au to the Pd structures through GR reaction. (C) 2019 Published by Elsevier Inc.