Amorphous PdRuO as High-Activity Sensitizers for Ultrafast Low-Humidity Sensors

Amorphous noble metals often display excellent sensitization due to their unsaturated atomic coordination and abundant active sites on the surface. In this work, amorphous palladium-ruthenium bimetallic nanoparticles were successfully prepared by lithium doping and incorporated into MOF-303 by using a confinement strategy. Compared with crystalline c-PdRuO@MOF-303, the low-humidity sensor constructed with amorphous a-PdRuO@MOF-303 exhibits higher response values (3600 Hz to 3.39% RH), shorter response/recovery time (9/7 s), low-humidity hysteresis (0.16% RH) and excellent stability. Meanwhile, the a-PdRuO@MOF-303 sensor has been further explored to achieve continuous monitoring of human breathing, cough, and finger humidity, providing broad application prospects for amorphous materials in wearable medical devices and noncontact human-machine interactions. Additionally, the sensitive mechanism was explored by GCMC methods. The simulation results demonstrate that introducing a-PdRuO into the pores of MOF-303 leads to significant enhancement in adsorption properties. This improvement is not only due tothe increase of active sites provided by a-PdRuO but also the substantial rise in adsorption energy for the hydrophilic pocket of MOF-303. The adsorption energy increases from -25.70 to -31.56 kJ/mol, highlighting that the abundant active sites of the a-PdRuO work in synergy with the hydrophilic pocket of MOF-303. This synergy enables the adsorption and activation of more water molecules, effectively enhancing the overall adsorption capacity and performance of the MOF-303.