Pd (II) decorated conductive two-dimensional chromium-pyrazine metal-organic framework for rapid detection of hydrogen

Abstract

The utilization of H 2 for versatile application has demanded highly selective, low cost and rapid hydrogen sensors that are proficient in sensing H 2 near flammability limit. In this report, Cr III Cl 2 (pyrazine) 2 MOF with negatively charged pyrazine linkers in its structure is used for the stabilization of Pd (II) via charge transfer interactions. This material design turned an innocent MOF into selective hydrogen sensor that can respond (through decrease in resistance under dynamic sensing setup) to H 2 in 5–7 s with a detection range of 0.25%–1% H 2 concentration. A correlation of H 2 sensing characteristics and the structure-property relationship is established using density functional theory (DFT) calculations. The calculations suggested that near fermi level in Pd II @CrPy, the bandwidth increases upon interaction with H 2 thereby the phase space for electron delocalization increases leading to better carrier mobility. This new approach not only yields novel sensing properties but also enables limited usage of precious metal to develop cost-effective sensors. • Cr III Cl 2 (pyrazine) 2 MOF with negatively charged pyrazine linkers is used for the stabilization of Pd (II). • Unique metal ion-MOF hybrid design led to the development of rapid (5–7 s) selective chemiresistive H 2 sensor. • Structure-property and sensing correlation is established using density functional theory (DFT) calculations. • High dispersion of Pd (II) enables limited usage of precious metal for cost-effective sensors.