NiCo-LDH-Derived 3D Conductive Metal-Organic Framework Heterojunctions for Room-Temperature H2S Sensing with High Selectivity and Sensitivity.

The conjugation of conductive metal-organic frameworks (C-MOFs) into different multicomponent materials to precisely construct heterostructures is a fascinating strategy for enhancing gas sensing performance. Herein, nickel-cobalt layered double hydroxide (NixCo1-x-LDH)/cobalt-hexahydroxytriphenylene (Co-HHTP) heterostructures with tunable Ni/Co molar ratios were successfully fabricated via a two-step hydrothermal and solvothermal method. Structural characterization revealed that Co-HHTP was uniformly grown on the NixCo1-x-LDH surface and the morphology evolved from nanorods to nanoparticles with the increase of Ni molar concentration, forming three-dimensional (3D) architectures with abundant oxygen vacancies and hierarchical porosity. These heterostructures demonstrated outstanding room-temperature H2S sensing performance, with the Ni0.67Co0.33@Co-HHTP sensor achieving the highest response (31.63 to 100 ppm H2S), superior selectivity, and a low detection limit of 30 ppb. The enhanced sensing performance is attributed to the synergistic effects of the porous and dual-channel heterostructure, multiple redox-active sites (Co2+/Co3+ and Ni2+/Ni3+), and favorable electronic band alignment facilitating interfacial charge transfer with H2S. Moreover, the sensors exhibited good reversibility, repeatability, and anti-interference capability under humid conditions. This study highlights the potential of NixCo1-x-LDH@Co-HHTP heterostructures as efficient room-temperature gas sensors and provides insights for designing conductive MOF-based materials with enhanced gas-sensing capabilities.