Synergy of W doping and oxygen vacancy engineering on d-band center modulation for enhanced gas sensing performance

Abstract

The development of semiconductor metal oxide (SMO)-based gas sensors is impeded by the limited availability of active sites and insufficient gas mass transfer. To overcome this challenge, we developed W-doped porous/hollow NiCo₂O₄ (NiCoW) nanostructures with oxygen vacancy construction. The porous nanostructure of NiCoW promotes gas mass transfer on the surface and within the interior of the material. By harnessing the optimized electronic structure and heightened catalytic activity brought forth by W doping, the NiCoW structure exhibits effective adsorption of and activation by target gas molecules. Consequently, the 20% W-doped NiCoW-based sensor shows excellent gas sensing performance for 10 ppm TEA, featuring outstanding response value (S = 26.8), prolonged stability (over 30 days), exceptional repeatability, and superior selectivity. In particular, TEA molecules can be detected in the ppb range using the sensor. The improvement in gas sensing performance could be attributed to the creation of oxygen vacancy active sites through W doping, as confirmed by DFT simulations. Furthermore, DFT simulations reveal that the generation of oxygen vacancies induces an upward shift in the d-band center, thus leading to improved interfacial electron transport and gas adsorption.