Ag nanoparticle decorated molybdenum oxide structures: growth, characterization, DFT studies and their application to enhanced field emission.

We report a simple single step growth of α-MoO structures and energetically suitable site specific Ag nanoparticle (NP) decorated α-MoO structures on varied substrates, having almost similar morphologies and oxygen vacancies. We elucidate possible growth mechanisms in light of experimental findings and density functional theory (DFT) calculations. We experimentally establish and verified by DFT calculations that the MoO(010) surface is a weakly interacting and stable surface compared to other orientations. From DFT study, the binding energy is found to be higher for (100) and (001) surfaces (∼-0.98 eV), compared to the (010) surface (∼-0.15 eV) and thus it is likely that Ag NP formation is not favorable on the MoO(010) surface. The Ag decorated MoO (Ag-MoO) nanostructured sample shows enhanced field emission properties with an approimately 2.1 times lower turn-on voltage of 1.67 V μm and one order higher field enhancement factor (β) of 8.6 × 10 compared to the MoO sample without Ag incorporation. From Kelvin probe force microscopy measurements, the average local work function (Φ) is found to be approximately 0.47 eV smaller for the Ag-MoO sample (∼5.70 ± 0.05 eV) compared to the MoO sample (∼6.17 ± 0.05 eV) and the reduction in Φ can be attributed to the shifting Fermi level of MoO toward vacuum via electron injection from Ag NPs to MoO. The presence of oxygen vacancies together with Ag NPs lead to the highest β and lowest turn-on field among the reported values under the MoO emitter category.