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Molybdenum oxide films offer a rich variety of properties for diverse applications, but exclusive synthesis of desired phases is a major challenge. Here, we demonstrate that oxygen flow ratio fO2 = [O2]/[Ar + O2] is crucial not only for phase selection of non-layered monoclinic MoO2 and layered orthorhombic α-MoO3 but also for controlling grain size and preferred orientation. Both mica and sapphire support exclusive MoO2 formation for 0.15 ≤ fO2 ≤ 0.25 at deposition temperatures Tdep = 400 and 500 °C, while α-MoO3 forms only at Tdep = 400 °C for 0.35 ≤ fO2 ≤ 0.5. Within the fO2 windows favoring each phase, high fO2 fosters large grains with out-of-plane 0k0 texture, except for MoO2 on c-sapphire at Tdep = 500 °C, where no fO2-texture correlation is discernible. These findings provide a framework for rational synthesis of single-phase monoclinic MoO2 and orthorhombic MoO3 with control over texture and microstructure to access desired properties. 

CrN-based alloy thin films are of interest as thermoelectric materials for energy harvesting. Ab initio calculations show that dilute alloying of CrN with 3 at. % W substituting Cr induce flat electronic bands and push the Fermi level EF into the conduction band while retaining dispersive Cr 3d bands. These features are conducive for both high electrical conductivity σ and high Seebeck coefficient α and, hence, a high thermoelectric power factor α2σ. To investigate this possibility, epitaxial CrWxNz films were grown on c-sapphire by dc-magnetron sputtering. However, even films with the lowest W content (x = 0.03) in our study contained metallic h-Cr2N, which is not conducive for a high α. Nevertheless, the films exhibit a sizeable power factor of α2σ ∼ 4.7 × 10−4 W m−1 K−2 due to high σ ∼ 700 S cm−1, and a moderate α ∼ − 25 μV/K. Increasing h-Cr2N fractions in the 0.03 < x ≤ 0.19 range monotonically increases σ, but severely diminishes α leading to two orders of magnitude decrease in α2σ. This trend continues with x > 0.19 due to W precipitation. These findings indicate that dilute W additions below its solubility limit in CrN are important for realizing a high thermoelectric power factor in CrWxNz films. 

Co/biphenyldithiol (BPDT)/Co nanolayer sandwiches are synthesized by metal sputter deposition and molecular sublimation. These results indicate molecular-nanolayer-induced effects on the morphology and chemistry, of interest for hybrid nanolaminates. 

Introducing molecular nanolayers (MNLs) is attractive for enhancing the stability of, and inducing unusual properties at, inorganic thin film interfaces. Although organic molecules anchored to inorganic surfaces have been studied extensively, property enhancement mechanisms underpinned by molecular assemblies at inorganic thin film interfaces are yet to be revealed and understood. Here, ab initio molecular dynamics simulations of tensile strain of Au/MNL/Au thin film nanosandwich models provide insights into molecularly induced strain hardening and toughening. Au/MNL/Au nanosandwiches support up to ≈30% higher stresses and exhibit up to ≈140% higher toughness than pure Au slab models. Both hardening and toughening are governed by molecular length and terminal chemistry in the MNL. Strong Au/MNL interface bonding and greater molecular length promote defect creation in Au, which results in strain hardening. Accommodation of increasing post-hardening strains in the MNL mitigates the stress increase in the Au slabs, delays interface fracture, and contributes to toughening. Remarkably, toughening correlates with equilibrium interface strain, which could be used as a proxy for efficiently identifying promising inorganic/MNL combinations that provide toughening. Our findings are important for the discovery and design of inorganic–organic interfaces, nanomaterials, and composites. 

Intercalated layered materials offer distinctive properties and serve as precursors for important two-dimensional (2D) materials. However, intercalation of non–van der Waals structures, which can expand the family of 2D materials, is difficult. We report a structural editing protocol for layered carbides (MAX phases) and their 2D derivatives (MXenes). Gap-opening and species-intercalating stages were respectively mediated by chemical scissors and intercalants, which created a large family of MAX phases with unconventional elements and structures, as well as MXenes with versatile terminals. The removal of terminals in MXenes with metal scissors and then the stitching of 2D carbide nanosheets with atom intercalation leads to the reconstruction of MAX phases and a family of metal-intercalated 2D carbides, both of which may drive advances in fields ranging from energy to printed electronics. 

Advances in interface science over the last 20 years have demonstrated the use of molecular nanolayers (MNLs) at inorganic interfaces to access emergent phenomena and enhance a variety of interfacial properties. Here, we capture important aspects of how a MNL can induce multifold enhancements and tune multiple interfacial properties, including chemical stability, fracture energy, thermal and electrical transport, and electronic structure. Key challenges that need to be addressed for the maturation of this emerging field are described and discussed. MNL-induced interfacial engineering has opened up attractive opportunities for designing organic–inorganic hybrid nanomaterials with high interface fractions, where properties are determined predominantly by MNL-induced interfacial effects for applications. 

Controlling nanoporosity to favorably alter multiple properties in layered crystalline inorganic thin films is a challenge. Here, we demonstrate that the thermoelectric and mechanical properties of Ca 3 Co 4 O 9 films can be engineered through nanoporosity control by annealing multiple Ca(OH) 2 /Co 3 O 4 reactant bilayers with characteristic bilayer thicknesses (b t ). Our results show that doubling b t , e.g. , from 12 to 26 nm, more than triples the average pore size from ∼120 nm to ∼400 nm and increases the pore fraction from 3% to 17.1%. The higher porosity film exhibits not only a 50% higher electrical conductivity of σ ∼ 90 S cm −1 and a high Seebeck coefficient of α ∼ 135 μV K −1 , but also a thermal conductivity as low as κ ∼ 0.87 W m −1 K −1 . The nanoporous Ca 3 Co 4 O 9 films exhibit greater mechanical compliance and resilience to bending than the bulk. These results indicate that annealing reactant multilayers with controlled thicknesses is an attractive way to engineer nanoporosity and realize mechanically flexible oxide-based thermoelectric materials.