Qimin Yan

Elastic properties of chemical-vapor-deposited monolayer MoS2, WS2, and their bilayer heterostructures.

Elastic properties of materials are an important factor in their integration in applications. Chemical vapor deposited (CVD) monolayer semiconductors are proposed as key components in industrial-scale flexible devices and building blocks of two-dimensional (2D) van der Waals heterostructures. However, their mechanical and elastic properties have not been fully characterized. Here we report high 2D elastic moduli of CVD monolayer MoS2 and WS2 (∼170 N/m), which is very close to the value of exfoliated MoS2 monolayers and almost half the value of the strongest material, graphene. The 2D moduli of their bilayer heterostructures are lower than the sum of 2D modulus of each layer but comparable to the corresponding bilayer homostructure, implying similar interactions between the hetero monolayers as between homo monolayers. These results not only provide deep insight into understanding interlayer interactions in 2D van der Waals structures but also potentially allow engineering of their elastic properties as desired.

Solar fuels photoanode materials discovery by integrating high-throughput theory and experiment

Significance Combining high-throughput computation and experiment accelerates the discovery of photoelectrocatalysts for water oxidation and explains the origin of their functionality, establishing ternary metal vanadates as a prolific class of photoanode materials for generation of chemical fuels from sunlight. The limited number of known low-band-gap photoelectrocatalytic materials poses a significant challenge for the generation of chemical fuels from sunlight. Using high-throughput ab initio theory with experiments in an integrated workflow, we find eight ternary vanadate oxide photoanodes in the target band-gap range (1.2–2.8 eV). Detailed analysis of these vanadate compounds reveals the key role of VO4 structural motifs and electronic band-edge character in efficient photoanodes, initiating a genome for such materials and paving the way for a broadly applicable high-throughput-discovery and materials-by-design feedback loop. Considerably expanding the number of known photoelectrocatalysts for water oxidation, our study establishes ternary metal vanadates as a prolific class of photoanode materials for generation of chemical fuels from sunlight and demonstrates our high-throughput theory–experiment pipeline as a prolific approach to materials discovery.

The role of the CeO2/BiVO4 interface in optimized Fe–Ce oxide coatings for solar fuels photoanodes

Solar fuel generators entail a high degree of materials integration, and efficient photoelectrocatalysis of the constituent reactions hinges upon the establishment of highly functional interfaces. The recent application of high throughput experimentation to interface discovery for solar fuels photoanodes has revealed several surprising and promising mixed-metal oxide coatings for BiVO4. Using sputter deposition of composition and thickness gradients on a uniform BiVO4 film, we systematically explore photoanodic performance as a function of the composition and loading of Fe–Ce oxide coatings. This combinatorial materials integration study not only enhances the performance of this new class of materials but also identifies CeO2 as a critical ingredient that merits detailed study. A heteroepitaxial CeO2(001)/BiVO4(010) interface is identified in which Bi and V remain fully coordinated to O such that no surface states are formed. Ab initio calculations of the integrated materials and inspection of the electronic structure reveals mechanisms by which CeO2 facilitates charge transport while mitigating deleterious recombination. The results support the observations that addition of Ce to BiVO4 coatings greatly enhances photoelectrocatalytic activity, providing an important strategy for developing a scalable solar fuels technology.

Prediction of TiRhAs as a Dirac nodal line semimetal via first-principles calculations

Using first-principles calculations we predict that

Mn2V2O7: An Earth Abundant Light Absorber for Solar Water Splitting

mathrm{TiRhAs}

High Throughput Discovery of Solar Fuels Photoanodes in the CuO-V_2O_5 System

, a previously synthesized compound, is a Dirac nodal line (DNL) semimetal. The DNL in this compound is found to be protected both by the combination of inversion and time-reversal symmetry, and by a reflection symmetry, in the absence of spin-orbit coupling (SOC). Our calculations show that band velocities associated with the nodal line have a high degree of directional anisotropy, with in-plane velocities

Stability and self-passivation of copper vanadate photoanodes under chemical, electrochemical, and photoelectrochemical operation

v_perp

Discovery of Manganese-Based Solar Fuel Photoanodes via Integration of Electronic Structure Calculations, Pourbaix Stability Modeling, and High-Throughput Experiments

perpendicular to the nodal line between

First-principles study of electronic structure and photocatalytic properties of MnNiO3 as an alkaline oxygen-evolution photocatalyst

1.2-2.8times10^5

Data-driven discovery of new Dirac semimetal materials

m/s. The crossings along the DNL are further found to exhibit a prominent and position-dependent tilt along directions perpendicular to the nodal line. We calculate