Data-Driven Discovery of Intrinsic Direct-Gap 2D Materials as Potential Photocatalysts for Efficient Water Splitting

Intrinsic direct-gap two-dimensional (2D) materials hold great promise as photocatalysts, advancing the application of photocatalytic water splitting for hydrogen production. However, the time- and resource-efficient exploration and identification of such 2D materials from a vast compositional and structural chemical space present significant challenges within the realm of materials science research. To this end, we perform a data-driven study to find 2D materials with intrinsic direct-gap and desirable photocatalytic properties for overall water splitting. By implementing a three-staged large-scale screening, which incorporates machine-learned data from the V2DB, high-throughput density functional theory (DFT), and hybrid-DFT calculations, we identify 16 direct-gap 2D materials as promising photocatalysts. Subsequently, we conduct a comprehensive assessment of materials properties that are related to the solar water splitting performance, which include electronic and optical properties, solar-to-hydrogen conversion efficiencies, and carrier mobilities. Therefore, this study not only presents 16 2D photocatalysts but also introduces a rigorous data-driven approach for the future discovery of functional 2D materials from currently unexplored chemical spaces

Anomalous Dependence of the Reactivity on the Presence of Steps: Dissociation of D₂ on Cu(211)

Stepped metal surfaces are usually assumed to exhibit an increased catalytic activity for bond cleavage of small molecules over their flat single-crystal counterparts. We present experimental and theoretical data on the dissociative adsorption of molecular hydrogen on copper that contradicts this notion. We observe hydrogen molecules to be more reactive on the flat Cu(111) than on the stepped Cu(211) surface. We suggest that this exceptional behavior is due to a geometric effect, that is, that bond cleavage on the flat surface does not occur preferentially over a top site

High Electrical Conductivity in Ni₃(2,3,6,7,10,11-hexaiminotriphenylene)₂, a Semiconducting Metal–Organic Graphene Analogue

Reaction of 2,3,6,7,10,11-hexa­amino­tri­phenyl­ene with Ni²⁺ in aqueous NH₃ solution under aerobic conditions produces Ni₃­(HITP)₂ (HITP = 2,3,6,7,10,11-hexa­imino­tri­phenyl­ene), a new two-dimensional metal–organic framework (MOF). The new material can be isolated as a highly conductive black powder or dark blue-violet films. Two-probe and van der Pauw electrical measurements reveal bulk (pellet) and surface (film) conductivity values of 2 and 40 S·cm^–1, respectively, both records for MOFs and among the best for any coordination polymer

High Electrical Conductivity in Ni₃(2,3,6,7,10,11-hexaiminotriphenylene)₂, a Semiconducting Metal–Organic Graphene Analogue

Reaction of 2,3,6,7,10,11-hexa­amino­tri­phenyl­ene with Ni²⁺ in aqueous NH₃ solution under aerobic conditions produces Ni₃­(HITP)₂ (HITP = 2,3,6,7,10,11-hexa­imino­tri­phenyl­ene), a new two-dimensional metal–organic framework (MOF). The new material can be isolated as a highly conductive black powder or dark blue-violet films. Two-probe and van der Pauw electrical measurements reveal bulk (pellet) and surface (film) conductivity values of 2 and 40 S·cm^–1, respectively, both records for MOFs and among the best for any coordination polymer

Layer-by-Layer Assembled Films of Perylene Diimide- and Squaraine-Containing Metal–Organic Framework-like Materials: Solar Energy Capture and Directional Energy Transfer

We demonstrate that thin films of metal–organic framework (MOF)-like materials, containing two perylenediimides (<b>PDICl</b>_<b>4</b>, <b>PDIOPh</b>_<b>2</b>) and a squaraine dye (<b>S1</b>), can be fabricated by layer-by-layer assembly (LbL). Interestingly, these LbL films absorb across the visible light region (400–750 nm) and facilitate directional energy transfer. Due to the high spectral overlap and oriented transition dipole moments of the donor (<b>PDICl</b>_<b>4</b> and <b>PDIOPh</b>_<b>2</b>) and acceptor (<b>S1</b>) components, directional long-range energy transfer from the bluest to reddest absorber was successfully demonstrated in the multicomponent MOF-like films. These findings have significant implications for the development of solar energy conversion devices based on MOFs