Marie-Christine Record

Chalcogenides challenge materials artificial intelligence (AI) because their properties depend on defects, disorder, metastability, interfaces, processing history, and operating conditions, as well as composition and structure. This review examines AI applications across transition-metal dichalcogenides, photovoltaic materials, thermoelectrics, phase-change materials, chalcogenide perovskites, and glasses. It combines structured bibliographic analysis with critical assessment of representative studies rather than exhaustive evaluation of all retrieved publications. Its central contribution is a claim-specific, five-level evidence framework: Level 0, method transfer or proposal; Level 1, internal retrospective validation; Level 2, domain-aware or external validation; Level 3, prospective computational or experimental validation; and Level 4, closed-loop operation in which new results guide subsequent decisions. Evidence levels characterize individual claims, not entire papers. Descriptor-based models, graph neural networks, and machine-learned interatomic potentials offer complementary capabilities, but predictive accuracy alone does not establish transferability or practical reliability. Prospective validation is documented in selected prediction, synthesis, and processing applications. Among the chalcogenide-specific studies examined, however, no workflow met the Level 4 criteria for repeated model-updated closed-loop operation. Progress requires traceable datasets, leakage-resistant evaluation, uncertainty assessment under relevant distribution shifts, physically meaningful validation, and stronger connections between modelling, synthesis, processing, and characterization. The framework clarifies existing evidence and priorities for future validation.

Addressing global energy and environmental issues calls for the development of effective photocatalysts capable of enabling solar-driven water splitting, a key route toward sustainable hydrogen generation. In this work, we conducted a detailed density functional theory (DFT) study on three bilayer van der Waals (vdW) heterojunctions, Ga₂SSe/GaP, Ga₂SSe/PtSSe, and Ga₂SSe/SnSSe, each explored in four distinct stacking configurations, with Ga₂SSe serving as the base monolayer. We assessed their structural stability, electronic properties, and optical responses to determine their suitability for photocatalytic water splitting. The analysis showed that Ga₂SSe/GaP and Ga₂SSe/SnSSe exhibit type-II band alignment, while Ga₂SSe/PtSSe displays a type-I alignment. Electrostatic potential profiles and Bader charge calculations identified SeGa₂S/SSnSe and SeGa₂S/SeSnS as direct Z-scheme systems, offering efficient charge carrier separation and robust redox potential. For effective water splitting, the band edges must straddle the water redox potentials. Our results indicate that configurations A and B in Ga₂SSe/GaP, along with C and D in Ga₂SSe/SnSSe, fulfill this requirement. These four configurations also exhibit strong absorption in both the visible and ultraviolet spectral ranges. Notably, configurations C and D of Ga₂SSe/SnSSe achieve high solar-to-hydrogen (STH) efficiencies, reaching 38.44% and 21.75%, respectively. Overall, our findings suggest that these direct Z-scheme heterostructures are promising candidates for water splitting photocatalysis.

Cycling-induced evolution of the Co₃O₄ shell into dispersed Co/CoO nanoparticles ensures long-term stability. Meanwhile, interfacial charge redistribution elevates the oxidation states of Ti and Co and lowers the ion migration barrier.

Harnessing solar energy for photocatalytic water splitting and hydrogen fuel production necessitates the development of advanced photocatalysts with broad solar spectrum absorption and efficient electron-hole separation. In this study, we systematically explore the potential of the SGa₂Se/TeMoS heterojunction as a water-splitting photocatalyst using first-principles calculations. Our results indicate that while the heterojunction exhibits type-II band alignment, its band edge positions are inadequate for initiating water redox reactions. To overcome this limitation, we successfully engineered a Z-scheme SGa₂Se/Zr/TeMoS heterojunction by incorporating a Zr layer to modulate the charge transfer mechanism between the SGa₂Se and TeMoS layers. The potential positions of the HER and OER in this Z-scheme heterojunction overcome the limitation of the bandgap on water decomposition, allowing the optimized heterojunction to exhibit suitable band edge positions for water splitting across a wide pH range (0 ≤ pH ≤ 11.3), from acidic to weakly basic conditions. Additionally, the heterojunction exhibits exceptional light absorption capabilities across the entire spectrum, particularly in the infrared and visible regions, which greatly enhances the utilization of solar energy and highlights its potential as an efficient broad-spectrum photocatalyst for water splitting.

Constructing van der Waals heterojunctions with excellent properties has attracted considerable attention in the field of photocatalytic water splitting. In this study, four patterns, coined A, B, C, and D of Janus Ga₂SSe/Bi₂O₃ van der Waals (vdW) heterojunctions with different stacking modes, were investigated using first-principles calculations. Their stability, electronic structure, and optical properties were analyzed in detail. Among these, patterns A and C heterojunctions demonstrate stable behavior and operate as direct Z-scheme photocatalysts, exhibiting band gaps of 1.83 eV and 1.62 eV. In addition, the suitable band edge positions make them effective for photocatalytic water decomposition. The built-in electric field across the heterojunction interface effectively inhibits electron-hole recombination, thereby improving the photocatalytic efficiency. The optical absorption coefficients show that patterns A and C heterojunctions exhibit higher light absorption intensity than Ga₂SSe and Bi₂O₃ monolayers, spanning from the ultraviolet to visible range. Their corrected solar-to-hydrogen (STH) efficiencies are 13.60% and 12.08%, respectively. The application of hydrostatic pressure and biaxial tensile strain demonstrate distinct effects on photocatalytic performance: hydrostatic pressure preferentially enhances the hydrogen evolution reaction (HER), while biaxial tensile strain primarily improves the oxygen evolution reaction (OER). Furthermore, the heterojunctions exhibited enhanced optical absorption across the UV-visible spectrum with increasing hydrostatic pressure. Notably, a 1% tensile strain results in an improvement in visible light absorption efficiency. These results demonstrate that Ga₂SSe/Bi₂O₃ heterojunctions hold great promise as direct Z-scheme photocatalysts for overall water splitting.