SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4263-3
Monolayer black phosphorus (phosphorene) exhibits a direct bandgap and strong in-plane anisotropy, making it a promising candidate for near-infrared (NIR) optoelectronic devices. However, the precise modulation of its excitonic emission via anisotropic strain remains insufficiently understood, particularly regarding the contrasting strain responses of phosphorene versus transition metal dichalcogenides (TMDs). Here, we combine experimental characterization with tight-binding (TB) modeling to elucidate the strain-dependent bandgap evolution in phosphorene. Using a four-band TB model, we derive the bandgap at the Γ point as E_g^BP = 4t1 + 2t2 + 4t3 + 2t5, with hopping parameters t1 = -1.220 eV, t2 = 3.665 eV, t3 = -0.205 eV, t4 = -0.105 eV, and t5 = -0.055 eV. Under tensile strain along the zigzag (ZZ) direction, the interatomic distance associated with t1 increases, reducing the magnitude of |t1|. Since t1 is negative, the bandgap increases, contrary to the behavior of monolayer MoS2, where tensile strain decreases the bandgap due to positive hopping parameters t11, t22, and t12. This anisotropic strain response enables selective tuning of NIR exciton emission. Our findings provide a quantitative framework for strain engineering in phosphorene-based NIR devices, highlighting the critical role of hopping parameter signs in determining bandgap modulation.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202605013
The escalating eutrophication of aquatic systems has intensified algal blooms, leading to substantial release and accumulation of algal-derived dissolved organic matter (ADOM), which profoundly influences carbon cycling and pollutant transport. Iron minerals, particularly ferrihydrite, are recognized as critical mediators of DOM sequestration, yet the adsorption fractionation of ADOM under varying environmental conditions remains poorly understood. This study systematically investigated the effects of pH (2.0–10.0) and initial dissolved organic carbon (DOC) concentration (2–100 mg C/L) on the adsorption capacity and selectivity of ADOM onto ferrihydrite, employing UV-Vis spectroscopy and excitation-emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC). Results demonstrated that adsorption capacity increased with pH from 2.0 to 7.0, reaching a maximum of 21.59 mg C/g at pH 7.0, followed by a decline at pH > 7.0 due to enhanced electrostatic repulsion. Within the environmentally relevant pH range of 3.0–9.0, selective fractionation intensified with increasing pH, favoring highly aromatic, high-molecular-weight chromophoric DOM (CDOM) and protein-like/aromatic amino acid fluorescent DOM (FDOM) with high humification and autochthonous characteristics. With increasing initial DOC concentration, adsorption exhibited non-linear growth, with preferential uptake of low-aromaticity, high-molecular-weight CDOM and protein-like FDOM of lower humification and stronger autochthonous features. These findings elucidate that ferrihydrite can effectively sequester reactive ADOM components via pH- and concentration-dependent selective adsorption, potentially altering DOM composition and reactivity in eutrophic waters, thereby providing fundamental data for understanding iron mineral-mediated internal carbon sequestration.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3387-6
Defect engineering is pivotal in comprehending physical mechanisms that govern carrier transport and device performance. The defect evolution and carrier manipulation in Sn-doped Ga2O3 bulk crystals subjected to different thermal treatments were investigated, utilizing depth-profiled deep-level transient spectroscopy (DLTS) and frequency-dependent capacitance-voltage (C-V-f) techniques. In untreated Sn-doped Ga2O3 with an electron concentration of 6.37×10^17 cm^-3, two dominant electron traps, ET1 (EC−0.68 eV) and ET2 (EC−0.76 eV), were identified, corresponding to gallium vacancy (VGa) and the neutral complex of VGa-VO, respectively, and characterized as bulk traps. FeGa-related defects, ET3 (EC−0.84 eV), were concentrated near surface. Nitrogen annealing significantly reduced ET1, increased ET2 density from 6.13×10^15 to 1.1×10^16 cm^-3, and raised the interfacial state density (Dit) to 3.36×10^15 eV^-1 cm^-2, accompanied by an elevated electron concentration of 7.48×10^18 cm^-3. In contrast, air annealing enhanced ET1, with a density of 1.42×10^16 cm^-3, suppressed of ET2/ET3 traps, resulting in a lower Dit of 1.74×10^14 eV^-1 cm^-2, and a reduced electron concentration to 3.01×10^16 cm^-3. The findings reveal that a reducing environment induces VO formation and converts discrete VGa acceptors into neutral VGa-VO complexes, leading to downward surface band bending and electron accumulation. Conversely, VGa-VO complexes are dissociated into VGa acceptors in oxidizing conditions, leading to an upward surface band bending and electron compensation. This work underscores the carrier concentration manipulation by defect engineering in Ga2O3, offering insights essential for developing high-performance gallium oxide electronics.