Ningxia University

Partial denitrification coupled with anammox (PD/A) is a promising energy-efficient alternative for mainstream nitrogen removal, yet its stability under different reactor modes remains unclear. This study systematically compared sequencing batch (R_S) and continuous-flow (R_C) PD/A systems using performance monitoring, activity assays, and metagenomic analyses. R_C maintained superior long-term stability, achieving >80% nitrogen removal with anammox contributing above 90%, whereas R_S remained less stable (∼65% NRE, ∼75% anammox contribution) and relied more on complete denitrification. Activity assays revealed that PD activity in R_S was 5.03 times that of anammox, favoring complete denitrification. In contrast, R_C maintained balanced activities, with PD activity being 0.89 times that of anammox, supporting cooperative PD/A interactions. Metagenomic analysis further revealed that Thauera-associated Nir/Nor/Nos genes were markedly enriched in R_S, indicating a stronger potential for complete denitrification. These findings demonstrate that reactor mode regulates PD/A interactions through distinct stabilization mechanisms, with continuous-flow operation enhancing microbial cooperation and system resilience. This study provides mechanistic insights and practical guidance for the stable implementation of mainstream PD/A processes.

The efficient removal of pollutants and solar-driven hydrogen production are crucial for advancing a green economy, yet their practical implementation remains challenging. In this study, we shortened the transport path of photogenerated charge carriers and increased the interfacial contact area by exfoliating 3D nickel metal-organic frameworks (Ni-MOFs) into 2D nickel metal-organic layers (Ni-MOLs). A 3D/2D CdIn₂S₄/Ni-MOLs (CIS/NM) type-II heterojunction was successfully constructed via a one-pot solvothermal method, in which 3D CdIn₂S₄ was grown in situ on 2D Ni-MOLs. This heterojunction demonstrated synergistic and efficient adsorption-photocatalytic degradation of methylene blue (MB) and photocatalytic hydrogen production. Adsorption tests revealed that 1.5 CIS/NM achieved a capacity of 38.2 mg g^-1 for MB (30 mg L^-1) within 240 min, following the Langmuir isotherm model and pseudo-second-order kinetics. Under optimized initial MB concentration and pH conditions (C₀ = 10 mg L^-1, pH = 11), the synergistic removal efficiency of 1.5 CIS/NM reached 99.9 %. Density functional theory (DFT) calculations and mechanistic studies confirmed the formation of a type-II heterojunction between CdIn₂S₄ and Ni-MOLs, with •OH and •O₂^- identified as the dominant reactive radicals. Furthermore, 1.5 CIS/NM exhibited excellent photocatalytic hydrogen evolution performance, with a rate of 1247 μmol g^-1 h^-1 and an apparent quantum efficiency of 8.1 % at 400 nm. This study offers a straightforward synthesis strategy for achieving adsorption-degradation of pollutants and solar hydrogen production, providing new insights for the design of bifunctional photocatalysts.

Li-rich layered oxides are promising high-energy-density cathodes for next-generation Li-ion batteries, yet their practical application is hindered by structural instability arising from oxygen redox activity, which typically results in a trade-off between achieving a high discharge specific capacity and maintaining a high Coulombic efficiency. Herein, we employ machine learning to identify key synthesis factors governing the initial Coulombic efficiency in Li_1.2Ni_0.13Co_0.13Mn_0.54O₂. Four machine learning models were trained with a data set of 203 samples. Among them, the gradient boosting decision tree exhibited superior predictive accuracy (R² = 0.802 on the test set) and identified the lithium-to-transition metal ratio and presintering atmosphere as critical parameters. Machine learning-guided synthesis reveals that presintering in air at low temperatures reduces the Li₂MnO₃ phase proportion, promotes the exposure of the {010} planes favorable for Li⁺ transport, and mitigates the formation of surface rock-salt. This approach yielded a high discharge capacity of 301.02 mAh g^-1 and an initial Coulombic efficiency of 81.05%, highlighting the effective integration of data-driven design with experimental synthesis for advanced Li-rich layered oxide optimization.