Jian Yang

Precisely constructing transition metal (TM) active sites in two-dimensional materials can enhance water splitting, whereas the role of geometric factors such as interfacial curvature remains poorly understood. Nanotubes (NTs) provide a well-defined curved architecture that can modulate electron interactions and reactivity. Here, we rationally design a series of TM@g-C6N6 NTs and use first-principles calculations assisted by machine learning to elucidate how dimensional reduction and curvature govern water-splitting activity. We find that reduced curvature radius systematically promotes water splitting. Notably, the Ir/Rh-decorated g-C6N6 NTs show remarkable electrocatalytic performance with calculated overpotentials of 0.05 eV for the hydrogen evolution reaction and 0.20 eV for the oxygen evolution reaction. Curvature-induced confinement drives reconstruction and reoccupation of the d-orbital states near the Fermi level upon transitioning from a flat plane to a tubular geometry. More importantly, for different reaction intermediates, we identify a curvature-dependent inversion of the dominant adsorption orbital transition from the dz2 to the dx2–y2, which directly correlates with enhanced catalytic activity. Our results establish interfacial curvature as a key manipulator for tuning electronic structure and water-splitting reactivity in TM@g-C6N6 NT single-atom catalysts and provide a new perspective on modulating electronic and catalytic properties in TM@g-C6N6 NT-like structures.

Transition metal dichalcogenide (TMD) lateral heterostructures provide unique platforms to study nanoscale physics, but progress is limited by the difficulty of producing high‐quality interfaces, which require atomic‐precision growth rather than simple stacking. We report a controllable two‐step chemical vapor deposition (CVD) process for directed epitaxy growth of MoS ₂ /WS ₂ monolayer lateral heterostructures. Atom‐resolution scanning tunneling microscopy measurements demonstrate an atomically sharp, defect‐free MoS ₂ /WS ₂ interface formed along the sulfur zigzag edge of MoS ₂ , indicating an atomic‐substitution‐nucleation growth mechanism. Domain sizes of both MoS ₂ and WS ₂ can be precisely tuned from several to hundreds of micrometers. The zig‐zag interface creates an intermediate energy level at the junction, prolonging photogenerated carrier recombination lifetimes, in agreement with theoretical band‐structure calculations. This work establishes a scalable synthesis route to high‐quality TMDs lateral heterostructures with an atomic‐scale shape interface and tunable domain sizes, accelerating the applications in electronic and optoelectronic devices.

Precisely constructing transition metal (TM) active sites in two-dimensional materials can enhance water-splitting, whereas the role of geometric factors such as interfacial curvature remain poorly understood. Nanotube (NT) provides a well-defined curved architecture that can modulate electron interactions and reactivity. Here, we rationally design a series of TM@g-C6N6 NTs and use first-principles calculations assisted by machine learning to elucidate how dimensional reduction and curvature govern water-splitting activity. We find that reduced curvature radius systematically promotes water splitting. Notably, the Ir- and Rh-decorated g-C6N6 NTs show remarkable electrocatalytic performance with calculated overpotentials of 0.05 eV for the hydrogen evolution reaction and 0.20 eV for the oxygen evolution reaction. Curvature-induced confinement drives reconstruction and reoccupation of the d-orbitals states near the Fermi level upon transitioning from a flat plane to a tubular geometry. More importantly, for different reaction intermediates, we identify a curvature-dependent inversion of the dominant adsorption orbital transition from the dz2 to the dx2-y2 , which directly correlates with enhanced catalytic activity. Our results establish interfacial curvature as a key manipulator for tuning electronic structure and water-splitting reactivity in TM@g-C6N6 NT single-atom catalysts and provide a new perspective on modulating electronic and catalytic properties in TM@g-C6N6 NT-like structures.

Transition metal selenides have attracted much attention in the field of energy storage materials due to their high theoretical capacity and suitable working potential. However, they still suffer from slow reaction kinetics and poor stability during cycling. The construction of heterostructures is an effective strategy to improve the electrochemical performance of materials, which can improve the diffusion kinetics of ions and enhance the conductivity and structural stability of electrodes. In this paper, an in situ self-assembly strategy is proposed to encapsulate VO(acac)₂ in a customized cavity of ZIF-8 to achieve uniform dispersion of vanadium species and then to obtain ZnSe/VSe₂@NC heterostructured materials with abundant heterointerface. Based on the experimental characterization combined with density-functional theory calculations, a strong built-in electric field is induced at the interface due to the large energy band structure difference between VSe₂ and ZnSe, which promotes charge-electron transfer and achieves fast electrochemical kinetics and satisfactory reversible capacity. As an anode material for sodium-ion batteries (SIBs), ZnSe/VSe₂@NC exhibits excellent multiplicity performance (254.46 mA h g^-1 at 10 A g^-1) and long cycle stability (317.52 mA h g^-1 after 2000 cycles at 5 A g^-1). This study provides an effective strategy for the rational design of anode materials for high-performance SIBs.

The rational design of heterojunctions by coupling two or more two-dimensional (2D) materials is regarded as a feasible strategy to efficiently enhance photocatalytic-hydrogen performance by capturing solar energy to address the increasing global energy crisis. In this work, a functional MoS₂/ZnO heterojunction is proposed based on first-principles simulation. Our results reveal that the photogenerated electrons and holes in the MoS₂/ZnO heterojunction follow a specific Z-scheme pathway, highly facilitating redox reactions and optimizing optical properties in the visible-light region. Under external strain, the MoS₂/ZnO heterojunction demonstrates improved HER performance and remarkable optical-harvesting capabilities. Interestingly, the HER free energy for the heterojunction is only -0.04 eV under -5% compressive strain, highlighting its promising potential for photocatalytic hydrogen production. We observe that the absorption edge of the spectrum shifts gradually to the infrared region with increasing tensile biaxial strains, whereas compressive biaxial strains result in a blue-shift absorption spectrum. Additionally, all heterojunctions achieve excellent solar-to-hydrogen (STH) efficiencies exceeding 10%, demonstrating their capability to store sufficient solar energy. Our work offers a novel strategy for exploring highly efficient photocatalysts in the field of hydrogen energy with the ability to modulate their activity through external strain.

Strategically engineering heterojunctions through the integration of two or more monolayer materials presents a promising avenue for augmenting the efficiency of solar‐driven overall water splitting, which holds the potential for mitigating the escalating environmental challenges. Herein, based on first‐principles calculations, the functional type‐II g‐C ₆ N ₆ /As heterojunction is first constructed by g‐C ₆ N ₆ and As, then, systematically investigated its structural stability, optoelectronic properties and photocatalytic mechanism and potential for catalyzing water splitting, respectively. Owing to the band‐bending effect and the built‐in electric field induced across the heterojunction interface, the photogenerated electrons and holes on the surface could effectively separate and extend their carrier lifetimes. The heterojunction as a type‐II system photocatalyst with the hydrogen and oxygen evolution reactions occurring, respectively, happen at g‐C ₆ N ₆ and As surfaces. The heterojunction requires only an additional voltage of 0.29 V to ensure the photoinduced holes provide sufficient energy to drive the OER process. The introduction of single‐layer As could effectively adjust the reaction energy barrier of the HER activity for single‐layer g‐C ₆ N ₆ , thus ultimately significantly enhancing HER performance of heterojunction. More significantly, the heterojunction breaks the optical‐capturing obstacle of the g‐C ₆ N ₆ and exhibits strong optical capture capability in the regions from the infrared to visible light. Meanwhile, the value of the STH efficiency for heterojunction is up to 28.18%, which exceeds the value of the economically feasible requirement (10%). The above results are beneficial for the quantified design and application of photocatalytic heterojunction for overall water splitting and offer valuable insights for potential commercial implementations.