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The weaker van der Waals force between layers inhibits the interlayer electron migration, which greatly limiting the enhancement of the photocatalytic activity over graphitic carbon nitride (g-C 3 N 4). Herein, the metal-free sulfur-doped 2D/3D van der Waals (vdW) homojunction (2D/3D CNSCN) that containing 2D sulfur-doped g-C 3 N 4 nanosheets (CNS) and 3D g-C 3 N 4 flower-like hierarchical structure (CN) was fabricated. Thanks to the cooperative effect of 2D-3D structural and good compatibility between CNS and CN, an in situ formed 2D/3D vdW homojunction served as the driving force for promoting charge carrier separation and transfer. The optimal photocatalytic H 2 evolution of 2D/3D CNSCN reached up to 2196 μmol h−1g−1, which was 4.1 and 3.2 times higher than that of CN and CNS, respectively. 10 mg of the 2D/3D CNSCN photocatalyst was able to totally remove of rhodamine B (RhB) solution in less than 80 min under the visible light. This study provides new opportunities to construct novel 2D/3D mixed-dimensional vdW homojunction, and broad interest in vdW homojunction research for the applications in energy conversion and environmental protection field. [Display omitted] • 2D/3D mixed-dimensional vdW homojunction of CN is prepared for the first time. • CNSCN has high activity and stability in photocatalytic H 2 evolution and removing RhB. • The optimal photocatalytic H 2 evolution of 2D/3D CNSCN reaches up to 2196 μmol h−1g−1. • CNSCN exhibits ultrahigh charge-carrier separation and transfer efficiency. • A possible photocatalytic mechanism is proposed. [ABSTRACT FROM AUTHOR]

The substitutions of Ni and Ti/Ni by 5 at% Pd in Nb 51 W 5 Ti 23 Ni 21 alloy were performed and the alloying effects of Pd on microstructures and hydrogen transport properties were investigated. The description of hydrogen permeation flux based on hydrogen chemical potentials was applied to depict the dependence of hydrogen permeation flux on hydrogen solubility. Substituting Ni and Ti/Ni by Pd cause the reduced hydrogen solubility, leading to the enhanced resistance to hydrogen embrittlement. The Pd substituting Ni and Ti/Ni induce the decreased hydrogen permeation flux, which can be attributed to the decreased hydrogen solubility and the slightly decreased intrinsic hydrogen diffusion coefficient. The Nb 51 W 5 Ti 23 Ni 16 Pd 5 alloy membranes exhibits strong resistance to hydrogen embrittlement which shows no failure when cooled down to room temperature under hydrogen atmosphere. [Display omitted] • 5 at.% Pd substituting Ni and Ni/Ti were performed on Nb 51 W 5 Ti 23 Ni 21 alloy. • The hydrogen solubility decreased by 7.3% after 5 at.% Pd substituting Ni. • Nb 51 W 5 Ti 23 Ni 16 Pd 5 shows no hydrogen embrittlement failure when cooled down to room temperature. [ABSTRACT FROM AUTHOR]

Although graphitic carbon nitride is a promising photocatalyst in the field of energy conversion and environmental purification, the intrinsic properties like excitonic effects and sluggish charge transfer restrict further photocatalytic applications. To circumvent these limitations, the novel all-organic heterojunction photocatalysts were constructed by anchoring organic carbon dots (O-dots) on porous graphitic carbon nitride nanosheets (O-dots/CNS). Results demonstrated that excitons can be effectively dissociated into electrons and holes at the interface of O-dots/CNS heterojunction, followed by holes injected to O-dots and electrons accumulated in CNS to realize efficient charge separation. Consequently, the O-dots/CNS with the optimized hydrogen (H 2) evolution performance could be reached 1564.5 μmol h−1g−1 under the visible light irradiation. This work not only presents new ideas for rational design photocatalytic reaction system from exciton and charge carrier, but also broaden the applications of this new kind of organic dots in the field of energy conversion. [Display omitted] • An all-organic heterojunction is constructed by carbon nitride and organic dots. • The exciton can be dissociated at the interface of all-organic heterojunction. • The heterojunction catalyst remarkably enhances photocatalytic H 2 evolution. • A possible photocatalytic mechanism is proposed. [ABSTRACT FROM AUTHOR]

Here, a dual regulation strategy to construct nitrogen vacancies-modified and metal-free group-intercalated g-C 3 N 4 (NP–CN) photocatalyst is proposed. The nitrogen vacancies in the planes of NP-CN could adjust the band-gap of CN, while the metal-free group intercalated between layers act as electron transport channels for fast charge carrier separation. The nitrogen vacancies as well as metal-free group intercalate significantly increase the photocatalytic performance in H 2 evolution and dye degradation. The photocatalytic H 2 evolution rate and apparent first-order rate constant for RhB removal of NP-CN24 is 22 and 7.3 times higher than that CN, respectively. This work provides a facile approach to design and synthesize new modification of CN photocatalyst via nitrogen vacancies and metal-free group intercalation to simultaneously improve the activity in the photocatalytic application field. • Nitrogen vacancies-modified and metal-free group-intercalated g-C 3 N 4 (NP–CN) is prepared. • NP-CN shows high activity and stability in photocatalytic H 2 evolution and dye degradation. • The photocatalytic H 2 evolution activity of NP-CN is 22 time that of the pristine g-C 3 N 4. [ABSTRACT FROM AUTHOR]