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[Display omitted] • SubPc-3/Ag 3 PO 4 direct S -scheme supramolecular semiconductors were successfully fabricated. • Photocatalytic performance of SubPc-3/Ag 3 PO 4 for organic pollutants improved obviously. • Experimental and theoretical demonstrated the electron transfer mechanism between SubPc-3 and Ag 3 PO 4. • Photodegradation pathways were proposed based on DFT and experimental results. This study demonstrates the successful construction of a hybrid van der Waals heterostructure (vdWH) consisting of 3D supramolecular networks and 2D semiconductor Ag 3 PO 4 , using hydrogen-bonded 3D networks H 12 SubPcB-OPh 2 OH self-assembled onto Ag 3 PO 4. The resulting organic/inorganic vdWH exhibits significantly enhanced photocatalytic degradation efficiency for oxytetracycline (OTC) and tetracycline (TC) under visible light irradiation, with apparent rate constants 1.8 and 1.5 times higher than those of pristine Ag 3 PO 4 , respectively. Moreover, after five photocatalytic cycles, the photocatalytic activity of vdWH was still much higher than that of pristine Ag 3 PO 4. Molecular dynamics simulations indicate that the SubPc-3 supramolecular assembly is more prone to forming a 3D hydrogen bonding network rather than a 1D columnar stacking. In-situ irradiated X-ray photoelectron spectroscopy analyses and theoretical calculations confirm that the charge transfers between H 12 SubPcB-OPh 2 OH and Ag 3 PO 4 are consistent with the S-scheme mechanism. This work provides a promising strategy for designing and fabricating efficient and stable supramolecular self-assembled semiconductor-based photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen atoms adjacent to Mo in Bi 2 MoO 6 can be removed by UV treatment. • Neutron scattering was used to study the content and structure of defects in Bi 2 MoO 6. • Oxygen vacancies improve the optical properties of Bi 2 MoO 6 /MXene heterojunction. • Oxygen vacancies enhance the reactants adsorption and activation on Bi 2 MoO 6 surface. • Bi 2 MoO 6 /MXene with defects shows high NO removal efficiency under visible light. Defect engineering is an effective approach to improve the gas conversion properties of photocatalysts. However, revealing the defect microstructures and performance enhancing mechanism remain challenges. In this work, the precise content and atomic-level structure of oxygen vacancy in Bi 2 MoO 6 /MXene heterojunction photocatalyst was studied by neutron scattering. Pair distribution function analysis shows that the vacancy percentage of oxygen connected with Mo in Bi 2 MoO 6 is 16.6%, and the metal-O bond length decreases near the vacancy. The performance enhancement mechanism of oxygen vacancy in Bi 2 MoO 6 /MXene towards photocatalytic NO oxidation was investigated through experiments and density functional theory (DFT) calculations. The optical properties of the heterojunction photocatalyst can be significantly improved by the oxygen vacancies. The exposed Mo atoms at the vacancies greatly benefit the adsorption and activation of reactants, and also accelerate the generation of reactive oxygen species. The NO removal efficiency of the oxygen vacancy-containing Bi 2 MoO 6 /MXene heterojunction can reach up to 94.3% under visible light. This work provides a new approach for studying the microstructure and activity enhancement mechanism of oxygen vacancy in photocatalysts. [ABSTRACT FROM AUTHOR]

In the work, visible-light-driven ZnIn 2 S 4 /TiO 2-x nanotube arrays were fabricated by defect-induced bandgap engineering, leading to high visible light responsive, and combining ZnIn 2 S 4 cocatalyst to improve separation of photogenerated carriers, thus enhancing photocatalytic H 2 production. [Display omitted] • A visible-light-driven ZnIn 2 S 4 /TiO 2-x nanotube arrays for fabricating the highly efficient photocatalysts is proposed. • The in-plane oxygen vacancies induce the high visible light responsive of TiO 2-x. • ZnIn 2 S 4 /TiO 2-x nanotube arrays prompt synergistic regulations of both absorption and separation benefits. • ZnIn 2 S 4 /TiO 2-x nanotube arrays exhibit high and stable photocatalytic hydrogen evolution. Photocatalytic H 2 evolution provides an upcoming route for the production of clean fuel via the conversion of solar energy. TiO 2 , as a potential semiconductor material, is restricted by its faint absorption of visible light, thus limiting its application in water splitting. Herein, high visible light responsive ZnIn 2 S 4 /TiO 2-x nanotube arrays for photocatalytic hydrogen evolution were fabricated by two-step reaction. ZnIn 2 S 4 /TiO 2-x nanotube arrays exhibited the photo response from UV to visible-light region due to the introduction of oxygen vacancies and visible-light driven ZnIn 2 S 4. Moreover, the heterojunction improved the separation of photogenerated carriers and boosted the electron transfer from ZnIn 2 S 4 to TiO 2-x , thereby increasing the longevity of active electrons, which enhanced the photocatalytic activity for hydrogen evolution. An outstanding H 2 production rate of 581.1 μmol h−1 g−1 was obtained and an apparent quantum yield (AQY) up to ∼ 1.42% was achieved. This work demonstrates that the defect-induced bandgap engineering of semiconductor photocatalysts is a potential way to extend the optical absorption property of TiO 2 to visible light even or NIR and enhance the photocatalytic activity. [ABSTRACT FROM AUTHOR]

Ternary heterojunction CN/TiO 2 -Ti 3 C 2 constructed by CN and partially oxidized Ti 3 C 2 MXene exhibits excellent performance for visible-light photocatalystic NOx removal. [Display omitted] • Ti 3 C 2 MXene can be turned to TiO 2 -Ti 3 C 2 nanosheet by partially oxidation. • Ternary heterojunction catalyst was formed by g-C 3 N 4 and partially oxidized Ti 3 C 2. • NO conversion on the catalyst is inferred to S-scheme heterojunction mechanism. • NO removal efficiency of the photocatalyst reaches up to 66.3% under visible light. Highly efficient composite photocatalysts were prepared through annealing partially oxidized Ti 3 C 2 MXene with melamine under N 2 flow. The two-dimensional Ti 3 C 2 MXene was aforehand partially oxidized to form TiO 2 -Ti 3 C 2 nanosheet by precisely controlling the oxidation conditions. Ternary g-C 3 N 4 /TiO 2 /Ti 3 C 2 MXene photocatalyst was constructed by coating melamine derived g-C 3 N 4 on TiO 2 -Ti 3 C 2 nanosheet. The photogenerated electron-hole separation was significantly enhanced by the S-scheme heterojunction. Ti 3 C 2 tightly bonded with TiO 2 benefits transfer and aggregation of photo-induced holes. The composite material has an interconnected nanosheet structure, which increases the absorption of light and the reaction interface between gaseous reactant and photocatalysts. When evaluated as NOx purification photocatalysts, the fabricated composites get the high NO removal efficiency and low NO 2 generation. Under visible light, NO removal efficiency of the composite photocatalyst can reach up to 66.3%, which is significantly better than the g-C 3 N 4 or TiO 2 -Ti 3 C 2. This work demonstrates that moderately oxidized Ti 3 C 2 MXene is a good candidate for the construction of high-performance air purification photocatalysts. [ABSTRACT FROM AUTHOR]