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A stable heterometallic (Co, Ni)-MOF array with a 3D hierarchical flower-like morphology was coated onto the coral-like WO 3 /W thin film. The optimal (Co, Ni)-MOF/WO 3 /W photoanode exhibits a high photocurrent density of 2.96 mA cm−2 at 1.23 V in the 0.5 M Na 2 SO 4 solution and the photoelectrochemical (PEC) cell displays an excellent solar-to-hydrogen (STH) efficiency (2.17 %) under AM 1.5 G solar light. Moreover, the separation behavior and spatial distribution of photogenerated charges have been demonstrated by photo-assisted Kelvin probe force microscopy (KPFM). Furthermore, the shift of the d -band center and the change of Gibbs free energy for oxygen evolution reaction (OER) are realized by density functional theory (DFT) calculations. Overall, the coupling effect of these ions of Co2+, O2−, Ni2+, and W6+ could result in an electron delocalization in the (Co, Ni)-MOF/WO 3 /W photoanode, boosting the OER activity and finally improving the PEC water splitting performance. [Display omitted] • A flower-like (Co, Ni)-MOF array was deposited onto the WO 3 /W thin film. • The electron delocalization among the Co2+, Ni2+, W6+, and O2− ions was investigated. • The (Co, Ni)-MOF/WO 3 /W photoanode exhibits a photocurrent density of 2.96 mA cm−2. • The optimal (Co, Ni)-MOF/WO 3 /W shows the highest STH efficiency (2.17 %). • The electron transport was regulated by varying degrees of e g orbitals filling eventually. [ABSTRACT FROM AUTHOR]

It remains challenging for the fabrication of metal-organic framework (MOF)/semiconductor heterojunction photocatalysts with close contact interfaces. In this work, a novel MOF/semiconductor heterojunction photocatalyst consisting of H 2 O 2 -modified TiO 2 nanotubes (H 2 O 2 -TNTs) and MIL-88B(Fe)-NH 2 (labeled as H-T/M) was firstly constructed based on the hydrogen-bonded combination between the O atoms from –OOH groups resulting from H 2 O 2 absorbed on the surface of TiO 2 nanotubes and the H atoms of the –NH 2 group in MOF. The significantly enhanced photocatalytic property of the H-T/M heterojunction for reducing Cr(VI) could be ascribed to the accelerated interfacial electron transfer dynamics by a channel of hydrogen bonds (N···H–O–O–Ti), which could be extracted from the femtosecond transient absorption spectroscopy (fs-TAS). Moreover, the built-in electric field and the differences in charge density based on density functional theory (DFT) calculations could provide the driving force for charge transfer. [Display omitted] • MOF/semiconductor heterojunction photocatalyst was firstly constructed. • Hydrogen-bonded combination between the –OOH groups and the –NH 2 group in MOF. • The significantly enhanced photocatalytic property of the H-T/M heterojunction for reducing Cr(VI). • The built-in electric field could provide the driving force for charge transfer. [ABSTRACT FROM AUTHOR]

Abstract: A series of Ag3PO4 and reduced graphite oxide sheets (RGOs) nanocomposites have been fabricated by a facile chemical precipitation approach in N,N-dimethylformamide (DMF) solvent without any hard/soft templates. The as-prepared Ag3PO4/RGOs composites were characterized by X-ray diffraction pattern (XRD), Fourier transform infrared spectra (FTIR), Raman spectroscopy, field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS). It is found that the nano-sized Ag3PO4 particles are deposited on the surfaces of RGOs. The Ag3PO4/RGOs nanocomposites exhibit enhanced photocatalytic activity for the photodegradation of organic methyl orange (MO) and methylene blue (MB) under visible light irradiation. The photocatalytic rate of Ag3PO4/2.1wt% RGOs nanocomposite is 3 and 2 times of that of pure Ag3PO4 nanoparticles for the degradation of MO and MB, respectively. Furthermore, the photocatalytic and structural stability of Ag3PO4 is greatly enhanced. It is suggested that RGOs can be used as protective coatings that partially inhibit the photocorrosion of Ag3PO4. Overall, this work could provide a new approach to the improvement not only in the photocatalytic activity but also the stability of photocorrosion catalysts. [Copyright &y& Elsevier]