Tian-Yu Liu

A novel yet simple strategy to fabricate visible light responsive C,N-TiO2/g-C3N4 heterostructures with significantly enhanced photocatalytic hydrogen generation

In this report, we first successfully designed and fabricated novel C,N co-doped titanium dioxide nanoparticles/graphite-like carbon nitrogen ultrathin nanosheets (C,N-TiO2 NPs/g-C3N4) heterostructures, wherein the C,N-TiO2 NPs were in situ grown on the porous g-C3N4 ultrathin nanosheets (NSs) by a simple one-pot solvothermal route with the assistance of concentrated nitric acid. The resulting C,N-TiO2 NPs/g-C3N4 nanocomposite photocatalysts were systematically characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, transient photocurrent–time (I–t) curves and electrochemical impedance spectroscopy (EIS) Nyquist plots. The photocatalytic ability was evaluated by photocatalytic water splitting for hydrogen evolution. These studies indicate that C,N-TiO2 NPs/g-C3N4 composites exhibit superior ability for hydrogen generation compared to single C,N-TiO2 NPs and pure g-C3N4 NSs under visible light illumination. The optimal composites with 3 wt% C,N-TiO2 NPs/g-C3N4 showed the highest hydrogen evolution rate of 39.18 μmol g−1 h−1, which is about 10.9 and 21.3 times higher than those of C,N-TiO2 NPs and pure g-C3N4 NSs, respectively. The improved photocatalytic H2 evolution can be attributed to improved optical absorption and the lengthening lifetime of charge carrier pairs as a result of the C,N elemental codoping and the construction of intimate heterogeneous interfaces. This simple and feasible method for the fabrication of highly-efficient visible light responsive catalysts provides a great applied potential in energy generation.

Hierarchical CdIn2S4 microspheres wrapped by mesoporous g-C3N4 ultrathin nanosheets with enhanced visible light driven photocatalytic reduction activity

In this investigation, a series of hierarchical CdIn2S4/g-C3N4 nanocomposites were firstly synthesized by a facile one-pot hydrothermal strategy, wherein the mesoporous g-C3N4 nanosheets were in-situ self-wrapped onto CdIn2S4 nanosheets. Systematic characterization by XRD, FT-IR, UV-vis DRS, SEM, TEM, HAAF-STEM, XPS, photoelectrochemical tests were employed to analyze the phase structure, chemical composition, morphology and photocatalytic mechanism. The application, including photo-redox reaction and photocatalytic water splitting, were used to estimate the photocatalytic activity of as-obtained CdIn2S4/g-C3N4 nanocomposites. The results indicate that CdIn2S4/g-C3N4 heterostructures exhibit more efficient improvement of the photocatalytic performances towards photo-reduction of 4-NA to corresponding 4-PDA and photocatalytic H2 generation from water splitting than these counterparts as results of construction of intimate interfacial contact, which would promote the separation of photo-generated holes and electrons. Meanwhile, benefitting from the excellent surface wrap, the CdIn2S4/g-C3N4 nanocomposites possess notable enhanced photocatalytic stability. This research may provide a promising way to fabricate highly efficient photocatalysts with excellent stability and expand the application of CdIn2S4 in fine chemical engineering.

One-pot hydrothermal route to synthesize the ZnIn2S4/g-C3N4 composites with enhanced photocatalytic activity

Heterogeneous ZnIn2S4/g-C3N4 hybrid composites, as highly efficient visible-light-driven photocatalysts, were designed and fabricated by a simple one-step hydrothermal route for the first time, wherein the cubic ZnIn2S4 nanoparticles were in situ immobilized on the surface of porous g-C3N4 nanosheets (NSs). The resultant composites exhibit efficient photocatalytic activities, excellent photo-stability, and versatile photocatalytic abilities towards organic dye degradation, Cr(VI) reduction, and water splitting for H2 evolution. The significant enhancement of photocatalytic activity is attributed to the effective separation of photo-generated charge carrier pairs based on the construction of close heterogeneous interface and well-matched band structure, which can obviously lengthen the life span of holes and electrons pairs. Besides, the effective charge transfer from cubic ZnIn2S4 to ultrathin g-C3N4 NSs was confirmed by photoluminescence spectra, transient photocurrent–time (I–t) curves and electrochemical impedance spectroscopy Nyquist plots. This research provides a new sight in designing the highly efficient visible light responsive photocatalysts for environmental remediation and energy production.

Synthesis of homogeneous one-dimensional NixCd1−xS nanorods with enhanced visible-light response by ethanediamine-assisted decomposition of complex precursors

Abstract A route to fabricate the homogeneous one-dimensional (1D) NixCd1−xS nanorods (NRs) photocatalysts is designed with ethanediamine-assisted decomposition of NixCd1−x (DDTC)2 complex precursors. This route developed NixCd1−x (DDTC)2 complex precursors by co-precipitation method at room temperature condition. The effects of Ni2+ doped into CdS lattice on the length and photocatalytic performance of the NixCd1−xS NRs have been investigated in detail. It is found that doping of Ni2+ significantly affects the aspect ratio of 1D NixCd1−xS NRs. With the increasing doping concentration of Ni2+, the length of as-obtained NixCd1−xS NRs becomes shorter. In addition, their photocatalytic activity was evaluated by the degradation of Rhodamine B dye as a probe reaction under visible-light irradiation. The results show that the optimal Ni2+ addition shows efficient photocatalytic performance and excellent photo stability, which may result from Ni2+ lattice doping. A tentative photocatalytic mechanism of 1D NixCd1−xS NRs is proposed for further explanation of photocatalytic performance.

Biomolecule-assisted solvothermal synthesis and enhanced visible light photocatalytic performance of Bi2S3/BiOCl composites

Novel Bi2S3/BiOCl photocatalysts were successfully synthesized via a facile biomolecule-assisted solvothermal method and biomolecule L-cysteine was used as the sulfur source. The structures, morphology, and optical properties of the synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (DRS). The presence of Bi2S3 in the Bi2S3/BiOCl composites could not only improve the optical properties but also enhance the photocatalytic activities for the degradation of Rhodamine B (RhB) under visible-light irradiation (λ > 420 nm) as compared with single Bi2S3 and BiOCl. Especially, the sample displayed the best performance of the photodegradation when the feed molar ratio of BiCl3 and L-cysteine was 2.4:1, which was about 10 times greater than that of pure BiOCl. The enhanced photocatalytic activities could be ascribed to the effective separation of photoinduced electrons and holes and the photosensitization of dye. Moreover, the possible photodegradation mechanism was also proposed, and the results revealed that the active holes (h+) and superoxide radicals (•O2−) were the main reactive species during photocatalytic degradation.