MoS2/Zn3In2S6 composite photocatalysts for enhancement of visible light-driven hydrogen production from formic acid

Enhancing the separation efficiency of photogenerated carriers is propitious for the promotion of photocatalytic hydrogen production from formic acid decomposition.Herein,MoS2/Zn3In2S6(MoS2/ZIS6)composite photocatalysts containing varying mass percentages of MoS2 were obtained by a straightforward synthetic method.The results confirmed that MoS2,as a cocatalyst,markedly promoted the photogenerated charge separation efficiency and visible light-driven hydrogen production activity of ZIS6(λ>400 nm).Specifically,the as-prepared 0.5%MoS2/ZIS6 photocatalyst exhibited the highest photocatalytic hydrogen production rate(74.25μmol·h^-1),which was approximately 4.3 times higher than that of ZIS6(17.47μmol·h^-1).The excellent performance of the 0.5%MoS2/ZIS6 photocatalyst may be due to the fact that MoS2 has a low Fermi energy level and can thus enrich photogenerated electrons from ZIS6,and furthermore reduce H+derived from formic acid,to form hydrogen.The structure and morphology of the MoS2/ZIS6 photocatalysts and the reactive species were determined by X-ray diffraction,transmission electron microscopy,and field emission scanning electron microscopy,among others;a plausible mechanistic rationale is discussed based on the results.

Self-assembly synthesis of S-scheme g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) for photocatalytic degradation of norfloxacin and bisphenol A

To realize the high-efficiency photodegradation of antibiotics,a novel S-scheme heterojunction photocatalyst g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) was proposed and successfully prepared in this work.The 10%g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) heterojunction exhibits the highest degradation rate of norfloxacin(NOR)and bisphenol A(BPA).The degradation rate of NOR on 10%g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) is about 1.38 and 2.33 times higher than that of pure Bi_(8)(CrO_(4))O_(11) and g-C_(3)N_(4),respectively.Further,the degradation rate of BPA over 10%g-C_(3)N_(4)/Bi_(8)(CrO_(4))O_(11) heterojunction is bout 1.35 and 9.11 times higher than that of pure Bi_(8)(CrO_(4))O_(11) and g-C_(3)N_(4),respectively.The formation of S-scheme heterojunction facilitates the separation of photogenerated electron-hole pairs and reduces the recombination of charge carriers,which was confirmed by photocurrent,electrochemical impedance spectroscopy,steady-state and time-resolved transient photoluminescence spectrum,etc.The in-situ X-ray photoelectron spectroscopy,radical trapping experiments and electron paramagnetic resonance results demonstrate that the charge transfer is in accord with S-scheme mechanism.

A new phosphidation route for the synthesis of NiPx and their cocatalytic performances for photocatalytic hydrogen evolution over g-C3N4

Ni-based phosphides(NiPx)composed of earth-abundant elements are promising cocatalysts to replace noble metals for photocatalytic H2 evolution reaction(HER).A safe,energy-saving,and compositioncontrollable synthesis of NiPx is still highly desired.A facile and mild solvothermal process was developed for the first time for selective synthesis of a series of NiPx,including Ni,Ni12P5,Ni2P/Ni12P5,Ni/Ni2P and Ni2P,through controlling the dosage of NaBH4 and NaH2PO2.The phosphidation process was mainly composed of(1)a sequential reduction of Ni2+to Nj0 and(H2PO2)-to P(around the formed Ni0)triggered by NaBH4,and(2)a final phosphidation between Nj0 and the in situ generated P atoms.The photocatalytic HER performance of g-C3N4 can be substantially improved with the decoration of NiPx(3 wt%)as the separation of photoinduced charge carriers can be promoted and some active sites with low over-potential for HER can be introduced.The cocatalytic efficiency of NiPx is mainly determined by P content.Ni2P with a high ratio of P consequently exhibits the highest HER performance(215.1 umol g-1 h-1),which is almost six times higher than that of the pristine g-C3N4(35.6 umol g-1 h-1).Thus,as for the cocatalyst based on Ni phosphides,Ni2P is the preferable crystal phase and more efforts should be devoted to Ni2P to further optimize its structure,texture,and morphology in future works.

A Novel CdS/g-C3N4 Composite Photocatalyst： Preparation, Characterization and Photocatalytic Performance with Different Reaction Solvents under Visible Light Irradiation

CdS/graphtic carbon nitride （CdS/g-C3N4） hybrid materials were fabricated by thermal polymerization and hy- drothermal methods using Cd（CH3COO）2-2H2O, thioacetamide, and melamine as precursors. The structural and op- tical properties of the as-synthesized samples were investigated by X-ray powder diffraction, UV-Vis diffuse reflec- tance spectroscopy, scanning electron microscopy, transmission electron microscopy, etc. A coupled system toward the selective oxidation of benzyl alcohol to benzaldehyde and the reduction of nitrobenzene into aniline was used to estimate the photocatalytic performance of CdS/g-C3N4 composite photocatalysts under visible light illumination. Results indicate that the CdS/g-C3N4 sample exhibits an outstanding photocatalytic performance for selective oxida- tion of benzyl alcohol and reduction of nitrobenzene. Meanwhile, benzotrifluoride is the best reaction medium among the screened solvents. Further research demonstrates that the selective oxidation of benzyl alcohol to ben- zaldehyde is induced by the photoexcited holes and the reduction of nitrobenzene into aniline is triggered by the photoexcited electrons. Additionally, the catalyst can be recycled several times without noticeable deactivation.

Recent advances in special morphologic photocatalysts for NO_(x)removal

The significant increase of NO_(x)concentration causes severe damages to environment and human health.Light-driven photocatalytic technique affords an ideal solution for the removal of NO_(x)at ambient conditions.To enhance the performance of NO_(x)removal,1D,2D and 3D photocatalysts have been constructed as the light absorption and the separation of charge carriers can be manipulated through controlling the morphology of the photocatalyst.Related works mainly focused on the construction and modification of special morphologic photocatalyst,including element doping,heterostructure constructing,crystal facet exposing,defect sites introducing and so on.Moreover,the excellent performance of the photocatalytic NO_(x)removal creates great awareness of the application,which has promising practical applications in NO_(x)removal by paint(removing NO_(x)indoor and outdoor)and pavement(degrading vehicle exhausts).For these considerations,recent advances in special morphologic photocatalysts for NO_(x)removal was summarized and commented in this review.The purpose is to provide insights into understanding the relationship between morphology and photocatalytic performance,meanwhile,to promote the application of photocatalytic technology in NO_(x)degradation.