Graphitic carbon nitride (g-C3N4) has become an attractive visible-light-responsive photocatalyst because of its semiconductor polymer compositions and easy-modulated band structure. However, the bulk g-C3N4 photocata...Graphitic carbon nitride (g-C3N4) has become an attractive visible-light-responsive photocatalyst because of its semiconductor polymer compositions and easy-modulated band structure. However, the bulk g-C3N4 photocatalyst has the low separation efficiency of photogenerated carriers and unsatisfied surface catalytic performance, which leads to poor photocatalytic performance. As for this, MgTi2O5 with high chemical stability, wide band gap and negative conduction band was used as a suitable platform for coupling with g-C3N4 to enhance charge separation and promoted the photoactivity. Different from common approaches, here, we propose an innovative method to construct g-C3N4/MgTi2O5 nanocomposites featuring “0 + 1 >1" magnification effect to improve g-C3N4 photocatalytic performance under visible light irradiation. Additionally, compositing metal oxides of MgTi2O5 with g-C3N4 has proven to be a proper strategy to accelerate surface catalytic reactions in g-C3N4, and the photoinduced carriers were modulated to maintain thermodynamic equilibrium, which convincingly promotes the photocatalytic activity. The photocatalytic performance of the nanocomposites was measured by hydrogen production and CO2 reduction under visible light. The developed g-C3N4/MgTi2O5 nanocomposites with a 5 wt.% MgTi2O5 exhibits the highest H2 and CO yield under visible light and excellent stability compare to the other MgTi2O5 contents in composites. According to surface photo-voltage spectra, electrochemical CO2 reduction, photoluminescence, etc. The superior performance can be related to an enhanced electron lifetime, the promoted charge transfer and the increased electronic separation property of g-C3N4. Our work provides an approach to overcome the defect of pure g-C3N4, which accesses to composite with the second component matched well.展开更多
An effective photocatalytic hydrogen production catalyst comprising MgTiO3/ MgTi2O5/TiO2 heterogeneous belt-junctions was prepared using magnesium ions by a thermally driven doping method. The tri-phase heterogeneous ...An effective photocatalytic hydrogen production catalyst comprising MgTiO3/ MgTi2O5/TiO2 heterogeneous belt-junctions was prepared using magnesium ions by a thermally driven doping method. The tri-phase heterogeneous junction was confirmed by X-ray powder diffraction （XRD）, transmission electron microscopy （TEM）, and high-resolution TEM （HRTEM）. The as-prepared MgTiOg/MgTi2OJ TiO2 heterojunctions exhibited a very high photocatalytic hydrogen production activity （356.1 mol·g0.1mgcat·h^-1） and an apparent quantum efficiency （50.69% at 365 nm） that is about twice of that of bare TiO2 nanobelts （189.4mol·g0.1mgcat·h^-1）. Linear sweep voltage and transient photocurrent characterization as well as analysis of the electrochemical impedance spectra and Mott-Schottky plots revealed that the high photocatalytic performance is caused by the one-dimensional structure, which imparts excellent charge transportation characteristic, and the MgTiO3/MgTi2O5/TiO2 tri-phase heterojunction, which effectively drives the charge separation through the inherent electric field. This titanate-based tri-phase heterogeneous junction photocatalyst further enriches the catalyst system for photocatalytic hydrogen production.展开更多
The suitable titanium slag composition with high titanium content for electric furnace smelting of vanadium titanomagnetite was investigated through thermodynamics and related phase diagram analysis.According to the t...The suitable titanium slag composition with high titanium content for electric furnace smelting of vanadium titanomagnetite was investigated through thermodynamics and related phase diagram analysis.According to the thermodynamic results,low-melting-point regions and MgTi2O5primary phase area in the phase diagrams,the suggested titanium slag composition for the present vanadium titanomagnetite metallized pellets should consist of50%TiO2,8%-12%MgO and13%Al2O3(mass fraction)with a binary basicity of0.8-1.2.Finally,the verified smelting experiments were conducted and successful separation of the molten iron from the titanium slag is obtained.The obtained vanadium-containing molten iron contains0.681%V and0.267%Ti,and the obtained titanium slag contains52.21%TiO2(mass fraction),in which MgTi2O5is the primary phase.The titanium resource in the final titanium slag production could be used to produce TiO2pigment by acid leaching methods.展开更多
基金supported by the National Natural Science Foundation of China (Nos.21871079 and 21501052).
文摘Graphitic carbon nitride (g-C3N4) has become an attractive visible-light-responsive photocatalyst because of its semiconductor polymer compositions and easy-modulated band structure. However, the bulk g-C3N4 photocatalyst has the low separation efficiency of photogenerated carriers and unsatisfied surface catalytic performance, which leads to poor photocatalytic performance. As for this, MgTi2O5 with high chemical stability, wide band gap and negative conduction band was used as a suitable platform for coupling with g-C3N4 to enhance charge separation and promoted the photoactivity. Different from common approaches, here, we propose an innovative method to construct g-C3N4/MgTi2O5 nanocomposites featuring “0 + 1 >1" magnification effect to improve g-C3N4 photocatalytic performance under visible light irradiation. Additionally, compositing metal oxides of MgTi2O5 with g-C3N4 has proven to be a proper strategy to accelerate surface catalytic reactions in g-C3N4, and the photoinduced carriers were modulated to maintain thermodynamic equilibrium, which convincingly promotes the photocatalytic activity. The photocatalytic performance of the nanocomposites was measured by hydrogen production and CO2 reduction under visible light. The developed g-C3N4/MgTi2O5 nanocomposites with a 5 wt.% MgTi2O5 exhibits the highest H2 and CO yield under visible light and excellent stability compare to the other MgTi2O5 contents in composites. According to surface photo-voltage spectra, electrochemical CO2 reduction, photoluminescence, etc. The superior performance can be related to an enhanced electron lifetime, the promoted charge transfer and the increased electronic separation property of g-C3N4. Our work provides an approach to overcome the defect of pure g-C3N4, which accesses to composite with the second component matched well.
基金Acknowledgements This work was supported by the National Natural Sdence Foundation of China （Nos. 21471050, 21501052 and 21473051）, the China Postdoctoral Science Foundation （No. 2015M570304）, the Postdoctoral Science Foundation of Heilongjiang Province （Nos. LBH-Ql1009 and LBH-TZ06019）, Heilongjiang Province Natural Science Foundation （Nos. ZD201301 and QC2015010）, and Harbin Technological Innovation Talent of Special Funds （No. RC2013QN017028）.
文摘An effective photocatalytic hydrogen production catalyst comprising MgTiO3/ MgTi2O5/TiO2 heterogeneous belt-junctions was prepared using magnesium ions by a thermally driven doping method. The tri-phase heterogeneous junction was confirmed by X-ray powder diffraction （XRD）, transmission electron microscopy （TEM）, and high-resolution TEM （HRTEM）. The as-prepared MgTiOg/MgTi2OJ TiO2 heterojunctions exhibited a very high photocatalytic hydrogen production activity （356.1 mol·g0.1mgcat·h^-1） and an apparent quantum efficiency （50.69% at 365 nm） that is about twice of that of bare TiO2 nanobelts （189.4mol·g0.1mgcat·h^-1）. Linear sweep voltage and transient photocurrent characterization as well as analysis of the electrochemical impedance spectra and Mott-Schottky plots revealed that the high photocatalytic performance is caused by the one-dimensional structure, which imparts excellent charge transportation characteristic, and the MgTiO3/MgTi2O5/TiO2 tri-phase heterojunction, which effectively drives the charge separation through the inherent electric field. This titanate-based tri-phase heterogeneous junction photocatalyst further enriches the catalyst system for photocatalytic hydrogen production.
文摘The suitable titanium slag composition with high titanium content for electric furnace smelting of vanadium titanomagnetite was investigated through thermodynamics and related phase diagram analysis.According to the thermodynamic results,low-melting-point regions and MgTi2O5primary phase area in the phase diagrams,the suggested titanium slag composition for the present vanadium titanomagnetite metallized pellets should consist of50%TiO2,8%-12%MgO and13%Al2O3(mass fraction)with a binary basicity of0.8-1.2.Finally,the verified smelting experiments were conducted and successful separation of the molten iron from the titanium slag is obtained.The obtained vanadium-containing molten iron contains0.681%V and0.267%Ti,and the obtained titanium slag contains52.21%TiO2(mass fraction),in which MgTi2O5is the primary phase.The titanium resource in the final titanium slag production could be used to produce TiO2pigment by acid leaching methods.
