The violet polycrystalline (NH4)5[(VO)6(CO3)4(OH)9]·10H2O(NVCO) was simply sy nthesized by solution reaction using V2O5, HCl, N2H4·2HCl and NH4HCO3 as the st arting materials. The results of TGA and DTA of N...The violet polycrystalline (NH4)5[(VO)6(CO3)4(OH)9]·10H2O(NVCO) was simply sy nthesized by solution reaction using V2O5, HCl, N2H4·2HCl and NH4HCO3 as the st arting materials. The results of TGA and DTA of NVCO under H2(99.999%) atmosphe re show that V2O3 forms at 620℃. The data of TG/DTG and DTA of NVCO under N2(99 .999%) atmosphere indicate that VO2 forms at 367℃and crystallizes at 390℃. In air atmosphere, the TG/DTG and DTA of NVCO show that V2O5 forms at 354℃, cryst allizes at 366℃and melts at 664℃. The three thermolysis processes of NVCO show that a large amount of H2O, CO2 and NH3 gases fast releases during the thermoly sis of NVCO, causing that the particles of the materials split and atomize stron gly, thus to obtain V2O3, VO2 and V2O5 nano-powders finally. According to the a bove of thermoanalytical results, V2O3, VO2 and V2O5 powders were prepared respe ctively under H2, N2 and oxygen in a tube furnace. Chemical analysis and XRD exp eriments of the powders identify that pure V2O3 is obtained at 800℃for 0.5h und er H2 atmosphere; crystalline VO2 is obtained at 480℃for 0.5h in N2; amorphous VO2 is obtained at 350℃for 20min under N2 atmosphere, this has been first repor ted to prepare amorphous VO2 powder so far; pure V2O5 is obtained at 400℃for 10 min under oxygen. From the micrographs of the powders, the particle size of the V2O3, the crystalline VO2 or the V2O5 powders is 35nm, 24nm or < 40nm, respectiv ely. Above-mentioned results prove that NVCO is a good precursor for preparatio n of pure V2O3, VO2 and V2O5 nano-powders under mild conditions.展开更多
A two‐step photocatalytic water splitting system,termed a“Z‐scheme system”,was achieved using Zn‐doped g‐C3N4for H2evolution and BiVO4for O2evolution with Fe2+/Fe3+as a shuttle redox mediator.H2and O2were evalua...A two‐step photocatalytic water splitting system,termed a“Z‐scheme system”,was achieved using Zn‐doped g‐C3N4for H2evolution and BiVO4for O2evolution with Fe2+/Fe3+as a shuttle redox mediator.H2and O2were evaluated simultaneously when the doping amount of zinc was10%.Moreover,Zn‐doped(10%)g‐C3N4synthesized by an impregnation method showed superior active ability to form the Z‐scheme with BiVO4than by in‐situ synthesis.X‐ray diffraction,UV‐Vis spectroscopy,scanning electron microscopy,and X‐ray photoelectron spectroscopy were used to characterize the samples.It was determined that more Zn?N bonds could be formed on the surface of g‐C3N4by impregnation,which could facilitate charge transfer.展开更多
文摘The violet polycrystalline (NH4)5[(VO)6(CO3)4(OH)9]·10H2O(NVCO) was simply sy nthesized by solution reaction using V2O5, HCl, N2H4·2HCl and NH4HCO3 as the st arting materials. The results of TGA and DTA of NVCO under H2(99.999%) atmosphe re show that V2O3 forms at 620℃. The data of TG/DTG and DTA of NVCO under N2(99 .999%) atmosphere indicate that VO2 forms at 367℃and crystallizes at 390℃. In air atmosphere, the TG/DTG and DTA of NVCO show that V2O5 forms at 354℃, cryst allizes at 366℃and melts at 664℃. The three thermolysis processes of NVCO show that a large amount of H2O, CO2 and NH3 gases fast releases during the thermoly sis of NVCO, causing that the particles of the materials split and atomize stron gly, thus to obtain V2O3, VO2 and V2O5 nano-powders finally. According to the a bove of thermoanalytical results, V2O3, VO2 and V2O5 powders were prepared respe ctively under H2, N2 and oxygen in a tube furnace. Chemical analysis and XRD exp eriments of the powders identify that pure V2O3 is obtained at 800℃for 0.5h und er H2 atmosphere; crystalline VO2 is obtained at 480℃for 0.5h in N2; amorphous VO2 is obtained at 350℃for 20min under N2 atmosphere, this has been first repor ted to prepare amorphous VO2 powder so far; pure V2O5 is obtained at 400℃for 10 min under oxygen. From the micrographs of the powders, the particle size of the V2O3, the crystalline VO2 or the V2O5 powders is 35nm, 24nm or < 40nm, respectiv ely. Above-mentioned results prove that NVCO is a good precursor for preparatio n of pure V2O3, VO2 and V2O5 nano-powders under mild conditions.
基金supported by the National Natural Science Foundation of China (21773153)~~
文摘A two‐step photocatalytic water splitting system,termed a“Z‐scheme system”,was achieved using Zn‐doped g‐C3N4for H2evolution and BiVO4for O2evolution with Fe2+/Fe3+as a shuttle redox mediator.H2and O2were evaluated simultaneously when the doping amount of zinc was10%.Moreover,Zn‐doped(10%)g‐C3N4synthesized by an impregnation method showed superior active ability to form the Z‐scheme with BiVO4than by in‐situ synthesis.X‐ray diffraction,UV‐Vis spectroscopy,scanning electron microscopy,and X‐ray photoelectron spectroscopy were used to characterize the samples.It was determined that more Zn?N bonds could be formed on the surface of g‐C3N4by impregnation,which could facilitate charge transfer.
