In the face of the increasingly serious energy crisis and environmental pollution,it is important to develop durable and efficient photocatalytic materials for hydrogen production from water splitting.The MXene@TiO2 of high-performance MXene-based photocatalytic materials (M@T) is synthesized by a one-step hydrothermal method at 160 ℃ using Ti3C2 as the titanium source and TiO2@Ti3C2 derivatives synthesized by a one-step hydrothermal method.Co-MoS2-x O y (C-M) is prepared by sodium molybdate dihydrate (Na2MoO4·2H2O) as molybdenum source,CH3CSNH2 as sulfur source,and cobalt nitrate hexahydrate (Co(NO3)2?6H2O) as cobalt source.M@T/C-M composites are prepared at the ratios of m(M@T)/m(C-M) of 1∶1,1∶2,1∶3 and 1∶4.The structure and surface morphology of different composite systems are characterized by XRD,SEM,XPS,UV-vis,etc.At the same time,the photocatalytic degradation of methylene blue (MB),an organic pollutant in water,is tested by using xenon lamp as the light source.The results show that the M@T/C-M composites are successfully synthesized,and the light absorption range is increased to the visible region.The degradation rate of M@T/C-M(1∶3) in 20 mg/L MB solution is as high as 92.6%.The photodegradation of MB by M@T/C-M photocatalyst is mainly driven by ?OH and ?O 2 - radicals.
The use of solar photocatalytic degradation of pollutants is one of the most promising technologies to solve water pollution problems and achieve solar energy conversion. By changing the amount of g-C3N4 added, g-C3N4/Co3O4 catalysts with different g-C3N4 mass fractions are prepared based on the calcination method with cobalt nitrate hexahydrate (Co（NO3)2-6H2O) and urea (NH4CNO) as raw materials. The samples are analyzed and characterized using X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and ultraviolet visible absorption spectroscopy （UV-vis DRS）. To speculate on the active species of the catalyst, capture agent experiments are conducted on it. The results indicate that the synergistic effect between g-C3N4 and Co3O4 can improve the transfer and separation efficiency of charge carriers at the interface between the two phases. Under visible light, the degradation effect of 10% g-C3N4/Co3O4 is the best, with a degradation rate of 66.50%, which is higher than the degradation effect of single Co3O4 （degradation rate of 35.90%）. The active species of the catalyst are mainly superoxide radicals（·O2-） and holes（h+）. After compounding with g-C3N4, the drawbacks of Co3O4 electron hole pair, such as too fast recombination and a deficient energy level structure, are improved, providing ideas for the degradation of organic pollutants in the future.
Heterogeneous Mn3O4/CuMnO2 catalyst CMO-A is prepared by a one-step hydrothermal method using cupric chloride dihydrate and manganese chloride tetrahydrate as raw materials.The composition of the samples prepared at different temperatures is analyzed by X-ray diffraction analysis.Using mercury lamp as light source and 50 mg/L Rhodamine B(RhB) solution as contaminant model,the photo-Fenton reaction performance of the prepared CMO-A sample is tested.The results show that CMO-150 has the best degradation effect on RhB solution when the reaction temperature is 150 ℃,and the degradation rate reaches 98.01% when the reaction time is 15 min.The optimal reaction conditions and cyclic stability of CMO-150 catalyst are investigated.The experimental results show that the optimal reaction conditions are 0.2 mol/L H2O2,50 mg CMO-150 catalyst,50 mg/L RhB solution and pH=3.0.After 5 cycles,the degradation rate only decreases by 22.24% at 15 min.The main active species in the reaction is hydroxyl radical (·OH) through the sacrificial agent experiment,and the reaction mechanism is explored by combining with the control experiment.
The BaTiO3?TiO2 composites were prepared by using hydrate barium hydroxide (Ba(OH)2·8H2O) and titanium dioxide (TiO2) as raw materials with soft chemical hydrothermal method at 120 ℃ and different Ba/Ti molar ratios.The structure of the prepared composites with different Ba/Ti molar ratios was analyzed by X?ray diffraction (XRD),scanning electron microscopy (SEM),and UV?visible absorption spectroscopy (UV?Vis),the degradation effect of the complex on the simulated degradation pollutant,rhodamine B (RhB) was investigated.The results indicate that the BaTiO3?TiO2 composites obtained at a Ba/Ti molar ratio of 0.50 have an excellent catalytic effect for the degradation of rhodamine B (RhB) during the simulation of dye wastewater degradation.Meanwhile,more active sites formed at the Ba/Ti molar ratio of 0.50, which facilitated the photocatalytic reaction.
The spherical hexagonal phase tungsten oxide (h?WO3) was synthesized by precipitation method. Then a series of hexagonal/monoclinic WO3(h/m?WO3) phase junction photocatalysts were controllable fabricated by regulating the phase transition process from hexagonal to monoclinic phase. The crystal phase structure and phase composition, particle size and specific surface area of these WO3 catalysts were characterized by X?ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area (BET). The experimental results of photocatalytic O2 evolution show that compared with the pure hexagonal phase WO3, the h/m?WO3 with suitable crystal phase composition exhibits remarkable photocatalytic performance. Based on the band positions of hexagonal and monoclinic phases, the surface photovoltage (SPV) characterization results show that the formation of h/m?WO3 phase junction significantly promotes the efficient separation of photogenerated electrons and holes on the surface of the catalyst, and then improves the photocatalytic activity of WO3 catalyst.
Ppb amount of SO2 in air will react with cathode material of solid oxide fuel cell, inducing decrease of the cell/stack performance as one of the most effective factors.The sulfur poisoning behavior of (La0.6Sr0.4) (Co0.2Fe0.8)O3(LSCF) and A?site deficient (La0.6Sr0.4)0.85(Co0.2Fe0.8)O3(LSCF85) was investigated after exposure to 30 μg/g SO2 at 800 ℃ for 50 h.The products of the reaction were characterized by XRD,SEM and EDX to evaluate the effect of A?site defects on the sulfur poisoning behavior of perovskite ferrite based solid oxide fuel cell cathode materials. It was found that A?site defect in LSCF85 can suppress the chemical reaction between LSCF based cathode and SO2. It was ascribed to the low Sr reaction activity with SO2 caused by the existence of A?site defect.
