Copper Semiconductor Optical Catalyst And Its Photocatalytic Hydrogen Production Activity

CuO, CuO/ZrO2 and Y2CU2O5 photocatalysts were successfully synthesized via different methods.The as-obtained photocatalysts were modified by noble metal depositing, composite with TiO2 and NiO loading.Thermogravimetry and differential thermal analysis (TG/DTA), X-ray diffraction (XRD),transmission electron microscopy (TEM), scanning electron microscopy(SEM), and ultraviolet visible diffuse reflectance absorption spectra (UV-Vis DRS) were employed to characterize the as-synthesized samples.It is the first time that the photocatalytic activity of the as-obtained photocatalysts was evaluated based on the photocatalytic H2 evolution under simulated sunlight irradiation.The influencing factors of photocatalytic activity and durability of the photocatalyst were also investigated.There can afford some experimental data and theoretical references for enriching the research on copper semiconductors.(1)CuO photocatalysts were successfully fabricated by different methods.The photocatalytic activity of the as-obtained CuO was investigated under simulated sunlight irradiation. We also studied the mechanism of photocatalytic reaction.The results demonstrated that the highest photocatalytic activity of the as-obtained CuO can be achieved when the preparation method is thermal decomposition, the calcination temperature is 1000℃,oxalic acid is used as the sacrificial reagent, and the concentration is 0.05 mol·L-1.The H2 evolution rate is as high as up to 2.48 mmol·h-1·g-1.Noble metal depositing can greatly improve the photocatalytic activity of the as-obtained CuO.The photocatalytic activity of Ag depositing photocatalysts prepared by hydrogen reduction method was better than prepared by photoreduction method. The bestest Ag depositing content is 2 wt.%,and the highest H2 evolution rate is up to 2.98 mmol·h-1·g-1.When the photocatalyst was deposited by different noble metals, the results show that Pt is the bestest noble metal for improving the photocatalytic H2 evolution activity, and the highest H2 evolution rate is up to 3.61 mmol·h-1·g-1 with 2 wt.% deposited Pt. However, CuO is unstable in the oxalic acid solution.(2) CuO/ZrO2 composite photocatalysts were synthesized via three approaches, solid state reaction, co-precipitation method, as well as sol-gel technique.All of them exhibited high activity for H2 evolution. Under the simulated sunlight irradiation, when the sample was synthesized by sol-gel technique, the mole fraction of CuO:ZrO2 is 40%, the alcination temperature is 900℃and the alcination atmosphere is air, the bestest photocatalytic H2 evolution activity is up to 2.41 mmol·h-1·g-1. The photocatalytic H2 evolution activity of CuO/ZrO2 is better than CuO/TiO2 composite photocatalyst. And CuO/ZrO2 composite photocatalyst is more stable than CuO photocatalyst in the oxalic acid solution.(3)The photocatalytic H2 evolution activity of Y2Cu2O5 was also influenced by many factors. Under the simulated sunlight irradiation, the highest photocatalytic H2 evolution activity of Y2Cu2O5 was achived at 3.78 mmol·h-1·g-1 when the sample was synthesized by solid state reaction, oxalic acid is used as the sacrificial reagent, the concentration of photocatalyst is 0.8 g·L-1.The activity of Y2Cu205 is better than CuO and CuO/ZrO2.When Pt was deposited on Y2Cu205 photocatalyst by hydrogen reduction method and the depositing content was 1 wt%, the bestest photocatalytic H2 evolution activity is up to 4.12 mmol·h-1·g-1. The activity of NiO/Y2Cu2O5 photocatalyst is influenced dramatically by sacrificial reagent.The activity of Y2Cu2O5 is decreased by NiO loading when oxalic acid acted as the sacrificial reagent. However, when Na2S was used as the sacrificial reagent, NiO loading can significant improve the photocatalytic H2 evolution activity of Y2Cu2O5.Because the p-n heterojunction was obtained, composite with TiO2 can also improve the activity of Y2Cu2O5.The bestest photocatalytic H2 evolution activity Y2Cu205-TiO2 heterojunction photocatalyst is 4.35 mmol·h-1·g-1 when Y2Cu205-Ti02 was synthesized by sol-gel technique and the amount of TiO2 is 30%.But Y2Cu2O5 is also unstable in the oxalic acid solution.