可见光催化材料纳米氧氮化钽的制备及分解水制氢性能

发布时间：2018-03-28 07:31

  本文选题：可见光　切入点：催化　出处：《东华大学》2015年硕士论文

【摘要】：太阳能光催化分解水制氢是21世纪人类从根本上解决日益严峻的能源与环境问题较为理想的途径之一，已引起了各国研究者的高度关注。然而，目前所研究的光催化材料大都只能在紫外光下有光催化响应。由于N2p轨道能级比O2p轨道能级高，多数过渡金属氧化物氮化为氧氮化物后，在可见光区呈现较强的吸收能力，是一种潜在的具有可见光响应能力的光催化材料。近年来，开发和研制在可见光区具有高活性的过渡金属氧氮化物光催化剂成为光催化的研究前沿。本论文以过渡金属氧化物为原料，通过氮化反应制备出具有窄能隙的、可见光响应的光催化剂纳米TaON，论文的主要内容有： 采用高温气固相反应，以Ta2O5为原料，通过氮化反应制备TaON。采用X-射线衍射（XRD）分析、场发射扫描电子显微镜（FESEM）、紫外－可见(UV-VIS)漫反射光谱分析、氮气吸附-脱附分析等测试手段对所制备的光催化剂进行了表征，结果表明：在反应温度为850℃，氨气流量为90ml/min，氮化10h可制得纯相的TaON。通过改变催化剂的形貌，增大比表面积，进而提高催化剂的活性，制得了细颗粒TaON、多孔TaON及纤维状TaON中，其中细颗粒TaON具有最大的比表面积，达到109.2m2/g，光催化活性最高，将初始浓度为50PPm的亚甲基蓝溶液在可见光照射下120min，，浓度降低了96%，具有最好的光催化活性。 为降低TaON的缺陷密度，在细颗粒Ta2O5粉体表面复合一层ZrO2纳米颗粒，氮化得到了ZrO2/TaON复合材料。界面处的钽离子与ZrO2相互作用，有效抑制了低价钽离子的形成。为了进一步提高ZrO2/TaON复合光催剂的活性，于ZrO2/TaON的表面负载RuO2为助催化剂，用XRD、SEM和TEM等表征，证明在TaON表面成功包覆了ZrO2和RuO2颗粒，用光电流及光催化制氢反应器评价了复合材料的光催化性能，在RuO2含量为2wt%时活性最高，产氢速率为5umol/h。 以钽粉为原料，采用水热法制备了无定型的Ta2O5，经氮化、氮化后再氧化得到高活性的γ-TaON，并与CdS复合形成异质结结构。为抑制CdS在水溶液中的光腐蚀，在其表面包覆一层ZnS。采用X射线衍射仪（XRD）、场发射扫描电子显微镜（FESEM）和透射电子显微镜（TEM）对复合材料进行表征，表明ZnS/CdS颗粒成功的包覆在γ-TaON光催化剂的表面。光电流结果表明其活性大幅提高。在可见光照射下，ZnS/CdS/γ-TaON复合光催化剂在甲酸溶液中表现出最高的活性；当ZnS/CdS的含量为20wt%时，产氢速率达到了20umol/h。
[Abstract]:Photocatalytic decomposition of water for hydrogen production by solar energy is one of the ideal ways to solve the increasingly serious energy and environmental problems in the 21st century, which has attracted the attention of researchers all over the world. At present, most of the photocatalytic materials studied can only have photocatalytic response under ultraviolet light. Because the N 2p orbital energy level is higher than that of O 2p orbital energy level, most transition metal oxides nitrided into oxygen nitride, showing strong absorption ability in the visible light region. Is a potential photocatalytic material with visible light response. In recent years, In this paper, transition metal oxide photocatalysts with high activity in visible light region have been developed and developed. In this paper, transition metal oxides were used as raw materials to prepare transition metal oxide photocatalysts with narrow energy gap. Visible light responsive photocatalyst nano-TaON, the main contents of the paper are:. TaON was prepared by nitriding reaction with high temperature gas-solid reaction and Ta2O5. The results were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), UV-Vis (UV-VIS) diffuse reflectance spectroscopy. The photocatalysts were characterized by nitrogen adsorption-desorption analysis. The results showed that the pure phase TaON could be obtained by changing the morphology of the catalyst and increasing the specific surface area at 850 鈩

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