Chemical Engineering Journal ( IF 15.1 ) Pub Date : 2018-07-17 , DOI: 10.1016/j.cej.2018.07.115 Juan Yang , Jingyi Hao , Siyu Xu , Jun Dai , Yan Wang , Xinchang Pang
In this study, Nb2O5 nanorods/graphene composites (NbO NRs/GR) are prepared by one-pot alkaline hydrothermal process, utilizing the new roles of graphene oxide (GO) as the structure-directing and morphology-controlling agent for the growth of NbO NRs. Compared to blank NbO, NbO/GR composites exhibit significantly improved photocatalytic activity for 4-CP degradation under visible-light irradiation, although 4-CP and NbO do not absorb visible light themselves. The in-situ formation of surface complexes between 4-CP and NbO and the subsequent charge transfer based on LMCT mechanism can be responsible for the visible photocatalytic activity. And meanwhile, the photoelectrons transferred to GR surface from in-situ formed complex (NbO/4-CP) via NbO NRs can initiate the synergistic Cr(VI) reduction. The GR contents and NbO crystalline phase have great effects on the photocatalytic activity of NbO/GR composites toward simultaneous 4-CP degradation and Cr(VI) reduction. The amorphous NbO/GR composite with 4.0 wt% GR (NbO-400/GR-4.0%) shows the highest photocatalytic activity. The influences of various experimental conditions (including the surface fluorination of NbO/GR, the initial concentrations of 4-CP and Cr(VI), pH, reaction atmosphere, and adding radical scavengers) on the visible photocatalytic activities are investigated in detail. According to the catalytic activity, UV-vis DRS and FT-IR spectra of NbO/4-CP or NbO/GR/4-CP, and photocurrent response in aqueous 4-CP solution, the formation of the surface complex is evidenced and the visible-light catalytic mechanism based on LMCT process is proposed.
中文翻译:
一锅合成无定形Nb 2 O 5纳米棒/石墨烯异结构复合材料上的可见光驱动的4-CP光催化降解和Cr(VI)的协同还原
在这项研究中,Nb 2 O 5纳米棒/石墨烯复合材料(NbO NRs / GR)是通过一锅法碱性水热法制备的,利用氧化石墨烯(GO)作为NbO NRs生长的结构导向和形态控制剂的新作用。与空白NbO相比,NbO / GR复合材料在可见光照射下对4-CP降解表现出显着改善的光催化活性,尽管4-CP和NbO本身并不吸收可见光。4-CP和NbO之间表面复合物的原位形成以及随后基于LMCT机理的电荷转移可能是可见光催化活性的原因。同时,通过NbO NRs从原位形成的配合物(NbO / 4-CP)转移到GR表面的光电子可以引发协同Cr(VI)还原。GR含量和NbO晶相对NbO / GR复合材料同时进行4-CP降解和Cr(VI)还原的光催化活性有很大影响。具有4.0 wt%GR(NbO-400 / GR-4.0%)的无定形NbO / GR复合材料显示出最高的光催化活性。详细研究了各种实验条件(包括NbO / GR的表面氟化,4-CP和Cr(VI)的初始浓度,pH,反应气氛以及添加自由基清除剂)对可见光催化活性的影响。根据NbO / 4-CP或NbO / GR / 4-CP的催化活性,UV-vis DRS和FT-IR光谱以及4-CP水溶液中的光电流响应,可以证明表面络合物的形成,并且提出了基于LMCT工艺的可见光催化机理。