文献速递|南昌航空大学邹建平教授ACB:光诱导加速异质FeNi-MOFs中Fe3+/Fe2+循环以促进PDS活化降解有机污染物
第一作者:Dengke Wang
通讯作者:邹建平 教授
通讯单位:南昌航空大学环境与化学工程学院
DOI:10.1016/j.apcatb.2022.122054
Fe2+在Fe基异相催化剂中的缓慢再生速率限制了其在基于过硫酸盐的高级氧化工艺(PS-AOPs)中的广泛应用。为了应对这一挑战,本研究制备了具有异原子金属节点的Fe-嵌入Ni基金属有机框架(FeNi-MOFs),并将其用于过硫酸盐活化,构建了高效的PS-AOPs。光谱分析和密度泛函理论(DFT)计算表明,在光照下,配体-金属电荷转移和相邻Ni中心的极化加速了Fe3+/Fe2+在FeNi-MOFs中的氧化还原循环,从而促进了Fe2+的回收,Fe3+/Fe2+循环效率大于58%。因此,FeNi-MOFs在过二硫酸盐活化方面具有显著的性能,其比活性高于对照Ni-MOFs/Fe3+和目前报道的先进催化剂。该研究为在完全异构体系中加速Fe3+/Fe2+循环以实现过硫酸盐活化提供了新途径,同时也凸显了MOFs在设计用于PS-AOPs的高性能Fe基催化剂方面的巨大潜力。
为了验证这一假设,制备了铁包合镍基MOFs(FeNi-MOFs),并将其作为稳定的催化剂用于过二硫酸盐(PDS)活化和有机污染物在可见光照射下的降解。在这种新型的FeNi-MOFs体系中,Ni基MOFs(Ni-MOFs)由于其完全开放的孔隙、丰富的可触及活性位点以及与Fe3+/Fe2+相匹配的氧化还原电位而被选为宿主。光谱分析表明,在Ni-MOFs中,Fe分子均匀地加入并取代了部分Ni,形成了具有杂原子金属节点的FeNi-MOFs。由于相邻Ni中心的化学配位键和极化作用,在可见光照射下,FeNi-MOFs中发现了两条精确的电子传输途径,促进了Fe2+的回收,Fe3+/Fe2+循环效率大于58%。作为概念验证,所制备的FeNi-MOFs在有机污染物降解的PDS转化中具有令人满意的催化性能。此外,FeNi-MOFs的比活度高达92.6×10-4 Lmin-1m-2,是对照Ni-MOFs/Fe3+体系(7.95×10-4 Lmin-1m-2)的11.6倍,优于目前已有的催化剂。该研究加深了对Fe3+/Fe2+在Fe-掺杂体系中循环过程的认识,为设计PS-AOPs用高效Fe基催化剂提供了启发
Fig. 1. (a) XRD patterns of synthesized FeNi-MOFs, Ni-MOFs and calculated Ni-MOFs. (b) Mössbauer spectrum of FeNi-MOFs. (c) Proposed crystal structure of FeNi-MOFs. (d) SEM, (e) TEM and (f-i) EDS elemental mapping of FeNi-MOFs.Fig. 2. (a) Degradation rate of TC over different systems. (b) Effect of Fe/Ni ratio on TC degradation rate. (c) Effect of pH on TC degradation rate and total dissolved iron concentration. (d) Effect of inorganic ions on TC degradation in FeNi-MOFs/PDS system. (e) Capability of the FeNi-MOFs/PDS system for degrading various pollutants. (f) Specific activity comparisons of FeNi-MOFs and existing catalysts. Experimental conditions: [pollutant]0 = 30 mg/L; [Catalyst]0 = 0.2 g/L; [PDS]0 = 1.5 mM; [inorganic ions]0 = 5 mM.Fig. 3. (a) Quenching experiments on TC degradation. (b) DMPO-trapped EPR spectra of PDS activation over FeNi-MOFs, PDS and FeNi-MOFs/PDS under light irradiation. (c) Formation kinetics f ·OH and PDS consumption. (d) Reaction kinetics of TC, NB and BA over FeNi-MOFs/PDS system and the contribution of·OH and SO4·- toward TC degradation. Experimental conditions: [TC]0 = [NB]0 = [BA]0 = 30 mg/L; [Catalyst]0 = 0.2 g/L; [PDS]0 = 1.5 mM; [quencher]0 = 750 mM; [TPA]0 = 2 mM.Fig. 4. (a) The concentration of Fe2+ over different systems. (b) The quenching effect of TC removal rate in FeNi-MOFs/PDS system. (c,d) The XPS spectra of Fe and Ni in FeNi-MOFs with or without light irradiation. (e) The electrochemical impedance spectra. (f) Cyclic voltammetry measurements over different systems. Experimental conditions: [TC]0 = 30 mg/L; [catalyst]0 = 0.2 g/L; [PDS]0 = 1.5 mM; [Fe2+]0 = [Fe3+]0 = 4.6 mg/L.Fig. 5. (a and b) Difference charge densities of FeNi-MOFs and Ni-MOFs/Fe3+. (c) The PDOS of FeNi-MOFs. (d) The PDOS of Fe and Ni moieties in different materials. The d-band centers are marked in the PDOS curves.Fig. 6. The schematical illustration of Fe3+/Fe2+ cycle and persulfate activation for pollutant degradation over FeNi-MOFs under light irradiation.
研究意义
综上所述,本研究制备了Fe-掺杂Ni基MOFs(FeNi-MOFs),并将其引入过硫酸盐活化过程中,建立了高效的PS-AOPs。光谱分析明确了Ni-MOFs中Fe的均匀掺入,生成了具有杂原子金属节点的FeNi-MOFs。在配体-金属电荷转移和相邻Ni中心极化的作用下,形成的FeNi-MOFs可进行精确的电子传输,有利于Fe2+的回收,Fe3+/Fe2+循环效率大于58%。因此,FeNi-MOFs在PDS活化和有机污染物降解方面表现出优异的催化性能。此外,FeNi-MOFs的比活度明显高于对照Ni-MOFs/Fe3+和目前报道的先进催化剂。该研究揭示了过硫酸盐活化异相催化剂中加速Fe3+/Fe2+氧化还原循环的内在机理,为设计和合成用于PS-AOPs的高性能Fe基催化剂提供了新的思路。
Dengke Wang, Mengjuan Suo, Shiqin Lai, Lanqing Deng, Jiayi Liu, Jun Yang, Siqi Chen, Mei-Feng Wu, Jian-Ping Zou, Photoinduced acceleration of Fe3+/Fe2+ cycle in heterogeneous FeNi-MOFs to boost peroxodisulfate activation for organic pollutant degradation, Applied Catalysis B: Environmental, 2023, https://doi.org/10.1016/j.apcatb.2022.122054