To address the challenges of iron leaching and poor recyclability in traditional Fenton systems,a ternary heterojunction catalyst (Flaws-MoS2/Fe/g-C3N4) was constructed via Fe doping and defective MoS2 coupling on a g-C3N4 substrate.The interfacial regulation mechanism and piezoelectric-catalytic synergy were systematically investigated.Results demonstrated that Fe doping significantly increased the specific surface area of g-C3N4 (from 15 to 80.95 m2·g-1) and stabilized Fe sites through Fe-Nx bonding,effectively suppressing iron leaching.The edge S defects in MoS2 induced an acidic microenvironment,enhancing Fe3+/Fe2+ cycling and H2O2 activation.The optimized catalyst (3% Fe) achieved a RhB removal rate of 99.91% (kobs=0.244 9 min-1) within 20 min under ultrasound-assisted H2O2 conditions,outperforming pristine Fe-g-C3N4 by 5-fold.Quenching experiments confirmed ·OH as the dominant reactive species,while EPR analysis revealed synergistic contributions from ·${O}_{2}^{-}$ and ·OH.Notably,the piezoelectric-catalytic efficiency (Visible light with H2O2:99.41%) rivaled photo-Fenton performance,and the catalyst retained 87.57% activity after 5 cycles.
在光照的条件下对材料进行光激发,以在导带和价带中产生电子和空穴[式(1)],电子可以将部分三价铁转换为二价铁[式(2)],也可以和氧气反应生成超氧自由基[式(3)],而空穴可以和氢氧根反应生成小部分羟基自由基[式(4)]加入H2O2后,材料中大量的Fe2+表面发生Fenton反应生成Fe3+和·OH[式(5)]。而Mo4+也可以与Fe3+反应作用将其转化为Mo6+,同时将Fe3+还原为Fe2+[式(6)]。两组Fe3+/Fe2+循环模式的存在极大提高了Fe3+/Fe2+转化的效率。Mo6+也可以通过与过氧化氢和超氧自由基反应循环生成四价钼[式(7)、(8)]。上述高价钼的存在已通过XPS Mo 3d光谱图证明。而Mo6+在还原的过程中产生O2,又进一步强化了光生电子和O2结合产生超氧自由基的过程(3)。这也和淬灭实验结果吻合。整个体系可以快速分解H2O2,产生大量羟基自由基和超氧自由基来降解污染物,同时实现双Fe3+/Fe2+循环模式的极大钼和铁的循环效率,使光催化Fenton效率得到提升。
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