探讨了BiVO_4-BiIO_3光催化剂(BVBI)降解水体中有机污染物(甲基橙为模拟污染物)过程中,体系中的助剂三氟乙酸(TFA)的促进效果及理论机理。实验结果表明,TFA可明显提高光催化降解甲基橙的效率:反应0.5 h后加入0.25 m L TFA后降解率达到92.58%,而不加TFA降解率仅为25.50%。借助电化学分析与自由基捕获实验,我们推测TFA的助催化机理在于其有效地捕获催化剂的光生空穴(h+),促进其与光生电子(e-)的分离,提高e-利用率从而提高催化降解有机物的能力。首次利用TFA为光生空穴h+的捕获剂以提高光催化反应效率,研究成果可为光催化助剂高效降解水体中有机污染物的相关研究提供有益的借鉴。
PtCox bimetallic nanoparticles（NPs） supported on tannin-grafted collagen fiber（CF-BT） have been pre- pared via a novel synthetic strategy, and applied for catalytic hydrogenation of cinnamaldehyde（CAL）, a typic unsa- turated aldehyde. The catalysts were systematically artd specifically characterized by means of XRD, XPS, TEM-EDX and SEM to clarify the structure-property correlation. It was found that the PtCox/CF-BT catalysts exhi- bited significantly enhanced catalytic activity and desirable stability in catalytic hydrogenation of CAL, which is ascribed to the synergistic interaction between bimetallic components, the effective dispersion, the anchoring role of CF-BT matrix on bimetallic NPs, as well as the lower mass transfer resistance of the matrix.
A Pt/γ-Al2O3-C heterogeneous catalyst with improved catalytic performance was successfully prepared. Bayberry talmin（BT）, an abundant natural plant polyphenol, was utilized to modifiy the surface of the Pt/γ-Al2O3 matrix and then stabilize Pt nanoparticles（NPs）. The catalyst was systematically and specifically characterized by a collec- tion of analytic tools including XRD, XPS, FTIR, TEM, and TG. It was found that the Pt NPs were envenly dispered on the γ-Al2O3-C matrix. Meanwhile, when the catalyst was applied for selective hydrogenation of cilmamalde- hyde（CMA） in the presence of KOH promoter in solvent, excellent catalytic performance was obtained. The selecti- vity to cinnamyl alcohol（CMO） reached 97.88% with 88.45% CMA conversion within 30 min in the presence of 0.037 mol/L KOH, without significant loss of catalytic activity even under cyclic measurements for 5 times. The excelleut catalytic performances should be ascribed predominantly to the uniform and stable dispersion ofPt NPs on the γ-Al2O3-C matrix and the excellent heat stability of BT.
