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Electrocatalytic urea mineralization in aqueous alkaline medium using Ni II cyclam-modified nanoparticulate TiO 2 anodes and its relationship with the simultaneous electrogeneration of H 2 on Pt counterelectrodes
Arabian Journal of Chemistry ( IF 6 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.arabjc.2017.12.029
S. Murcio-Hernández , A.V. Rueda-Solorio , J.A. Banda-Alemán , C. González-Nava , F.J. Rodríguez , E. Bustos , F. Espejel-Ayala , A. Rodríguez , S. Sepúlveda , J. Manríquez

Abstract Ni II cyclam-modified nanoparticulate TiO 2 -coated ITO electrodes (ITO/TiO 2 //Ni II cyclam) were prepared by electropolymerization of Ni II cyclam monomers to TiO 2 -coated ITO electrodes (ITO/TiO 2 ) to improve electrocatalytic urea CO(NH 2 ) 2 oxidation in alkaline aqueous solutions. A high value adding secondary effect was the collection of electrons at Pt cathodes, to simultaneously generate H 2 from water reduction. Ni II cyclam-modified ITO electrodes (ITO//Ni II cyclam) were also prepared by electropolymerization of Ni II cyclam monomers to bare ITO electrodes (ITO) for comparison purposes. In the presence of the TiO 2 nanoparticles, the urea mineralization on Ni II cyclam coatings was doubled (23.95% – organic carbon removal at 120 min of electrolysis) compared to those without TiO 2 nanoparticles (13.02% – organic carbon removal at 120 min of electrolysis). In agreement, the faradaic efficiency for H 2 generation at the Pt cathode, electrically connected to an anode having TiO 2 nanoparticles (0.99 at 120 min of electrolysis), was also twice as effective than that observed when the same Pt cathode was electrically connected to an anode without TiO 2 nanoparticles (0.46 at 120 min of electrolysis). The experimental results indicated that the poisoning of Ni II centers (which is caused by an excessive production of CO intermediates during the urea oxidation on both Ni II cyclam-modified anodes) was strongly inhibited in the presence of the nanoparticulate TiO 2 |Ni II cyclam junction. A final comparison between our results and those reported in selected publications revealed that the Ni II cyclam-modified nanoparticulate TiO 2 -coated ITO anodes here developed, constitutes a promising electrocatalytic system for performing direct urea mineralization at a relative short electrolysis time. Furthermore, the combination of the following phenomena: (a) effective charge separation on the semiconducting ITO|nanoparticulate TiO 2 junctions, (b) remarkable capabilities of the nanoporous TiO 2 films for tuning the load of OH − anions demanded by the urea oxidation and, (c) outstanding capabilities of the TiO 2 nanoparticles for capturing CO intermediates (at Ti 3+ donor sites), successfully promoted the enhancement of the electron external transport to Pt cathodes, and consequently improved the faradaic efficiency associated to the cathodic generation of H 2 .

中文翻译:

使用Ni II cyclam修饰的纳米颗粒TiO 2 阳极在碱性水溶液中电催化尿素矿化及其与Pt对电极上同时电生成H 2 的关系

摘要 Ni II cyclam 改性纳米粒子TiO 2 包覆ITO 电极(ITO/TiO 2 //Ni II cyclam)通过Ni II cyclam 单体电聚合到TiO 2 包覆的ITO电极(ITO/TiO 2 )上以提高电催化尿素的性能。 CO(NH 2 ) 2 在碱性水溶液中氧化。一个高附加值的二次效应是在 Pt 阴极收集电子,同时通过水还原生成 H 2 。Ni II cyclam 修饰的 ITO 电极 (ITO//Ni II cyclam) 也通过将 Ni II cyclam 单体电聚合到裸 ITO 电极 (ITO) 来制备,以进行比较。在 TiO 2 纳米颗粒存在的情况下,与没有 TiO 2 纳米颗粒的那些相比,Ni II cyclam 涂层上的尿素矿化作用增加了一倍(23.95% - 电解 120 分钟时去除有机碳)(13. 02% – 电解 120 分钟时去除有机碳)。一致地,在与具有 TiO 2 纳米颗粒的阳极电连接的 Pt 阴极上产生 H 2 的法拉第效率(电解 120 分钟时为 0.99),其效率也是相同 Pt 阴极电连接到不含 TiO 2 纳米颗粒的阳极(电解 120 分钟时为 0.46)。实验结果表明,在纳米颗粒 TiO 2 |Ni II cyclam 的存在下,Ni II 中心的中毒(由在两个 Ni II cyclam 改性阳极上尿素氧化过程中过量产生 CO 中间体引起)受到强烈抑制。交界处。我们的结果与选定出版物中报道的结果之间的最终比较表明,这里开发的 Ni II cyclam 改性纳米颗粒 TiO 2 涂覆的 ITO 阳极构成了一种有前途的电催化系统,用于在相对较短的电解时间内进行直接尿素矿化。此外,以下现象的组合:(a) 半导体 ITO|纳米颗粒 TiO 2 结上的有效电荷分离,(b) 纳米多孔 TiO 2 薄膜在调节尿素氧化所需的 OH - 阴离子负载方面的显着能力和, (c) TiO 2 纳米粒子在捕获 CO 中间体(在 Ti 3+ 供体位点)方面的出色能力,成功地促进了向 Pt 阴极的电子外部传输,
更新日期:2020-01-01
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