Electrocatalytic behavior toward nitrite of a hybrid film of fosfomolybdate and organomodified silica

ABSTRACT Nanostructured organic-inorganic hybrid materials are produced for the purpose of developing and / or enhancing a property of interest. One way of obtaining hybrid materials is by immobilizing an inorganic component in an organically modified silica (ormosil) network. In this study, a Keggin type polyoxometalate, phosphomolybdic acid (HPMo), was entrapped into a silica network modified with 3- (Trimethoxysilyl) propyl methacrylate (TMPM) and a thin film of this hybrid material was deposited on a gold electrode by the dip coating method. The electrochemical reactivity of this film was explored toward nitrite ion, where the catalytic electroreduction occurred at 0.0 V vs. Ag / AgCl. The linear concentration range obtained using cyclic voltammetry was 0.20 - 1.0 mmol L-1 in acidic medium pH 1.0. 31P Nuclear Magnetic Resonance spectroscopy showed that HPMo remains intact in the ormosil network. In addition, HPMo is interacting with methacrylate groups through hydrogen bonds as shown by infrared absorption spectroscopy. The hybrid film developed here could be used for the improvement of systems able of detecting nitrite.

摘要：本研究制备纳米结构有机-无机杂化材料，旨在开发或优化目标性能。制备杂化材料的途径之一，是将无机组分固定于有机改性二氧化硅（ormosil）网络中。本研究将Keggin型多金属氧酸盐——磷钼酸（HPMo）——封装于经3-（三甲氧基硅基）丙基甲基丙烯酸酯（TMPM）改性的二氧化硅网络中，并通过浸涂法将该杂化材料的薄膜沉积于金电极表面。针对该薄膜对亚硝酸根离子的电化学反应活性展开探究，结果显示其在相对于Ag/AgCl参比电极的0.0 V电位处发生催化电还原反应。采用循环伏安法测得，在pH 1.0的酸性介质中，该检测方法的线性浓度范围为0.20~1.0 mmol·L⁻¹。31P核磁共振波谱分析结果表明，HPMo在ormosil网络中保持结构完整。此外，红外吸收光谱表征结果证实，HPMo可通过氢键与甲基丙烯酸酯基团发生相互作用。本研究制备的杂化薄膜可用于优化亚硝酸根离子检测体系。