Ni-Co-Mo/石墨烯多功能纳米催化剂的可控构筑及其碱性介质尿素电催化氧化特性

The urea electrooxidation in alkaline medium shows promising applications in the wide fields of remediation of urea-rich wastewater, hydrogen energy and fuel cells, etc. Aiming at the key scientific issue that the electrocatalysts of urea electrooxidation can not exhibit high electrocatalytic activity, low overpotential and anti-poisoning multifunctional properties, combining the properties of high catalytic activity of Ni, low overpotential of Co, anti-poisoning of Mo and high active sites of graphene, and employing the complex-redox coprecipitation method to fabricate the Ni-Co-Mo/graphene (NCM/G) multifunctional nanocatalysts by one step. To study the influences of key process parameters on the morphology and structures of NCM/G catalysts; To resolve the properties of microphysical structures and surface chemical structures of NCM/G catalysts; To investigate the electrocatalytic performances of NCM/G catalysts towards urea oxidation reaction in alkaline medium; To reveal the intrinsic relationships between the electrocatalytic activity and structural/electronic effects of NCM/G catalysts. To obtain the NCM/G catalysts which possess both the high electrocatalytic activity, low overpotential and anti-poisoning multifunctional properties and the intellectual property rights and development potential. To get the advanced preparation method of NCM/G catalysts with controllable morphology and structure. To illuminate the electrocatalytic behavior and the intrinsic action rule of electrocatalytic activity. To promote the research development of urea electrooxidation based on alkaline medium.

碱性介质尿素电催化氧化在尿素废水处理、氢能及燃料电池等领域有着广泛的应用前景。针对尿素电氧化催化剂不能展现高活性、低过电位及抗毒化多功能特性的关键科学问题，联合Ni的高催化活性、Co的低过电位、Mo的抗毒化及石墨烯的高活性面积特点，采用络合-氧化还原共沉淀法一步可控制备Ni-Co-Mo/石墨烯（NCM/G）多功能纳米催化剂。研究关键制备参数对NCM/G催化剂形貌和结构的影响；解析NCM/G催化剂的微观物理结构和表面化学结构特点；探索NCM/G催化剂在碱性介质中的尿素电催化氧化性能；揭示电催化活性与NCM/G催化剂结构效应和电子效应的内在联系。得到具有知识产权和发展潜力的高活性、低过电位和抗毒化多功能特点的NCM/G催化剂；获取结构形貌可控的NCM/G催化剂的先进制备方法；阐明NCM/G催化剂的电催化特性及其电催化活性内在作用规律。推进碱性介质尿素电催化氧化研究发展。

碱性介质尿素电催化氧化在尿素废水处理、氢能及燃料电池等领域有着广泛的应用前景。本课题针对尿素电氧化催化剂低活性、高过电位及易毒化的关键科学问题，联合Ni的高催化活性、Co的低过电位、Mo的抗毒化及石墨烯的高活性面积特点，采用络合-还原法成功制备了Ni-Co-Mo/石墨烯（NCM/G）多功能纳米催化剂，研究了Ni/Co/Mo比对催化剂形貌、结构及其电催化性能的影响；解析了催化剂的构效关系及其动力学。. 研究发现，Ni/Co/Mo比为8/1/1时，催化剂综合性能最优。其起始氧化电位、最大氧化电流密度, 催化稳定性及塔菲尔斜率分别为0.30 V vs Ag/AgCl, 51 mA cm-2/0.52 V, 58% retention/1000 s/0.5 V, 70 mV dec-1, 1mV s-1)；XRD证实NCM/G(811)催化剂中Ni, Co，Mo主要以合金和氧化态的形式存在。TEM发现NCM/G(811)催化剂的粒径为50-150 nm，优于NCM/G(90505)催化剂的100-200 nm，主要由于Co, Mo的掺入引起的结构效应，这有利于催化活性的提高。BET表明NCM/G(811)比表面积和孔径分布（46.22 m2 g-1, 3.89 nm）介于NCM/G(90505)催化剂(13.64 m2 g-1, 3.91 nm)与NCM/G(71515)催化剂（48.83 m2 g-1, 3.82 nm）之间，这说明合适的Ni/Co/Mo比有利于电活性位的提高。XPS证实NCM/G(811)催化剂的Ni2p, Co2p, Mo3d结合能发生正移，表明更多的NiOOH电活性位、Co2+物种及Mo6+含氧基团，从而提升催化剂的活性、降低过电位，提高稳定性能。. 该NCM/G(811)多功能催化剂在尿素电氧化领域具有良好的应用前景，本项目的实施也有力地推进了碱性介质尿素电氧化领域的发展。