分子前驱体衍生的氧化镍电极催化水氧化性能研究（英文）

发布时间：2018-08-26 14:15

【摘要】：太阳能分解水制氢是解决当前能源和环境危机的潜在手段之一.其中由于水氧化半反应涉及4个电子和4个质子的转移,因此是全分解水反应的瓶颈所在.为了发展高效的水氧化催化剂,降低水氧化过电位,人们付出了巨大的努力.目前活性最高的水氧化催化剂都是基于钌和铱的贵金属催化剂,高昂的成本阻碍了这些催化剂的规模化应用,因此人们尝试利用各种方法制备基于廉价金属的水氧化催化剂.2008年,Nocera课题组利用电沉积法从磷酸溶液中得到了高活性氧化钴催化剂,之后该法逐渐得到推广.最近,Spiccia和Allen课题组利用分子前驱体通过电沉积法制备了氧化镍催化剂,但其催化活性和稳定性有待进一步提高.本文将一个简单的镍配合物[Ni(en)_3]Cl_2(en=1,2-乙二胺)作为前驱体溶解到磷酸缓冲溶液中,在FTO基底上电沉积得到具有高催化活性的氧化镍水氧化催化剂.在pH=11的磷酸缓冲溶液中,由分子前驱体沉积所得到的NiO_x的催化电流达到1 mA/cm~2时的过电位为375 mV,且可稳定工作10 h以上.其催化过程中的Tafel斜率为46 mV/decade,表现出优异的动力学特性.该电极和之前文献中催化活性最高的从分子前驱体衍生得到的NiO_x相比展现出较大的优势.比如在1.3 V(相对于NHE)电压下,[Ni(en)3]Cl2衍生的NiO_x催化电流密度可以达到8.5 mA/cm~2,法拉第效率为98%.而Ni-氨基乙酸衍生的NiO_x在相同条件下催化电流密度为4 mA/cm~2,法拉第效率仅为60%.该工作充分证明以分子配合物作为前驱体是制备高效高稳定性多相水氧化催化剂的简便途径.有机配体和金属螯合的分子前驱体在结构上具有灵活可调的特性,从而有助于构建活性和效率更高的催化体系.
[Abstract]:Solar energy decomposing water to produce hydrogen is one of the potential methods to solve the current energy and environmental crisis. Because the water oxidation half reaction involves the transfer of 4 electrons and 4 protons, it is the bottleneck of the total decomposition of water reaction. In order to develop efficient water oxidation catalyst and reduce water oxidation overpotential, great efforts have been made. The most active catalysts for water oxidation are precious metal catalysts based on ruthenium and iridium, which are hindered by their high cost. Therefore, a variety of methods were used to prepare water oxidation catalysts based on cheap metals. In 2008, Nocera team obtained highly active cobalt oxide catalysts from phosphoric acid solution by electrodeposition, and the method was gradually popularized. Recently, the Spiccia and Allen groups prepared nickel oxide catalysts by electrodeposition using molecular precursors, but their catalytic activity and stability need to be further improved. In this paper, a simple nickel complex [Ni (en) _ 3] Cl_2 (en=1,2- ethylenediamine) was dissolved in phosphoric acid buffer solution as precursor, and electrodeposited on FTO substrate to obtain a catalyst with high catalytic activity for water oxidation of nickel oxide. In the phosphoric acid buffer solution of pH=11, the catalytic current of NiO_x deposited by the molecular precursor reached 1 mA/cm~ 2 with an overpotential of 375 mV, and a stable working time of more than 10 h. The Tafel slope of 46 mV/decade, in the catalytic process showed excellent kinetic properties. Compared with the NiO_x derived from the molecular precursor, the electrode has a great advantage over the NiO_x derived from the molecular precursor, which has the highest catalytic activity in previous literatures. For example, at 1.3 V (relative to NHE), the current density of NiO_x derived from [Ni (en) 3] Cl2 can reach 8.5 mA/cm~2, Faraday efficiency of 98. However, the Faraday efficiency of NiO_x derived from Ni- aminoacetic acid was only 60 under the same catalytic current density of 4 mA/cm~2,. This work fully proves that the molecular complex as precursor is a simple way to prepare high efficiency and high stability multiphase water oxidation catalyst. Organic ligands and metal-chelated molecular precursors have flexible and adjustable structure, which is helpful to construct a more active and efficient catalytic system.
【作者单位】：大连理工大学精细化工国家重点实验室;瑞典皇家工学院化学系;
【基金】：supported by the National Basic Research Program of China(973 program,2014CB239402) the National Natural Science Foundation of China(21476043) the Swedish Energy Agency and K&A Wallenberg Foundation~~
【分类号】：O643.36;TQ116.2

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