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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.
Hydrogen production from solar energy is one of the potential solutions to the current energy and environmental crisis, in which the half-reaction of water involves the transfer of four electrons and four protons and is therefore the bottleneck in the reaction of fully decomposed water. Oxidation catalyst to reduce water oxidation potential, people have made great efforts.Now the most active water oxidation catalysts are based on the noble metal catalysts of ruthenium and iridium, high cost hinder the large-scale application of these catalysts, so people try to use each Method of preparation based on cheap metal-based water oxidation catalyst .2008 years, Nocera research group using electrodeposition method obtained from phosphoric acid solution of high activity cobalt oxide catalyst, the law was gradually promoted .Recently, Spiccia and Allen group using molecular precursor NiO catalyst was prepared by electrodeposition method, but its catalytic activity and stability need to be further improved.In this paper, a simple nickel complex [Ni (en) _3] Cl_2 (en = ethylenediamine) The precursor was dissolved in phosphate buffer solution and electrodeposited on the FTO substrate to obtain the nickel oxyhydroxide catalyst with high catalytic activity. Buffer solution, the NiO_x obtained by molecular precursor deposition has an overpotential of 375 mV when it reaches 1 mA / cm 2 and can work stably for more than 10 h.The Tafel slope during catalysis is 46 mV / decade, showing excellent kinetic properties.The electrode exhibits a great advantage over NiOx, the most catalytically active precursor derived from the previous literature, for example at 1.3 V (vs. NHE) The current density of NiO_x catalyzed by Ni (en) 3] Cl2 can reach 8.5 mA / cm 2 and the Faraday efficiency is 98% .The NiO_x derived from Ni-glycine can catalyze the current density of 4 mA / cm 2 under the same conditions , The Faraday efficiency is only 60% .This work fully proved that the molecular complex as a precursor is a convenient way to prepare high efficient and stable multi-phase water oxidation catalyst.Organic ligands and metal chelated molecular precursors are structurally flexible Tunable properties, which helps to build a more active and efficient catalytic system.