Controllable Colloidal Synthesis Of Metal-based Nanomaterials For Electrocatalytic Applications

Along with the increasing issues of environmental pollution and energy consumption,the exploration and development of green energy and high-efficiency energy conversion equipment have been considered as one of the critical areas in the development of scientific and technological development.Fuel cells serve as an energy conversion device that could directly convert chemical energy into electrical energy,in which small molecular fuel and oxygen as raw materials to generate electric energy,water and a small amount of carbon dioxide.Thanks to these advantages,fuel cells are considered to be an important breakthrough for improving the energy structure and looking for new clean energy.Fuel cells using small molecules substances(including hydrogen,alcohols,etc.)as fuels,and their oxidation degree and efficiency are important indicators for judging the performance of fuel cells.Imortantly,electrocatalysts play a key role in the oxidation of small molecules.Since 1990s,nano-electrocatalysts have received widespread attentions with the rapid development of nanotechnology.In order to improve the activity and stability of the catalyst and reduce their cost,recent studies have proved that electronic structure,geometric structure and crystal boundary can be tuned by alloying,modification and control of crystal facets.Oxygen evolution reaction(OER)and ethanol oxidation reaction(EOR)are two important reactions that play an important role in the development of fuel cells.The smooth progresses of these two reactions require high-performance electrocatalysts based on the concept of design and synthesis.Recently,it is great challenge to develop the electrocatalysts for the large overpotential in OER and poor stability in EOR.As a result,starting from the design and synthesis of metal nanomaterials,this work has developed a series of high-performance electrocatalysts in OER and EOR.The details are as follows:1.Co(OH)2/Fe-BDC(BDC,terephthalic acid)composite electrocatalyst were prepared by a two-step method.Firstly,Co(OH)2 nanosheets were prepared by precipitation method.Secondly,Co(OH)2 nanosheets were modified with Fe-BDC to prepare Co(OH)2/Fe-BDC composites.In the linear scanning voltammetry(LSV)tests,the overpotential of Co(OH)2/Fe-BDC composites was reduced to 279 mV in OER.In addition,it can be seen that the as-prepared Co(OH)2/Fe-BDC composites showed excellent performance in OER,which was due to the increase of active sites by increasing the proportion of high-valent Co cations and oxygen vacancies.2.Using polyvinylpyrrolidone(PVP)as surfactant,one-dimensional PdPb3 nanochains were successfully prepared by polyol method.The PdPb3 nanochains showed high activity(2523 mA mgPd-1)and excellent stability in EOR.Due to the introduction of Pb,the Pd electronic structure in the PdPb3 nanochains was modified,and the formation of Pb oxide can provide OHad,making the catalyst performed better stability in EOR.3.PdBi-Bi(OH)3 nanochains were prepared by two-step method.Firstly,using PVP as surfactant,PdBi nanochains were prepared by polyol method.Secondly,the PdBi nanochains were modified with Bi(OH)3 in alkaline solution.Compared with commercial Pd/C,PdBi-Bi(OH)3 nanochains showed higher activity(5275 mA mgPd-1)and more excellent stability in EOR.In addition,it was revealed that the reason why PdBi-Bi(OH)3 nanochains showed excellent stability in EOR was the generation of OHad by the promotion of the modified Bi(OH)3.In summary,we have designed and prepared a series of composites with well-fined morphologies and structures based on the issues in OER and EOR,which play an important role in promoting the development of electrocatalysts in OER and EOR.