杂原子掺杂碳基材料氧电极双功能催化剂及其电化学性能研究
发布时间：2018-07-18 16:16
【摘要】：随着气候变暖和化石燃料供给日益衰竭迫使人类研发各种清洁能源,燃料电池、水电解、金属-空气电池等各种清洁能源转化技术成为了各国基础研究和应用研究的热点。氧电极催化剂是制约燃料电池和水电解技术商业化的主要瓶颈之一。目前,燃料电池阴极氧还原反应(ORR)用催化剂主要为贵金属Pt及其合金催化剂,电解水装置阳极氧析出反应(OER)用催化剂主要为贵金属RuO2、IrO2基催化剂。目前广泛采用的氧电极贵金属基催化剂(如铂基、钌基、铱基等)高昂的价格和有限的储量,己成为制约上述新能源转化技术实际应用的瓶颈。因此,发展高效、廉价、稳定、选择性好的氧电极催化剂将有力推动清洁能源设施的实用化。基于此,本文控制合成了一系列价格低廉,催化活性高,稳定性好的杂原子掺杂氧电极催化剂。本论文以三聚氰胺和多巴胺等富氮化合物为主要原料,以海藻酸钠为碳基材料的前驱体制备了一系列掺杂的碳基催化剂,分别深入研究了不含金属的掺杂碳基催化剂结构和性能;过渡金属钴、氮共掺杂碳基催化剂的结构和性能;金属钴和三聚氰胺及硫醇多巴胺在该系列催化剂中所起的促进作用;以及过渡金属和氮硫共掺杂时对催化剂性能与结构的影响。首先,高温热解海藻酸钠、尿素以及硫脲的复合物制备了氮硫双掺杂的碳基催化剂,记为N/S-C。探究了温度、负载量并通过XRD、SEM、XPS以及旋转圆盘电极对其性能的测试,结果表明在800℃时为最佳的碳化温度,氮硫双掺杂二者相互作用增加活性位点,OER的起始电位23 mv,与贵金属IrO2催化剂的催化活性相近,当电流密度为10mA/cm~2时,其电位值仅为1.49V,其ORR的起始电位0.86V,极限扩散电流密度为-5.83 mA/cm~2,在滴加甲醇溶液中经过9h的测试,其起始电位和电流密度衰减程度较小,则其甲醇耐受性性较稳定。其次,高温热解海藻酸钠、三聚氰胺、六水合氯化钴复合物制备含过渡金属钴氮掺杂的碳基催化剂,记为Co/N-C。分别对其温度、负载量进行了考察,并通过XRD、SEM、BET、XPS进行材料表征,实验结果表明金属钴掺杂在氮掺杂的碳基材料其催化活性较好稳定性较高,OER的起始电位190mv,当电位为1.55V时其电流密度为30.2mA/cm~2,其ORR的起始电位0.88V,极限扩散电流密度为-6.01mA/cm~2,经过7h测试之后,其电流密度仅衰减了6%左右。最后,将多巴胺溶液、硫醇和配置好的海藻酸钠溶液混合制备钴氮硫多掺杂的碳基催化剂,记为N/S/Co-C,形成了含有金属钴水凝胶,在经过冷冻干燥后形成气凝胶,再通过在氮气的氛围下高位煅烧形成碳气凝胶,NS的协同作用使其更多的活性位点暴露在外面,当加入了过度金属钴其催化活性得以提高,OER的起始电位220mv,当电流密度等于10mA/cm~2,时,其电位值为1.44V,其ORR的起始电位0.89V,极限扩散电流密度为-5.9mA/cm~2。
[Abstract]:With the increasing depletion of fossil fuel supply and climate warming, human beings are forced to develop various clean energy sources, fuel cells, water electrolysis, metal-air batteries and other clean energy conversion technologies, which have become the focus of basic research and application research in many countries. Oxygen electrode catalyst is one of the main bottlenecks restricting the commercialization of fuel cell and water electrolysis technology. At present, the catalysts for the cathodic oxygen reduction reaction (ORR) of fuel cells are mainly noble metal Pt and its alloys, and the catalysts for the anodic oxygen precipitation reaction (OER) in electrolytic water plants are mainly based on the noble metal RuO2O2IrO2. The high price and limited reserves of noble metal based catalysts (such as platinum-based, ruthenium, iridium, etc.), which are widely used at present, have become the bottleneck of the practical application of the new energy conversion technology mentioned above. Therefore, the development of efficient, cheap, stable and selective oxygen electrode catalysts will promote the utility of clean energy facilities. Based on this, a series of low cost, high catalytic activity and good stability heteroatom doped oxygen electrode catalysts were synthesized. In this paper, a series of doped carbon-based catalysts were prepared from nitrogen-rich compounds such as melamine and dopamine, and sodium alginate was used as the precursor of carbon-based materials. The structure and performance of metal-free doped carbon-based catalysts, the structure and performance of transition metal cobalt, nitrogen co-doped carbon-based catalysts, the promotive role of metallic cobalt, melamine and mercaptan dopamine in the catalysts were studied. And the effect of transition metal and nitrogen-sulfur co-doping on the performance and structure of the catalyst. Firstly, the complexes of sodium alginate, urea and thiourea were pyrolyzed at high temperature to prepare a carbon-based catalyst with double doping of nitrogen and sulfur, denoted as N / S-C. The temperature, loading amount and the properties of XRDX SEMX XPS and rotating disk electrode were investigated. The results show that the optimum carbonization temperature is 800 鈩，
本文编号：2132459
[Abstract]:With the increasing depletion of fossil fuel supply and climate warming, human beings are forced to develop various clean energy sources, fuel cells, water electrolysis, metal-air batteries and other clean energy conversion technologies, which have become the focus of basic research and application research in many countries. Oxygen electrode catalyst is one of the main bottlenecks restricting the commercialization of fuel cell and water electrolysis technology. At present, the catalysts for the cathodic oxygen reduction reaction (ORR) of fuel cells are mainly noble metal Pt and its alloys, and the catalysts for the anodic oxygen precipitation reaction (OER) in electrolytic water plants are mainly based on the noble metal RuO2O2IrO2. The high price and limited reserves of noble metal based catalysts (such as platinum-based, ruthenium, iridium, etc.), which are widely used at present, have become the bottleneck of the practical application of the new energy conversion technology mentioned above. Therefore, the development of efficient, cheap, stable and selective oxygen electrode catalysts will promote the utility of clean energy facilities. Based on this, a series of low cost, high catalytic activity and good stability heteroatom doped oxygen electrode catalysts were synthesized. In this paper, a series of doped carbon-based catalysts were prepared from nitrogen-rich compounds such as melamine and dopamine, and sodium alginate was used as the precursor of carbon-based materials. The structure and performance of metal-free doped carbon-based catalysts, the structure and performance of transition metal cobalt, nitrogen co-doped carbon-based catalysts, the promotive role of metallic cobalt, melamine and mercaptan dopamine in the catalysts were studied. And the effect of transition metal and nitrogen-sulfur co-doping on the performance and structure of the catalyst. Firstly, the complexes of sodium alginate, urea and thiourea were pyrolyzed at high temperature to prepare a carbon-based catalyst with double doping of nitrogen and sulfur, denoted as N / S-C. The temperature, loading amount and the properties of XRDX SEMX XPS and rotating disk electrode were investigated. The results show that the optimum carbonization temperature is 800 鈩，
本文编号：2132459
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