多酸簇为母体在碳载体上生长小尺寸碳（氮）化钨（钼）及其在低温燃料电池中的应用

Transition metal carbides (nitrides) are promising co-catalyst of Pt in fuel cell. The decrease of the size and increase of the dispersion on supports can increase their chance to contact with Pt catalyst, thus fully develop their co-catalytic effect. In this project, the small-sized W(Mo)C(N) grown on carbon carriers will be prepared by using the polyoxometalate cluster (POM) as precursor to fully develop their co-catalytic effect, and to increase the performance of Pt based on the virtue of POM, including small size close to the nanometer level and variety in the structure. The POM clusters will be anchored on carbon carriers through coupling agents, and be transformed into small-sized carbides (nitrides) under certain conditions. The composition, size and dispersion of carbides (nitrides) will be tuned by changing the amount and kind of POM clusters. The bi-metallic carbides (nitrides) will be prepared by simultaneously introducing two-kind POM clusters containing different coordination atoms. The Pt nanoparticles will be deposited on the binary carriers to form three-component contacting catalyst. The combination of TEM，XPS and XAFS etc. will be used to analyzed the micro-structure and interface interaction. The electrocatalytic performance for methanol electrooxidation and oxygen reduction reaction will be tested by using cyclic voltammetry and electrochemical impedance etc. The relationship between the structure and electrochemical performance will be analyzed on the basic of structural characterizations and electrochemical tests, to elucidate the law of the synergistic catalysis and to give some basic for designing catalysts with low amount of Pt and good performance.

过渡金属碳（氮）化物是燃料电池Pt催化剂良好的助催化材料，降低尺寸并提高在载体上分散性可增加其与Pt的接触几率，从而充分发挥其助催化效果。基于多酸簇具有纳米尺寸、簇结构多变特点，本项目拟发展以多酸簇为母体在碳载体上生长小尺寸碳（氮）化钨（钼）的方法，充分发挥其助催化效果，提高Pt的利用效率。首先利用偶联剂将多酸簇锚定在石墨烯等载体上，在特定条件下处理获得小尺寸碳（氮）化物。调节多酸量，簇类型控制碳（氮）化物组成、尺寸及分散性。并拟通过同步引入两种配原子多酸获得双金属碳（氮）化物。选择合适的方法将Pt沉积在载体上形成三元接触型催化剂。结合TEM，XPS及XAFS等方法分析材料结构及界面作用等。采用循环伏安，交流阻抗等方法研究材料对甲醇氧化及氧还原反应的电催化性能。结合结构表征、电化学测试及理论计算结果，认识Pt和碳（氮）化钨（钼）的协同催化规律，为设计低Pt、性能好的催化剂提供一些实验依据。

本项目计划拟发展以多酸簇为母体在碳载体上生长小尺寸碳（氮）化钨（钼）等过渡金属间隙化合物的方法。将其担载贵金属用于燃料分子氧化和阴极氧还原等反应，获得低贵金属以及非贵金属的电催化材料。采用循环伏安，交流阻抗等方法研究材料对甲醇氧化及氧还原反应的电催化性能。结合结构表征、电化学测试及理论计算结果，认识Pt和碳（氮）化钨（钼）的协同催化规律，为设计低Pt、性能好的催化剂提供一些实验依据。 项目实施以来，按照项目研究计划，以多酸簇为母体合成过渡金属氮化物、碳化物、磷化物等过渡金属间隙化合物及电催化应用方面开展研究工作。首先，以多酸簇为母体合成了小尺寸, 高分散的钼（钨）基氮化物。担载低量的贵金属用于燃料分子氧化和氧气还原反应，提升了贵金属的催化活性和稳定性; 并在此基础上开发了非贵金属的氧还原和氧析出催化剂。同时，根据燃料电池对于高纯氢的需求以及前沿发展最新动态，利用多酸簇为母体合成组分、结构可调的过渡氮（磷）化物用于电催化分解水制氢，获得了非贵金属、高效的水分解析氢催化剂。结合多种表征方法和理论计算等手段对材料结构和性能之间的关联进行了深入的分析。在基金支持下，发表与项目研究内容相关的SCI研究论文30篇，顺利完成了项目的预期目标。其中4篇文章进入ESI Top 1% 高被引论文；授权发明专利1项；在国内学术会议做主题报告/邀请报告5次；培养博士毕业生2名、硕士毕业生6名。目前指导在读博士研究生2名，硕士研究生6名。