金属纳米催化剂的电化学液相连续控制合成方法与原理研究

The performance promotion and cost reduction of platinum-based metal nanocatalysts are important measures to promote the commercialization of green energy conversion devices. Electrochemically-controlled synthesis has a significant advantage in green synthesis of metal nanocatalysts with high activity and high surface energy. However, the output of current synthesis methods is limited by the growth of metal nanoparticles on the two-dimensional electrode surface and can not satisfy industrial requirements. In the previous work, an electrochemical reactor was developed independently, and the electrochemically-controlled synthesis of metal nanocatalysts in three-dimensional liquid phase was realized. The work has obtained the national invention patent authorization by China, USA and Japan hence it lays a technical foundation for the scale preparation of Pt-group metal nanocatalysts with high surface energy. This project will further develop the method of continuous electrochemically-controlled synthesis of metal nanocatalyst in liquid phase to realize the large-scale preparation of supported metal nanocatalysts with small particle size and high efficiency. The performance，catalytic reaction mechanism and structure-activity relationship of the obtained metal nanocatalysts will be characterized by utilizing fuel cell test, in situ infrared spectroscopy, Cs-corrected TEM and other advanced techniques, so as to provide ideas for the design of practical nanocatalysts. The principle of the electrochemically-controlled synthesis of metal nanocatalyst in liquid phase will be explored by combining the simulation experiments of microelectrodes with the in-situ observation of the growth process by in-situ TEM, then it is excepted to build a theoretical foundation for the applicability of this method in other fields.

铂族金属为主的金属纳米催化剂的性能提升和成本降低，是推动绿色能源转换装置商业化应用的重要措施。电化学控制合成方法在绿色合成高活性的高表面能铂族金属纳米催化剂方面具有显著的优势，但现有方法的产量受限于纳米粒子在电极二维表面的成核生长方式，尚不能满足工业化应用的需求。申请人前期自主研制的电化学反应器，可实现金属纳米催化剂在三维空间的电化学液相控制合成，已获得中、美、日等国家发明专利授权，为高表面能铂族金属纳米催化剂的规模制备奠定了技术基础。本项目将进一步发展金属纳米催化剂的电化学液相连续控制合成方法，实现小粒径负载型高效金属纳米催化剂的规模制备；运用燃料电池测试、原位红外光谱、球差透射电镜等技术评价所制得的金属纳米催化剂性能，研究催化反应机理和构效关系；结合微电极模拟实验、原位透射电镜技术和理论计算方法，探究三维空间中的电化学液相控制合成原理，为拓展该方法的适用性奠定理论基础。

铂族金属为主的金属纳米催化剂的性能提升和成本降低，是推动绿色能源转换装置商业化应用的重要措施。电化学控制合成方法在绿色合成高活性的高表面能铂族金属纳米催化剂方面具有显著的优势，但原有方法的产量受限于纳米粒子在电极二维表面的成核生长方式，尚不能满足工业化应用的需求。针对上述问题，本项目通过自主研发，建立了基于电化学流动反应器系统的电化学液相控制合成方法，实现了金属纳米催化剂在三维空间的电化学液相控制合成，为高表面能铂族金属纳米催化剂的实际应用奠定了技术基础。利用MEMS技术和微探针技术对电化学液相控制合成原理进行探究，发现处于电场作用下的导电粒子周围存在局域增强电势，是驱动金属纳米粒子在碳载体表面直接沉积的驱动力，并据此提出了液相中局域增强电势可控合成制备碳载高密度表面台阶原子金属纳米催化剂（HDSA-M/C）的新原理。电化学液相连续控制合成方法首先应用于高指数晶面碳载铂纳米催化剂的连续控制合成，采用原位红外光谱、球差透射电镜、电化学表征等技术评价所制得的催化剂表面结构与催化性能，发现与相同粒径和载量的商业碳载铂催化剂相比，该项目制得的催化剂的催化活性和稳定性具有显著提升。为拓展电化学液相连续控制合成方法的应用范围，我们还探索了金属修饰或掺杂对催化剂性能的改变，所获得的研究结果用于指导电化学液相连续控制合成方法在其他二元金属纳米催化剂制备的应用。目前，该方法的应用拓展已实现碳纳米管负载的铂纳米催化剂以及铂钯合金纳米催化剂的连续制备，均可获得性能优异的催化剂。本项目的实施为实现高表面能金属纳米催化剂的实际应用打下了技术基础。