Mn-N-C氧还原催化剂活性位密度和电子结构的双重调控及作用机理研究

The development of high-performance and low-cost non-noble metal catalysts for oxygen reduction reaction (ORR) has always been an important bottleneck for the commercialization of proton exchange membrane fuel cell. ORR in acid system has been the pursuant goal for a long time. Mn-N-C catalyst is a new kind of ORR catalytic material with practical application prospects, but its performance still needs to be further improved. This project plans to regulate the active-site density and electronic structure of Mn-N-C catalyst to improve its ORR catalytic performance. The active-site density of Mn-N-C can be effectively controlled by the combining roles of 3D space restriction, hydrogen bonding and electrostatic adsorption of polymer hydrosol. The electronic effect derived from the decorated ultrathin MoS2 nanosheets can improve the electronic structure of Mn-N-C and promote its intrinsic catalytic activity. The investigation focuses on finding out the optimal condition to improve the active-site density and intrinsic catalytic activity of Mn-N-C catalyst and obtaining the non-noble metal catalysts with the optimization of ORR performance. Lastly, integrating with the quantum chemistry calculation, the mechanism of the electronic effect on the improvement of ORR performance will be revealed. The implementation of this project will provide a new method for the development of advanced non-noble metal catalysts and promote the practical application of fuel cell with great significance.

高性能、低成本的酸性体系非贵金属氧还原(ORR)催化剂的开发一直是实现质子交换膜燃料电池商业化的重要瓶颈，Mn-N-C催化剂是新近出现的一类具有实际应用前景的ORR催化材料，但其性能仍有待于进一步改善。本项目拟针对Mn-N-C催化剂的活性位密度和电子结构进行双重调控，改善催化剂的催化性能。利用高分子水溶胶的3D空间限域作用、氢键作用和静电吸附作用，有效调控Mn-N-C催化剂的活性位密度；利用超薄MoS2纳米片的修饰来改善Mn-N-C催化剂的电子结构，提高催化剂的本征催化活性；明确提高Mn-N-C催化剂的活性位密度和本征催化活性的最优工艺条件，获得ORR性能优异的Mn-N-C催化剂。结合量化计算，揭示超薄MoS2纳米片与Mn-N-C催化剂之间的电子效应对催化性能的改善机理。本项目的实施可望为开发高性能非贵金属催化剂提供一条新途径，对促进质子交换膜燃料电池的实用化具有重要意义。

针对质子交换膜燃料电池中重要反应依赖于Pt金属的催化，设计了不同的策略提高Pt催化剂性能，并开发了不同的非铂催化剂。通过金属载体相互作用的调控增强了Pt基催化剂的催化性能，设计了高性能、长寿命双活性中心氧还原催化剂。采用气相迁移法制备了Mn-N-C非铂氧还原催化剂，模板法制备了三明治结构Co嵌入的Co-N-C氧还原催化剂，采用原子层沉积技术制备了低铂催化剂，开发了具有双活性中心的 Pt/Co-N-C复合催化剂。揭示了催化剂孔结构、尺寸以及活性中心结构、分散度对催化剂氧还原性能增强的影响规律与作用机理，为设计高活性、高稳定性低成本氧还原催化剂提供理论依据。