基于掺杂石墨烯/纳米金刚石核壳复合粒子的低铂与非铂催化剂的制备及其电催化性能

Core-shell structural doped graphene/nanodiamond (G/ND) composite with a ND core covered with B or N doped graphene layer is prepared by vacuum annealing ND or plasma treating ND in the B or N-contained atmosphere. The doped G/ND is expected to be a novel electrocatalyst support with an excellent conductivity originated from the graphene layer, high thermal and chemical stabilities attributed to the ND core, and a high catalytic activity for oxygen reduction reaction due to the B, N doping. The problem of the facile stack aggregate can be avoided and the controllable mesoporous channels would form when the doped G/ND is used as an electrode material instead of pure planar graphene. An isothermal hydrolyzing below boiling temperature is carried to deposit nano oxides on the doped G/ND aiming to prepare a platinum-free catalyst with a high catalytic activity and a high stability for oxygen reduction reaction. A low platinum electrocatalyst is designed using the doped G/ND as a support. An anchoring effect of the B or N doping and the defects in the graphene layer on Pt nanoparticles results in an improved stability and dispersity of Pt catalyst, as well as a reduced Pt loading. The research focuses on ND surface graphene transformation and B, N doping mechanism. The aim is to achieve controllable preparation of doped G/ND composite with desired structure and properties. An exploration on the synergetic catalytsis mechanism of Pt and B, N-doped graphene layer is an important research part in this project. The design and preparation of a Pt electrocatalyst with low cost, high catalytic activity, and high stability will promote the applications of the fuel cells in wide fields.

本项目在含有B、N原子的气氛中真空热处理或放电等离子体处理纳米金刚石（ND），制备表面B、N掺杂石墨烯（G）壳层包覆ND的掺杂G/ND核壳纳米复合粒子。以掺杂G/ND作为新型电催化剂载体材料，G壳层赋予其良好的导电性，ND芯部具有高热稳定性及化学稳定性，可避免传统石墨烯叠聚问题，构造可控的介孔通道，B、N掺杂可提高对氧还原反应的催化活性。采用非沸腾恒温水解在掺杂G/ND表面沉积纳米氧化物，制备高催化活性的氧还原非铂催化剂。掺杂G/ND作为Pt催化剂载体，通过掺杂及缺陷位对Pt粒子的锚定作用，提高Pt粒子的稳定性及分散性，减少Pt的装载量，获得高效稳定的低铂催化剂。本项目重点研究ND表面石墨烯转化及B、N掺杂机制，获得结构和性能可控的掺杂G/ND复合纳米粒子；探索掺杂G壳层与纳米氧化物或Pt金属的协同催化作用，设计制备低成本、高活性、高稳定的非铂或低铂电催化剂，促进燃料电池的广泛应用

本项目针对目前燃料电池中常用的铂基金属催化剂高成本、低寿命的问题，提出了基于高稳定纳米金刚石（Nanodiamond-ND）的非铂及低铂催化剂的制备研究。研究内容包括：以ND为高稳定的基体材料，经过高温热处理，使其表面形成B、N掺杂的石墨烯（G）壳层，芯部保留金刚石结构，获得具有壳核结构的掺杂G/ND纳米粒子。B、N掺杂的G壳层具有优异的氧还原反应（ORR）催化性能，是优良的非铂催化剂，同时ND芯部具有高热稳定性及化学稳定性，可提高催化剂的使用寿命。在ND表面沉积过渡金属氧化物或氢氧化物，通过与氮源一起热处理，可以获得Fe-N-或Co-N-G/ND，进一步提高氧还原催化活性，同时对析氧反应也具有催化作用，是一种非贵金属双功能催化剂。以ND、G/ND、氧化物/G/ND等作为高稳定的Pt催化剂载体，通过表面G层或氧化物粒子对Pt粒子的锚定作用，提高Pt粒子的稳定性及分散性，减少Pt的装载量，同时利用ND表面氧化物等与Pt协同催化效应，获得高效稳定的低铂催化剂。本项目重点研究了ND表面石墨化转变及B、N掺杂机制，获得不同类型的掺杂G/ND复合纳米粒子；探索掺杂G壳层与纳米氧化物或Pt金属的协同催化作用，设计制备了低成本、高活性、高稳定的非铂或低铂电催化剂，促进燃料电池的广泛应用。