电化学溶出法尺寸可控合成铜基氧还原反应催化剂:从纳米粒子到原子团簇和单原子

Electrochemical-leaching route for the size-controllable synthesis of copper-based oxygen reduction reaction catalysts:From nanoparticles to atomic clusters and single atoms

从纳米尺度到亚纳米尺度甚至到原子尺度的非贵金属粒子的尺寸可控合成对阐明金属催化剂对氧还原反应催化的尺寸效应有重要意义.本文中,我们提出了一种电化学溶出策略,用于在硫掺杂的还原氧化石墨烯上自上而下制备铜纳米粒子、原子簇及单原子.在该方法中,首先电沉积获得铜纳米粒子(约8 nm),而后使用溶出伏安法,通过调控终止电位可控地将铜纳米粒子尺寸降低至原子簇尺度(约2 nm)和单原子尺度(<1 nm).对活性铜物种尺寸的有效调控使我们可以方便地从多尺度研究铜催化氧还原反应中的尺寸效应.结果表明,单原子铜表现出良好的氧还原反应催化性能,其半波电位为0.86 V,电子转移数为3.98,并具有长期稳定性,远优于其他大尺寸铜颗粒.这些研究结果为自上而下制备特定尺寸金属离子提供了新途径,将有利于尺寸可控氧还原电催化剂的未来设计.

Size-controllable synthesis of non-noble metal particles ranging from nanometer to subnanometer and atomic level is of great significance for demonstrating the size effects of metallic catalysts towards oxygen reduction reaction(ORR)catalysis.Herein,we propose an electrochemical leaching strategy for the top-down synthesis of Cu nanoparticles(NPs),atomic clusters(ACs)and single atoms(SAs)on sulfur-doped reduced graphene oxide(Sr GO).Within this strategy,Cu NPs(about 8 nm)were electrodeposited and subsequently controllably downsized to ACs(about 2 nm)and SAs(<1 nm)via a stripping voltammetry method by adjusting the termination potential.The effective control in the size of active Cu species allowed us to conveniently investigate the size effect of Cu on ORR in multiscale.Single-atom Cu exhibited good ORR performance with a half-wave potential of 0.86 V and an electron transfer number of 3.98,as well as a long-term stability,much superior to other larger Cu particles.Our findings open a new avenue for top-down synthesis of metal particles with desirable sizes,which will effectively benefit the future design of size-controlled ORR electrocatalysts.