Luo Liuxuan, Fu Cehuang, Yan Xiaohui, Shen Shuiyun, Yang Fan, Guo Yangge, Zhu Fengjuan, Yang Lijun, Zhang Junliang
Institute of Fuel Cells, Key Laboratory for Power Machinery and Engineering of MOE, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Key Laboratory for Mesoscopic Chemistry of MOE, Jiangsu Provincial Lab for Nanotechnology, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
ACS Appl Mater Interfaces. 2020 Jun 10;12(23):25961-25971. doi: 10.1021/acsami.0c05605. Epub 2020 May 26.
Rationally engineering the surface physicochemical properties of nanomaterials can improve their activity and durability for various electrocatalytic and energy conversion applications. Cu-Pd/Ir (CPI) nanospheres (NSs) anchored on N-doped porous graphene (NPG) [(CPI NSs/NPG)] have been recently demonstrated as a promising electrocatalyst for the alkaline ethanol oxidation reaction (EOR); to further enhance their electrocatalytic performance, the NPG-supported CPI NSs are coated with Au submonolayer (SML) shells (SMSs), through which their surface physicochemical properties can be tuned. CPI NSs/NPG is prepared by our previously developed method and possesses the special structures of composition-graded CuPd and surface-doped Ir. The Au SMSs with designed surface coverages are formed via an electrochemical technology involving incomplete Cu underpotential deposition (UPD) and Au galvanic replacement. A distinctive volcano-type relation between the EOR electrocatalytic activity and the Au-SMS surface coverage for CPI@Au NSs/NPG is revealed, and the optimal CPI@Au NSs/NPG greatly surpasses commercial Pd/C and CPI NSs/NPG in electrocatalytic activity and noble metal utilization. More importantly, its electrocatalytic durability in 1 h chronoamperometric and 500-cycle potential cycling degradation tests is also significantly improved. According to detailed physicochemical characterizations, electrochemical analyses, and density functional theory calculations, the promoting effects of the Au SMS for enhancing the EOR electrocatalytic activity and durability of CPI NSs/NPG can be mainly attributed to the greatly weakened carbonaceous intermediate bonding and properly increased surface oxidation potential. This work also proposes a versatile and effective strategy to tune the surface physicochemical properties of metal-based nanomaterials via incomplete UPD and metal-cation galvanic replacement for advancing their electrocatalytic and energy conversion performance.
合理设计纳米材料的表面物理化学性质可以提高其在各种电催化和能量转换应用中的活性和耐久性。最近，锚定在氮掺杂多孔石墨烯（NPG）上的铜-钯/铱（CPI）纳米球（NSs）[（CPI NSs/NPG）]已被证明是一种有前途的碱性乙醇氧化反应（EOR）电催化剂；为了进一步提高其电催化性能，在NPG负载的CPI NSs上包覆金亚单层（SML）壳（SMSs），通过这种方式可以调节其表面物理化学性质。CPI NSs/NPG通过我们之前开发的方法制备，具有成分梯度的CuPd和表面掺杂Ir的特殊结构。通过涉及不完全铜欠电位沉积（UPD）和金置换反应的电化学技术形成具有设计表面覆盖率的金SMSs。揭示了CPI@Au NSs/NPG的EOR电催化活性与金-SMS表面覆盖率之间独特的火山型关系，最佳的CPI@Au NSs/NPG在电催化活性和贵金属利用率方面大大超过了商业钯/碳和CPI NSs/NPG。更重要的是，其在1小时计时电流和500次循环电位循环降解测试中的电催化耐久性也得到了显著提高。根据详细的物理化学表征、电化学分析和密度泛函理论计算，金SMS对增强CPI NSs/NPG的EOR电催化活性和耐久性的促进作用主要归因于碳质中间体键的显著减弱和表面氧化电位的适当增加。这项工作还提出了一种通用且有效的策略，通过不完全UPD和金属阳离子置换反应来调节金属基纳米材料的表面物理化学性质，以提高其电催化和能量转换性能。
