Acta Chimica Sinica ›› 2023, Vol. 81 ›› Issue (11): 1478-1485.DOI: 10.6023/A23050221 Previous Articles     Next Articles

Special Issue: 庆祝《化学学报》创刊90周年合辑



刘金晶a, 杨娜b, 李莉a,*(), 魏子栋a,*()   

  1. a 重庆大学化学化工学院 重庆 401331
    b 电子科技大学材料与能源学院 成都 611731
  • 投稿日期:2023-05-10 发布日期:2023-08-28
  • 作者简介:
  • 基金资助:
    国家重点研发计划(2021YFA1501000); 国家自然科学基金(52021004)

Theoretical Study on the Regulation of Oxygen Reduction Mechanism by Modulating the Spatial Structure of Active Sites on Platinum

Jinjing Liua, Na Yangb, Li Lia(), Zidong Weia()   

  1. a School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 401331
    b School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731
  • Received:2023-05-10 Published:2023-08-28
  • Contact: *E-mail:;
  • About author:
    These authors contributed equally to this work
    Dedicated to the 90th anniversary of Acta Chimica Sinica.
  • Supported by:
    National Key Research and Development Program of China(2021YFA1501000); National Natural Science Foundation of China(52021004)

Improving the cathodic oxygen reduction reaction (ORR) activity faces significant challenges due to the linear scaling relationship and disparate adsorption strengths of the intermediate species, *OH and *OOH. This causes the ORR cannot proceed under nearly thermodynamic equilibrium potential, leading to low reaction kinetics compared to the anodic hydrogen oxidation reaction. Even with the use of optimal catalysts like Pt, the theoretical overpotential remains at around 0.45 V, because of the excessively strong *OH adsorption and weak *OOH adsorption, with *OH desorption serving as the potential determining step (PDS). In this study, we aim to enhance the intrinsic catalytic activity of ORR by constructing a three-dimensional spatial geometric structure utilizing a Pt crystalline model with multi-low index surface consisting of (100)-(110)-(111). The density functional theory calculations are employed to investigate the impact of a concave and convex arrangement formed by interlacing polycrystalline surfaces on the adsorption of *OH and *OOH. The results indicate that the investigated spatial configuration can break the linear scaling relationship between *OH and *OOH adsorption and allow for independent optimization of their adsorption strengths, thereby reducing the originally theoretical overpotential. The adsorption of intermediates reveals that the coordination unsaturation of active sites can be utilized as an indicator of the effect of the spatial geometric structure on species adsorption. The adsorption strength of the active site spatial structure follows the order of “concave”<“convex”≤“flat”, with the concave sites of Pt(111)-(100) exhibiting the most optimal adsorption strength for both *OH and *OOH. The 4e associative mechanism on single sites further reveals that the concave active sites located at Pt(111)-(100) play a significant role in independently regulating the adsorption of intermediate species and show higher catalytic activity than Pt model with single-low index surface. This is due to the minimal coordination unsaturation, which allows for a balance of *OOH and *OH adsorption strengths and then regulates the protonation of *O as the PDS. On the other hand, the 4e dissociative mechanism demonstrates that dual active sites can further enhance intrinsic catalytic activity compared to single active sites. Specifically, the “flat-concave” dual active sites at Pt(111)-(100) are shown to significantly reduce the theoretical overpotential to 0.27 V. This polycrystalline faceted catalyst with a concave-convex spatial structure is highly promising for use in other reactions that require the selective modulation of multispecies adsorption and the enhancement of intrinsic catalytic activity, particularly those that exhibit a linear scaling relationship.

Key words: Pt-based catalysts, oxygen reduction reaction, active site on polycrystalline surface, spatial structure, density functional theory