Key points are not available for this paper at this time.
Despite recent attempts using metal–organic frameworks (MOFs) directly as electrocatalysts, the electrochemical stability of MOFs and the role of in situ-formed species during electrochemistry are elusive. Using in situ spectroelectrochemistry, we present herein a comprehensive discussion on the structural and morphological evolution of MOFs (zeolitic imidazolate framework-67, ZIF-67) during both cyclic voltammetry and amperometry. Dramatic morphological changes exposing electron-accessible Co sites are evident. The intense conversion from tetrahedral Co sites in ZIF-67 to tetrahedral α-Co(OH)2 and octahedral β-Co(OH)2, and the formation of their corresponding oxidized forms (CoOOH), is observed during both the electrochemical treatments. Subsequent oxygen evolution reaction suggests the CoOOH produced from α/β-Co(OH)2 as the dominating active sites, not the metal nodes of ZIF-67. Specifically, the CoOOH from α-Co(OH)2 is most active (turnover frequency = 0.59 s–1) compared to that from β-Co(OH)2 (0.06 s–1). Our study demonstrates the importance of examining the electrochemical stability of MOFs for electrocatalyst design.
Zheng et al. (Thu,) studied this question.