Engineering the active phase in Ni-BDC via Cr doping and electrochemical reconstruction for efficient methanol oxidation

Abstract

NiOOH serves as the active phase of Ni-based electrocatalysts in the methanol oxidation reaction (MOR), where the formation efficacy directly determines the overall electrocatalytic performance. However, the low efficiency in the conversion of Ni²⁺ to Ni³⁺ restricts the formation of NiOOH in Ni-based electrocatalysts. We have selected CrNi-BDC as the pre-electrocatalyst, in which Cr doping modulates the reconstruction behavior of CrNi-BDC during the electrochemical process. Specifically, the synergistic effect of Cr doping and electrochemical reconstruction not only facilitates the formation of NiOOH, but also drives the transformation of nanosheets into a porous structure to expose more active sites. Meanwhile, there are more OH⁻ absorbed on the surface of R-CrNi-BDC, benefitting from the chemical reconstruction from Ni²⁺ to Ni³⁺, which lays a critical foundation for the MOR performance of CrNi-BDC. The reconstructed CrNi-BDC (R-CrNi-BDC) exhibits exceptional MOR performance (256 mA cm⁻² at 1.6 V vs. RHE) and maintains excellent stability for 30 h. This study provides a novel strategy for designing high efficiency MOR electrocatalysts by regulating the formation efficiency of the Ni-based active phase.