Steering CO Selectivity in CO<sub>2</sub> Electroreduction over Silver Microtubular Gas-Diffusion Electrodes via Surface Reconstruction
Yizhu Kuang, Guoliang Chen, Hesamoddin Rabiee, Beibei Ma, Fatereh Dorosti, Ashok Kumar Nanjundan, Zhonghua Zhu, Hao Wang, Lei Ge
Abstract
An efficient gas diffusion electrode (GDE) is crucial for enhancing mass transport involving gas-phase CO 2 conversion in the electrochemical CO 2 reduction reaction (CO 2 RR). Microtubular hollow fiber GDE (HFGDE) with a porous hierarchical wall has garnered significant attention, which can modulate the triple-phase reaction zone and improve the performance of CO 2 RR. Simultaneously, engineering nano/microstructure surfaces of electrocatalysts have been demonstrated to effectively enhance the selectivity and activity in CO 2 RR. Here, we developed a porous microparticle Ag-based HFGDE via an in situ electrochemical oxidation–reduction method. Both the activity and selectivity of CO 2 to CO conversion in the porous microparticle Ag-based HFGDE showed significant enhancement over the pristine and thermal reduced Ag HFGDE without surface reconstruction. At −1.2 V vs RHE, the faradaic efficiency for CO is 94%, with a partial current density of 83.4 mA cm –2, surpassing that of thermal treatment electrodes, which is only 26% with a partial current density of 12.3 mA cm –2 . The distinctive reconstruction nano/microstructure on the electrocatalyst surface could be attributed to decreasing the activation energy barrier in the rate-limiting step of initial electron/proton transfer. This work represents a facile strategy for surface reconstruction of electrocatalysts in HFGDE as advanced electrode materials to enhance the efficiency of the CO 2 conversion.