Interfacing Dense NiFe@N-Doped Carbon Nanotubes on a Ni Hollow Fiber as a High-Current-Density Gas-Penetrable Electrode for Selective CO₂ Electroreduction

Abstract

Despite proven as effective in overcoming the limitations of low CO 2 solubility and inefficient diffusion, traditional gas-diffusion electrodes used in electrocatalytic CO 2 reduction reactions (eCO 2 RR) still face challenges, such as flooding and salt precipitation, and thus exhibit insufficient efficiency and durability at high current densities. Herein, an integrated gas-penetrable electrode (GPE) is developed by interfacially growing dense N-doped carbon nanotubes, embedded with NiFe alloy nanoparticles, on the outer surface of a Ni hollow fiber (NiFe@NCNTs/Ni HF). Thanks to improved mass transfer and the abundance of well-established triphase reaction interfaces, the NiFe@NCNTs/Ni HF GPE exhibits a high CO Faradaic efficiency (FE CO ) of over 90% across a wide potential range of 240 mV. Furthermore, it displays significantly enhanced partial current density (j CO ) of up to 171.7 mA cm −2 at −1.03 V versus reversible hydrogen electrode. Notably, this GPE maintains stable FE CO and j CO values for 42 h. This work demonstrates an effective strategy for developing integrated GPEs for efficient eCO 2 RR by addressing the mass transfer limitation while achieving high efficiency and durability at high current densities.