Three-dimensional N-doped carbon nanosheets loaded with heterostructured Ni/Ni3ZnC0.7 nanoparticles for selective and efficient CO2 reduction

Abstract

Electrocatalytic CO₂ reduction (CO₂RR) has emerged as a promising approach for converting CO₂ into valuable chemicals and fuels to achieve a sustainable carbon cycle. However, the development of efficient electrocatalysts with high current densities and superior product selectivity remains a significant challenge. In this study, we present the synthesis of a porous nitrogen-doped carbon nanosheet loaded with heterostructured Ni/Ni₃ZnC_0.7 nanoparticles through a facile hydrothermal-calcination method (Ni/Ni₃ZnC_0.7-NC). Remarkably, the Ni/Ni₃ZnC_0.7-NC catalyst exhibits outstanding performance towards CO₂RR in an H-cell, demonstrating a high CO faradaic efficiency of 92.47% and a current density (j_CO) of 15.77 mA cm⁻² at 0.87 V vs. RHE. To further explore its potential industrial applications, we constructed a flow cell and a rechargeable Zn–CO₂ flow cell utilizing the Ni/Ni₃ZnC_0.7-NC catalyst as the cathode. Impressively, not only does the Ni/Ni₃ZnC_0.7-NC catalyst achieve an industrial high current density of 254 mA cm⁻² at a voltage of −1.19 V vs. RHE in the flow cell, but it also exhibits a maximum power density of 4.2 mW cm⁻² at 22 mA cm⁻² in the Zn–CO₂ flow cell, while maintaining excellent rechargeability. Density functional theory (DFT) calculations indicate that Ni/Ni₃ZnC_0.7-NC possesses more spontaneous reaction pathways for CO₂ reduction to CO, owing to its heterogeneous structure in contrast to Ni₃ZnC_0.7-NC and Ni–NC. Consequently, Ni/Ni₃ZnC_0.7-NC demonstrates accelerated CO₂RR reaction kinetics, resulting in improved catalytic activity and selectivity for CO₂RR.