Localizing bismuth single atoms around tin nanoparticles for efficient CO2 reduction and fabrication of high-performance sodium-ion batteries

Abstract

The utilization of Bi/Sn alloy-based materials has garnered significant interest as a promising avenue for the development of sodium-ion batteries and the achievement of electrocatalytic CO2 reduction. This is due to their notable attributes of high theoretical specific capacity and low working potential, as well as their abundance and high catalytic activity. Nevertheless, the practical application potential of these alloys is restrained by their inadequate electrical conductivity without incorporating conductive carbon networks to improve the electrical conductivity of the composite material and consequential volumetric fluctuations, which ultimately lead to unsatisfactory cycle life and the depletion of active components. A single-atom Bi-coated Sn nanoparticle was synthesized utilizing metal-organic framework (MOF) compounds as precursors. The resulting composite exhibits the ability to mitigate volume changes that arise during charge and discharge processes, while also enhancing the catalytic activity of the system for CO2 reduction through synergistic effects. Upon pyrolysis of the MOFs at elevated temperatures, a carbon matrix "protective layer" is formed to prevent the loss of active substances under conditions of electrode pulverization. This leads to improved cycle stability and coulomb efficiency of the battery. The ion permeation and gas diffusion are facilitated by the three-dimensional porous structures of composites. The conductive networks further improve the conductivity of materials, prevent the shedding of electrode material from electrodes, and facilitate electron transport. Consequently, the electrode demonstrates exceptional electrochemical performance, as evidenced by a high capacity of 510 mAh g−1 after 1000 cycles and a reversible capacity of 497 mAh g−1 after 500 cycles. Furthermore, the composite material demonstrates a notable degree of selectivity towards CO2 reduction, as evidenced by a coulombic efficiency of 95.7% for HCOOH at a potential of −1.1 V but only a coulombic efficiency of 2.3% for H2. Furthermore, the composite material exhibits commendable stability. The findings presented in this study offer valuable technical insights towards the attainment of carbon neutrality and carbon peaking.