Asymmetric coordinated single-atom Pd sites for high performance CO2 electroreduction and Zn-CO2 battery

Single-atom catalysts (SACs) have attracted great attention for electrocatalysis. The coordination configurations of heteroatoms surrounding the metal center have a significant influence on the catalytic performance. The construction of asymmetric coordination configurations has recently been found to be an efficient strategy to improve electrocatalytic performance. However, noble-metal-based SACs with an asymmetric coordination environment have seldom been achieved. Herein, we rationally design and construct single-atom Pd catalysts with asymmetric Pd1O3C1 or Pd1N3C1 sites anchored on oxidized mesoporous carbon with optimized porosity and hydrophobicity. The as-prepared catalyst (Pd1-O-CB) selectively produces CO with a high CO Faradaic efficiency (FECO) of 99.6 % at a low potential of -0.6 V versus reversible hydrogen electrode (RHE). Furthermore, the Pd1-O-CB-based gas diffusion layer exhibits a high current density of 280.4 mA cm-2 and long-term stability over 48 h benefitted from the regulated porosity and hydrophobicity of the tri-interface. Finally, a rechargeable Zn-CO2 battery is constructed with the optimal gas diffusion electrode to deliver a maximal power density of 1.72 mW cm-2.

Automated summary

Single-atom Pd catalysts with asymmetric coordination environments have been developed and anchored on optimized oxidized mesoporous carbon. The catalyst exhibits high selectivity for CO production and high Faradaic efficiency. Furthermore, the catalyst-based gas diffusion layer shows excellent current density and long-term stability. A rechargeable Zn-CO2 battery is constructed with the optimal gas diffusion electrode, achieving a high power density.