A hierarchical Single-Atom Ni-N-3-C catalyst for electrochemical CO2 reduction to CO with Near-Unity faradaic efficiency in a broad potential range

Single atom catalysts have been shown highly efficient in catalyzing electrochemical CO2 reduction, but their large-scale synthesis and stable operation under high current densities are still rare. Herein a simple but robust template method was developed for gram-scale synthesis of single-atom Ni-N-C catalysts, exploiting the natural abundant and low-cost guar gum. Benefiting from its under-coordinated Ni-N-3 configuration to afford high catalytic activity and hierarchical porosity to promote mass/charge transfer, the as-fabricated Ni-N/PC catalyst achieved a low overpotential of 290 mV at 100 mA cm(-2), a near-unity faradaic efficiency in a wide potential range from -0.3 V to -0.8 V, as well as a stable operation for >70 h in a membrane electrode assembly with an extraordinary total energy efficiency of 41.0%. By mass-producing a highly potent single-atom electrocatalyst and demonstrating its stable operation in industrial-relevant conditions, this study paves the way for fulfilling the carbon neutral goal through the carbon-negative CO2RR process.