A hierarchical Single-Atom Ni-N3-C catalyst for electrochemical CO2 reduction to CO with Near-Unity faradaic efficiency in a broad potential range

Single-atom Ni-N 3 -C catalyst is mass-produced through a facile template method exploiting the natural guar gum, affording a near-unity CO selectivity in a wide potential range. Prolonged stable CO production is demonstrated with a membrane electrode assembly with an extraordinary energy efficiency of 41.0%. • Single-atom Ni-N 3 -C catalyst (Ni-N/PC) is mass-produced by using natural guar gum; • Ni-N 3 -C stabilizes *COOH through stronger Ni-C bond and affords low overpotential. • Prolonged stable CO production is demonstrated in a membrane electrode assembly. Single atom catalysts have been shown highly efficient in catalyzing electrochemical CO 2 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 CO 2 RR process.