Atomically Dispersed Ni/Cu Dual Sites for Boosting the CO₂ Reduction Reaction

Abstract

Developing diatomic catalysts (DACs) for the CO2 reduction reaction (CO2RR) has emerged as a promising leading-edge research area owing to their maximum atomic utility and more sophisticated functionalities. However, the proper design of DACs at an atomic level and an understanding of the synergistic mechanism of binary sites remain challenging. Herein, an N-rich carbon matrix with precisely controlled Ni/Cu dual sites is synthesized through the assistance of metal–organic frameworks. The as-prepared catalyst presents high CO Faradaic efficiency of over 95% from −0.39 to −1.09 V vs reversible hydrogen electrode (RHE) with the maximum value of 99.2% at −0.79 V vs RHE and long-term durability of 60 h electrolysis. Density functional theory studies reveal that the electronic redistribution and band gap narrowing induced by the adjacent NiN4 and CuN4 moieties enhance the electron conductivity and strengthen the bonding interactions between *COOH intermediates and Ni centers, thus lowering the overall reaction barriers and promoting CO generation.

The Surface State: A Tricky Part of Dual-Atom Electrocatalysts

“…Stability analysis should always be the priority before the subsequent activity analysis. 22 In this work, we selected a Fe-Ni-N6-C model (Figure 2a), a proven stable dual-atom structure, 23,24,28 as an example for illustration. We controlled the metal atom coordination environment by tuning the number of nitrogen atoms and location, affording a total of 64 DAC models.…”

“…Only a small number of DACs can retain the pristine state at the CO2RR potential, suggesting that a great majority of these 64 DACs may not be suitable for CO2RR. Surprisingly, Fe-Ni-N1,2,3,4,5,6-C, the mostly reported CO2RR catalyst, 24,28 would have its active sites occupied by 2H*. This phenomenon has been widely dismissed in previous studies (Figure 1).…”

“…surface states of DACs are potential-and pH-dependent, suggesting that a DAC could exhibit a distinctive surface state at different electrocatalytic reaction conditions. We performed the surface state analysis on the two-representative models discussed above at the characteristic potentials for various reactions, i.e., 1.60 V for oxygen evolution reaction (OER), 25 0.78 V for ORR, 26 0 V for HER, 27 −0.35 V for CO2RR, 28 and −0.4 V for nitrogen reduction reaction (NRR). 29 Because O* and HO* are also the key reaction intermediates of OER, we do not discuss the OER activities of DACs since whether the poisoning O* and HO* will participate in OER is still an open question.…”

Low‐dimensional material supported single‐atom catalysts for electrochemical CO2 reduction

“…In addition to homonuclear DMS catalysts mentioned above, the fabrication of heteronuclear DMS catalysts is also conductive to enhance the ECR performance. Up to now, heteronuclear DMS Ni/Co, 151 Zn/Co, 152 Ni/Zn, 153 Ni/Cu, 154 NiSn, 155 Ni/Fe, 148,156,157 Fe/Cu, 158 and Zn/Ln 159 catalysts have been demonstrated to be effective ECR. For example, Zhao et al 148 synthesized a catalyst with Ni–Fe DMS anchored on NC for ECR.…”

Atomic‐ and Molecular‐Level Modulation of Dispersed Active Sites for Electrocatalytic CO2Reduction

“…Besides, the synergistic effect of dual‐atomic sites is considered to induce the electronic effect of contiguous metal atoms [48a,50] . For instance, He and coworkers synthesised the Ni−Cu dual sites embedded in N‐doped carbon matrices, of which N 4 Ni/CuN 4 is their active sites for CO 2 RR [50a] …”