DOI: 10.1002/adma.202300713 ISSN:

Cooperative Copper Single Atom Catalyst in Two‐dimensional Carbon Nitride for Enhanced CO2 Electrolysis to Methane

Soumyabrata Roy, Zhengyuan Li, Zhiwen Chen, Astrid Campos Mata, Pawan Kumar, Saurav Ch. Sarma, Ivo F Teixeira, Ingrid F Silva, Guanhui Gao, Nadezda V. Tarakina, Md. Golam Kibria, Chandra Veer Singh, Jingjie Wu, Pulickel M. Ajayan
  • Mechanical Engineering
  • Mechanics of Materials
  • General Materials Science


Renewable electricity powered carbon dioxide (CO2) reduction (eCO2R) to high‐value fuels like methane (CH4) holds the potential to close the carbon cycle at meaningful scales. However, this kinetically staggered 8‐electron multistep reduction still suffers from inadequate catalytic efficiency and current density. Atomic Cu‐structures can boost eCO2R‐to‐CH4 selectivity due to enhanced intermediate binding energies (BEs) resulting from favorably shifted d‐band centers. Herein, we exploit two‐dimensional carbon nitride (CN) matrices, viz. Na‐polyheptazine (PHI) and Li‐polytriazine imides (PTI), to host Cu‐N2 type single atom sites with high density (∼1.5 at%), via a facile metal ion exchange process. Optimized Cu loading in nanocrystalline Cu‐PTI maximizes eCO2R‐to‐CH4 performance with Faradaic efficiency (FECH4) of ≈68% and a high partial current density of 348 mA cm−2 at a low potential of ‐0.84 V versus RHE, surpassing the state‐of‐the‐art catalysts. Multi‐Cu substituted N‐appended nanopores in the CN frameworks yield thermodynamically stable quasi‐dual/triple sites with large interatomic distances dictated by the pore dimensions. First‐principles calculations elucidate the relative Cu‐CN cooperative effects between the two matrices and how the Cu‐Cu distance and local environment dictate the adsorbate BEs, density of states, and CO2‐to‐CH4 energy profile landscape. The 9N pores in Cu‐PTI yield cooperative Cu‐Cu sites that synergistically enhance the kinetics of the rate‐limiting steps in the eCO2R‐to‐CH4 pathway.

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