Constructing N-Coordinated Co and Cu Single-Atomic-Pair Sites toward Boosted CO2 Photoreduction

The visible-light-driven photocatalytic reduction reaction of carbon dioxide (CO 2 ) (CO 2 RR) to value-added fuels presents a feasible approach to curb anthropogenic CO 2 emissions and mitigate the increasing energy crisis. However, developing photocatalysts with excellent performance still remains a great challenge in this field. Herein Co,Cu,N-codoped carbon nanoparticles (Co 1 Cu 1 /NC) were fabricated through the pyrolysis of zeolitic imidazolate framework (ZIF-8) with Cu(NO 3 ) 2 adsorbed inside the cavities and CoTBPP decorated over the surface of ZIF. Spherical aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and electron energy loss spectroscopy measurements disclose the dual-metal single-atomic nature of Co 1 Cu 1 /NC consisting of atomically dispersed Co–Cu pair sites on a nitrogen-doped carbon support. Extended X-ray absorption fine-structure analysis reveals the tetra-N-coordinated nature of each metal in Co 1 Cu 1 /NC (N 2 –Co–N 2 –Cu–N 2 ). For the purpose of comparative study, Co,N- and Cu,N-codoped carbon nanoparticles (Co 1 /NC and Cu 1 /NC) also with single atomic site nature have been fabricated following the same route. The as-prepared Co 1 Cu 1 /NC exhibits highly effective photocatalytic CO 2 -to-CO reduction with a considerably high CO-generating yield of 22.46 mmol g –1 and a CO selectivity of 83.4% after 2 h of visible-light irradiation. Experimental characterizations and in particular theoretical calculations disclose the close association of the remarkable CO 2 RR catalytic activity of Co 1 Cu 1 /NC with the synergetic effect of the Co–Cu atomic-pair sites, which facilitate the conversion of CO 2 to CO via lowering the energy barrier for the formation of the *COOH intermediate. This work paves a new avenue for the rational design and construction of atomic-pair photocatalysts with boosted performance.