Synergy of dual single Ni and Co atoms on borate modified g-C3N4 for photocatalytic CO2 reduction

Dual modulation of electron and catalytic reduction as well as hole and catalytic oxidation targeting g-C3N4 is critical for efficient photocatalytic CO2 reduction. Herein, we decorated dual single Ni2+ and Co2+ atoms on borate modified ultrathin porous g-C3N4 nanosheets (NiCo-B-PCN) by a facile ion exchange method. Optimal NiCo-BO-PCN photocatalyst by regulating bimetallic molar ratio realized 43-fold CO2 photoconversion compared to pristine CN under full light irradiation. The single-atom dispersion of Ni2+ and Co2+ sites was evidenced by the high angle angular dark field-scanning transmission electron microscopy. As revealed by the characterizations such as transient absorption spectra and electrochemical curves, the photoactivity enhancement was attributed to the synergetic effects that single Ni2+ atoms could capture electrons and benefit the CO2 reduction while single Co2+ atoms could extract holes and catalyze the water oxidation. This work has provided a novel dual-modulation strategy by constructing dual single-atom photocatalysts for efficient solar fuel production.