Atomically inner tandem catalysts for electrochemical reduction of carbon dioxide

Tandem catalysis represents an efficient strategy for the electrochemical reduction of CO2 (CO2RR) to complex products, whereas the random CO migration in this process inevitably decreases the catalytic efficiency. Herein, we theoretically proposed a new type of inner tandem catalyst with two neighboring single atom active sites, which enabled the directional migration of adsorbed intermediates between adjacent binding centers through a feasible configuration transition. Such configuration transition is driven by the affinities of C and O atoms in intermediates on the two binding centers of the inner tandem active sites. Guided by this strategy, the neighboring single-atom system of Co-N-Cr was discovered for efficient CH4 formation towards the CO2RR with a remarkably low thermodynamic energy barrier of 0.35 eV for the whole path and kinetic activation energy of 0.09 eV for intermediate migration. With the complementary and synergistic catalytic roles of Co and Cr sites, the CO2RR was facilitated via the inner tandem process. Compared with the conventional tandem system, the inner tandem catalysis is distinctly advanced in the enhancement of activity and selectivity for the desired product, which broadens the tandem catalyst family for wide catalysis. A new concept of "inner tandem catalysis" was established to boost the conversion of CO2 into highly reduced products through the directional transfer of adsorbed intermediates instead of the random transfer of CO in traditional tandem catalysis.