Low‐Valence Zn^δ+ (0<δ<2) Single‐Atom Material as Highly Efficient Electrocatalyst for CO₂ Reduction

Abstract

An itrogen-stabilized single-atom catalyst containing low-valence zinc atoms (Zn d+ -NC) is reported. It contains saturated four-coordinate (Zn-N 4 )a nd unsaturated threecoordinate (Zn-N 3 )s ites.T he latter makes Zn al ow-valence state,a sdeduced from X-ray photoelectron spectroscopy, Xray absorption spectroscopy, electron paramagnetic resonance, and density functional theory.Z n d+ -NC catalyzese lectrochemical reduction of CO 2 to CO with near-unity selectivity in water at an overpotential as lowa s3 10 mV.Acurrent density up to 1Acm À2 can be achieved together with high CO selectivity of > 95 %using Zn d+ -NC in aflowcell. Calculations suggest that the unsaturated Zn-N 3 could dramatically reduce the energy barrier by stabilizing the COOH* intermediate owingtothe electron-rich environment of Zn. This work sheds light on the relationship among coordination number,valence state,a nd catalytic performance and achieves high current densities relevant for industrial applications.

Electrocatalytic CO2 reduction towards industrial applications

“…In addition to the above modification of the M-N 4 structure, another way to improve the current density of the M-N-C catalyst is to change the symmetrical M-N 4 structure formed by the N-coordinated single metal atom on the carbon base plane so that the catalyst generates unsaturated coordination; the unsaturated coordination facilitates the selective adsorption of the substrate CO 2 and the corresponding intermediates. As shown in Figure 3G, Li et al 73 prepared a nitrogen-doped carbon-supported low-valence zinc SAC (Zn δ+ -NC) by adjusting the coordination environment at the atomic level and then optimizing the electronic structure of the active center, which can efficiently reduce CO 2 to CO. The team demonstrated the excellent performance mechanism of the catalyst both theoretically and experimentally.…”