Reordering d Orbital Energies of Single‐Site Catalysts for CO₂ Electroreduction

Abstract

The single-site catalyst (SSC) characteristic of atomically dispersed active centers will not only maximize the catalytic activity,but also provideapromising platform for establishing the structure-activity relationship.H owever,a rbitrary arrangements of active sites in the existed SSCs make it difficult for mechanism understanding and performance optimization. Now, aw ell-defined ultrathin SSC is fabricated by assembly of metal-porphyrin molecules,w hiche nables the precise identification of the active sites for d-orbital energy engineering.The activity of as-assembled products for electrocatalytic CO 2 reduction is significantly promoted via lifting up the energy level of metal d z 2 orbitals,e xhibiting ar emarkable Faradaic efficiency of 96 %a tt he overpotential of 500 mV. Furthermore,aturnover frequency of 4.21 s À1 is achieved with negligible decayo ver4 8h.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Figure 5. DFT calculation of electrocatalytic CO 2 reduction on STPyP-Co.A)Calculated free-energys tates of CO 2 reduction to CO on STPyP-Co and MTPyP-Co. B) Optimized geometry of intermediate [STPyP-Co-COOH].C ),D) Spatial representationo fHOMO orbital of [STPyP-Co-COOH] and [MTPyP-Co-COOH] intermediates, respectively.

Unpaired 3d Electrons on Atomically Dispersed Cobalt Centres in Coordination Polymers Regulate both Oxygen Reduction Reaction (ORR) Activity and Selectivity for Use in Zinc–Air Batteries

“…In this coordination field, the d xy has lower energy than , in which the occupied single electron leads to a weaker shielding of the nuclei field to destabilize the otherwise perfect square‐planar configuration (see the schematic diagram in Figure a). Similar energy level shift between d xy and with local coordination change were also seen in previous studies . We further note that the 2D square‐planar configuration is a premise to induce the vertical π–π stacking between neighbouring layers, ultimately leading to decreased system energy .…”

Heterogeneous Single‐Atom Catalysts for Electrochemical CO2 Reduction Reaction

“…[ 37 ] Since then, metal–organic complexes with well‐defined M‐N 4 sites have been extensively studied as either homogeneous catalysts or heterogeneous catalysts by immobilizing these molecular catalysts on solid supports through physical adsorption, chemical bonding, polymerization, or integration in frameworks. [ 26,38–46 ] Recently, the use of solid‐state heterogeneous SACs containing similar M‐N x moieties for CO 2 RR attracts extensive attention because of their facile and flexible preparation methods, unique electronic and geometric structure, outstanding conductivity (especially when supported on carbon materials), great structural stability, and outstanding CO 2 RR performance and durability. [ 31 ] Even though only 5 years have passed since the first adoption of metal‐doped nitrogenated carbon as CO 2 RR catalysts by Strasser group, [ 47 ] the field has developed exceptionally rapidly enabling various single metal sites and different reduction products to be developed and studied ( Figure ).…”

Optimizing Electron Densities of Ni‐N‐C Complexes by Hybrid Coordination for Efficient Electrocatalytic CO2 Reduction

“…Moreover, the hydrogen evolution reaction (HER) occurs at a very similar potential range to CO 2 RR, which leads to a low selectivity of CO 2 RR. To overcome the drawbacks mentioned above, a series of electrocatalysts including nanostructured metals, alloys, oxides, and chalcogenides have been explored to catalyze the conversion of CO 2 to CO, HCOOH, CH 3 OH, and others . Among them, carbon‐based functional materials have unique advantages for electrocatalysis owing to their tunable molecular structures, high electrical conductivity, and strong acidic/alkaline resistance .…”

“…To overcome the drawbacksm entioned above,aseries of electrocatalysts including nanostructured metals, alloys, oxides, and chalcogenides have been explored to catalyze the conversion of CO 2 to CO, HCOOH, CH 3 OH,a nd others. [5][6][7][8][9][10][11][12] Metal-N-C is at ype of attractive electrocatalyst for efficient CO 2 reduction to CO. Because of the ambiguity in their atomic structures, the active sites and catalytic mechanismso ft he catalysts have remained under debate. Here, the effects of Na nd Ch ybrid coordination on the activity of Ni-N-C catalysts were investigated,c ombining theoretical and experimental methods.…”