Regulation of Coordination Number over Single Co Sites: Triggering the Efficient Electroreduction of CO₂

Abstract

The design of active, selective, and stable CO reduction electrocatalysts is still challenging. A series of atomically dispersed Co catalysts with different nitrogen coordination numbers were prepared and their CO electroreduction catalytic performance was explored. The best catalyst, atomically dispersed Co with two-coordinate nitrogen atoms, achieves both high selectivity and superior activity with 94 % CO formation Faradaic efficiency and a current density of 18.1 mA cm at an overpotential of 520 mV. The CO formation turnover frequency reaches a record value of 18 200 h , surpassing most reported metal-based catalysts under comparable conditions. Our experimental and theoretical results demonstrate that lower a coordination number facilitates activation of CO to the CO intermediate and hence enhances CO electroreduction activity.

A Hybrid Co Quaterpyridine Complex/Carbon Nanotube Catalytic Material for CO2 Reduction in Water

“…In the former case,s ubstituted Co phthalocyanine with 8c yano groups led to 5.6 mA cm À2 at 340 mV overpotential (TOF 1.4 s À1 )a nd 88 %C Os electivity,w hile an optimized CO selectivity of 98 %( TOFo f4 .1 s À1 )w as obtained at 520 mV overpotential with ac atalyst loading more than 5t imes larger than ours (Table 2, entry 4, CoPc-CN). Moreover,[Co(qpy)] 2+ also closely matches some of the most active solid electrocatalysts,i ncluding noble metals.A recent class of emerging catalytic materials is given by graphene type materials with atomically dispersed metal atoms,i ncluding notably Ni [21,22] and Co. [23] With cobalt, CO selectivity up to 94 %w as obtained at 520 mV overpotential (TOF 5s À1 )w ith ac urrent density of 18 mA cm À2 ,w hile comparable performances were recently achieved using nickel with selectivity in the range of 95 %a nd current density from 10 to 22 mA cm À2 (TOF from 4.1 to 6.8 s À1 )a t overpotential close to 600 mV.R egarding noble metals, nanostructured silver catalyst can achieve 9mAcm À2 (90 % selectivity) at 390 mV overpotential. [24] Oxide-derived Au nanoparticles can furnish 10 mA cm À2 at only 260 mV overpotential, [25] while state-of-the art gold nanoneedles give aCO current up to 22 mA cm À2 at only 240 mV overpotential ( Table 2, entry 6).…”

Engineering the Coordination Environment of Single‐Atom Platinum Anchored on Graphdiyne for Optimizing Electrocatalytic Hydrogen Evolution

“…[14,15] ForSACs, the coordination environments of metal atoms will greatly influence their electronic structures,a nd subsequently affect their catalytic activity. [18] Though the coordination environments of metal atoms are closely related to their catalytic activity in SACs, there is rare investigation for the influence of Pt atoms coordination environments on their catalytic activity of HER in Pt SACs.T ob etter understand the structure-activity relationship between the coordination environment of Pt atoms and the corresponding HER catalytic activity in Pt SACs,i ti si mperative to disperse the individual Pt atoms on as table support with adjustable coordination environments. Herein, we put forward asimple method for the synthesis of two Pt SACs on the support of graphdiyne (GDY). [17] Wu and co-workers constructed aseries of Co SACs with different nitrogen coordination numbers,a nd they found that atomically dispersed Co with two coordinate nitrogen atoms displays the best CO 2 electroreduction catalytic performance.…”

Isolated Diatomic Ni‐Fe Metal–Nitrogen Sites for Synergistic Electroreduction of CO2

“…[2] Single-atom catalysts (SACs) with fully exposed, highly selective,a nd well-defined active sites have great potential to tackle these challenges in CO 2 reduction reaction (CO 2 RR). Ni, Fe, Co) anchored on nitrogenated carbon are ag ood example and they have demonstrated impressive activity for CO 2 RR yielding CO. [4] Theo verall conversion process is proposed to occur in three steps: [5] 1) CO 2 + H + + e À ! Ni, Fe, Co) anchored on nitrogenated carbon are ag ood example and they have demonstrated impressive activity for CO 2 RR yielding CO. [4] Theo verall conversion process is proposed to occur in three steps: [5] 1) CO 2 + H + + e À !…”