Significantly improved electrocatalytic oxygen reduction by an asymmetrical Pacman dinuclear cobalt(ii) porphyrin–porphyrin dyad

Abstract

Asymmetrical Pacman dinuclear Co bisporphyrin shows significantly improved activity and selectivity for catalytic reduction of O2 to water in comparison with corresponding mononuclear Co porphyrins and symmetrical dinuclear Co bisporphyrins.

Controlling Oxygen Reduction Selectivity through Steric Effects: Electrocatalytic Two‐Electron and Four‐Electron Oxygen Reduction with Cobalt Porphyrin Atropisomers

“… [42, 43] Due to the presence of both paths, Co complexes usually show poor or moderate selectivity for either 2 e − or 4 e − ORR. For examples, Co porphyrins have been largely studied as ORR catalysts by displaying high activity but poor selectivity [36] . To improve selectivity, extensive efforts have been made to synthesize Co porphyrin cages with isolated Co sites [40] for 2 e − ORR and dinuclear Co porphyrins [34–38] for 4 e − ORR, in which peroxo‐bridged Co porphyrins are proposed as intermediates (Scheme 1 b).…”

“…[8][9][10] Recently, many molecular ORR catalysts have been reported. [1][2][3][4][5][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Although achievements have been made in improving the 4 e À ORR by providing rapid electron and proton transfers, [17,29,30] introducing hydrogenbonding [31,32] and electrostatic interactions, [33] and using dinuclear cooperation, [34][35][36][37][38] realizing these functionalities is challenging from both design and synthesis points of view. Unlike 4 e À ORR, few studies have been dedicated to improving the 2 e À ORR.…”

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

“…We herein report MOF‐supported Co porphyrins as catalysts for oxygen electrocatalysis. Co porphyrins are active and robust for electrocatalytic ORR, which is a significant process in many new energy conversion technologies, including fuel cells and metal–air batteries [34–41] . Through ligand exchange, [42–45] we can graft Co porphyrins on MOF surfaces (Figure 1 c), considering the following benefits of using MOFs as supports [46–53] .…”

Metal–Organic‐Framework‐Supported Molecular Electrocatalysis for the Oxygen Reduction Reaction

“…Co porphyrins are active and robust for electrocatalytic ORR, which is a significant process in many new energy conversion technologies, including fuel cells and metal-air batteries. [34][35][36][37][38][39][40][41] Through ligand exchange, [42][43][44][45] we can graft Co porphyrins on MOF surfaces (Figure 1 c), considering the following benefits of using MOFs as supports. [46][47][48][49][50][51][52][53] First, with different metals and organic linkers, the compositions of MOFs can be modified to make diverse hybrids.…”