Boosting Electroreduction of CO₂over Cationic Covalent Organic Frameworks: Hydrogen Bonding Effects of Halogen Ions

Abstract

We present the first example of charged imidazolium functionalized porphyrin-based covalent organic framework (Co-iBFBim-COF-X) for electrocatalytic CO 2 reduction reaction, where the free anions (e.g., F À , Cl À , Br À , and I À ) of imidazolium ions nearby the active Co sites can stabilize the key intermediate *COOH and inhibit hydrogen evolution reaction. Thus, Co-iBFBim-COF-X exhibits higher activity than the neutral Co-BFBim-COF, following the trend of F À < Cl À < Br À < I À . Particularly, the Co-iBFBim-COF-I À showed nearly 100 % CO 2 selectivity at a low full-cell voltage of 2.3 V, and achieved a high CO 2 partial current density of 52 mA cm À 2 with a turnover frequency of 3018 h À 1 at 2.4 V in the anion membrane electrode assembly, which is 3.57 times larger than that of neutral Co-BFBim-COF. This work provides new insight into the importance of free anions in the stabilization of intermediates and decreasing the local binding energy of H 2 O with active moiety to enhance CO 2 reduction reaction.

Unleashing the power of directed electron transfer: unraveling the potential of {PV4}2 in heterogeneous photocatalysis

“…Besides, the current density of {PV 4 } 2 in CO 2 saturated electrolyte solution was higher than that of {PV 4 } 2 in Ar saturated electrolyte solution, indicating the current increase originated from the reaction of Carbon Dioxide Reduction (CO 2 RR). 31,32 The CO 2 gas adsorption data of the catalysts (Fig. 3i) was consistent with the Type I Langmuir adsorption model, 33,34 indicating that the adsorption behaviour was monolayer adsorption.…”

Single-Atom Catalysts on Covalent Organic Frameworks for Energy Applications

“…Recently, Huang et al reported a porphyrin-based Co-iBFBim-COF-X (X = F − , Cl − , Br − , I − ). 158 Co-iBFBim-COF-I exhibited a high FE(CO) of 99% at a low full-cell voltage of 2.3 V and achieved a high CO partial current density of 52 mA cm −2 with a TOF of 3018 h −1 at 2.4 V. The free halogen anions were beneficial in stabilizing the intermediates via hydrogen bonds and suppressed HER to increase selectivity toward CO 2 RR. Likewise, Liu et al synthesized CoTAPP-PATA-COF by using 5,10,15,20-tetrakis-(4aminophenyl)porphinato]cobalt [TAPP(Co)] and 4,4′,4″,4‴-[1,4-phenylenebis(azanetriyl)]tetrabenzaldehyde (PATA) as monomers (Figure 3k).…”

“…Ionic COFs benefit catalytic reactions by improving their electron conductivity and transfer. Recently, Huang et al reported a porphyrin-based Co-iBFBim-COF-X (X = F – , Cl – , Br – , I – ) . Co-iBFBim-COF-I exhibited a high FE(CO) of 99% at a low full-cell voltage of 2.3 V and achieved a high CO partial current density of 52 mA cm –2 with a TOF of 3018 h –1 at 2.4 V. The free halogen anions were beneficial in stabilizing the intermediates via hydrogen bonds and suppressed HER to increase selectivity toward CO 2 RR.…”

Boosting hydrogen peroxide production via establishment and reconstruction of single‐metal sites in covalent organic frameworks

“…[1][2][3][4][5][6][7] The atomic level predesign of these structures offers controllable porosity and assembled functional groups in two and three dimensions. [8][9][10][11][12] Moreover, COFs have been used in various applications, such as medical delivery, [13][14][15] gas adsorption and separation, [16][17][18] energy storage and conversion, [19][20][21][22][23][24][25][26] and heterogeneous catalysis [27][28][29][30][31] using different electrocatalytic building units, including metal porphyrins or phthalocyanines. They have also been extensively applied to the oxygen reduction reaction (ORR), [32][33][34][35][36][37] oxygen evolution reaction, [38][39][40][41] and CO 2 reduction reaction.…”