Metallo-porphyrin complexes such as cobalt and iron porphyrins (CoP and FeP) have shown potential as electrocatalysts for CO 2 reduction. Here we report that introducing amino substituents enhances the electrocatalytic activity of these systems toward CO 2 reduction through a dual active site approach. We developed a flexible synthesis of Coand Fe-porphyrins having variable amino groups and found that monoamino FeP reduces CO 2 to carbon monoxide (CO) at ambient pressure and temperature with competitive turnover numbers (TONs). This efficiency enhancement approach opens a new path to designing and optimizing next generation homogeneous catalysts.

B(npy)Ar 2 (npy = 2-(naphthalen-1-yl)pyridine) compounds bearing various nonbulky aryl groups undergo ac lean and sequential two-step photoisomerization in which two aryl substituents on boron migrate to acarbon atom of the naphthyl moiety.T he second isomerization step is the first example of areversible photoisoermization between aborepin and ab orirane.B oth steric and electronic factors have been found to have ag reat impact on this photoreactivity.F urthermore,t he borirane isomer reacts with oxygen, forming ar are oxaborepin dimer.

Electrochemical reduction of carbon dioxide (CO2) is a sustainable solution to conversion of CO2 into value-added products such as hydrocarbons and carbon monoxide (CO). However, designing high-efficiency molecule-based electrocatalysts is challenging. In this work, we designed and synthesized iron-porphyrin-pyridine (Fe-TPPy) catalysts in a strategy that combined molecular design and a nanoscale approach. The catalytic activity of these compounds toward CO2 reduction was evaluated under both homogeneous and heterogeneous conditions. Tuning of Fe-TPPy with anisole electron-donating substituents improved the catalytic efficiency up to 76% with a current density of −1.3 mA/cm2 and a turnover frequency (TOF) of 1 s–1. The faradaic efficiency was further enhanced to 92% with a current density of −30 mA/cm2 and a TOF of 5 s–1 after immobilization of the porphyrins onto carbon nanotubes. Density functional theory calculations confirmed that the push–pull pyridine–anisole interaction facilitates CO2 binding, resulting in an enhancement of the overall catalytic efficiency. This work provides an effective strategy for improvement of electrocatalytic performance that could inspire the design of future molecular catalysts.

Electrochemical reduction of carbon dioxide (CO 2 ) is a viable solution for conversion of atmospheric CO 2 to value-added materials such as carbon monoxide (CO). In this project, a new urea iron-tetraphenylporphyrin-dimer (Fe-TPP-Dimer) was synthesized and applied for electrocatalytic CO 2 reduction under both homogeneous and heterogeneous conditions to selectively reduce CO 2 to CO. Immobilization of the catalyst onto carbon nanotubes (CNTs) in aqueous solution resulted in remarkable enhancement of its electrocatalytic abilities, with exceptional turnover frequencies (10 s À 1 ), high faradic efficiency (FE) of ∼ 90%, and a current density of 16 mA/cm 2 at À 0.88 V vs. RHE. This project exhibits the importance of molecular design in accessing heterogeneous applications with CNTs.Consumption of fossil fuels for energy production in recent decades has dispensed alarming amounts of carbon dioxide (CO 2 ), one of the leading contributors to climate change, into the atmosphere. [1][2][3][4][5] Although the capture and conversion of CO 2 to value-added synthons has become a desirable solution to this problem, challenges in regard to the species' general lack of reactivity and the costs associated with deployment and stability of such strategies remain prevalent. [6][7][8][9][10][11] In this respect, electrocatalytic CO 2 reduction reactions (CO 2 RRs) pose a promising alternative to this end. [12][13][14][15][16][17][18][19][20] Extensive research has been conducted on both homogeneous and heterogeneous molecular catalysts for CO 2 RR. [21][22][23][24] Although homogeneous catalysts are popular for CO 2 RR application, applying heterogeneous catalysts is essential for emerging of CO 2 to CO conversion in large scale. Additionally, most molecular catalysts favor non-aqueous solvents such as N,N-dimethylformamide (DMF) and acetonitrile, making them more costly to implement. [25][26][27] Immobilization of molecular catalysts onto electrode surfaces can occur via several methods which include covalent bonding, [28,29] non-covalent attachment, [30,31] and surface polymerization. , [32,33] Among them, non-covalent surface binding methods that capitalize on strong Van der Waals π-π interactions between carbon surfaces and polyaromatic hydrocarbon moieties is easily accomplished and displays great surface stability, [31,34] making it a favorable technique for immobilization. [30,[35][36][37][38] Carbon nanotubes (CNTs) are of particular interest for CO 2 electroreduction owing to their high stability, conductivity and large surface area. [19,31,[39][40][41][42] Among transition metal complexes, iron, [24,25,[43][44][45] cobalt [46][47][48] and nickel, [49][50][51] are prevailing and more environmentally friendly than other metals used for CO 2 RR application. Metalloporphyrin catalysts are attractive as molecular catalysts in this field because of their robust structure and their stability to harsh conditions such as high temperatures. [52] Demonstrative work by Savéant showed that iron tetraphenylporphyrin (Fe-TPP) complexe...

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The ever-growing levels of carbon dioxide (CO2) in our atmosphere, is at once a threat and an opportunity. The development of sustainable and cost-effective pathways to convert CO2 to value-added...

B(npy)Ar 2 (npy = 2-(naphthalen-1-yl)pyridine) compounds bearing various nonbulky aryl groups undergo ac lean and sequential two-step photoisomerization in which two aryl substituents on boron migrate to acarbon atom of the naphthyl moiety.T he second isomerization step is the first example of areversible photoisoermization between aborepin and ab orirane.B oth steric and electronic factors have been found to have ag reat impact on this photoreactivity.F urthermore,t he borirane isomer reacts with oxygen, forming ar are oxaborepin dimer.