Efficient Conversion of CO₂to CO Using Tin and Other Inexpensive and Easily Prepared Post-Transition Metal Catalysts

Abstract

The development of affordable electrocatalysts that can drive the reduction of CO2 to CO with high selectivity, efficiency, and large current densities is a critical step on the path to production of liquid carbon-based fuels. In this work, we show that inexpensive triflate salts of Sn(2+), Pb(2+), Bi(3+), and Sb(3+) can be used as precursors for the electrodeposition of CO2 reduction cathode materials from MeCN solutions, providing a general and facile electrodeposition strategy, which streamlines catalyst synthesis. The ability of these four platforms to drive the formation of CO from CO2 in the presence of [BMIM]OTf was probed. The electrochemically prepared Sn and Bi catalysts proved to be highly active, selective, and robust platforms for CO evolution, with partial current densities of jCO = 5-8 mA/cm(2) at applied overpotentials of η < 250 mV. By contrast, the electrodeposited Pb and Sb catalysts do not promote rapid CO generation with the same level of selectivity. The Pb material is only ∼10% as active as the Sn and Bi systems at an applied potential of E = -1.95 V and is rapidly passivated during catalysis. The Sb-comprised cathode material shows no activity for conversion of CO2 to CO under analogous conditions. When taken together, this work demonstrates that 1,3-dialkylimidazoliums can promote CO production, but only when used in combination with an appropriately chosen electrocatalyst material. More broadly, these results suggest that the interactions between CO2, the imidazolium promoter, and the cathode surface are all critical to the observed catalysis.

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO2 to CO

“…12,15,45 The observed improvement in CO 2 conversion efficiency for the OD-Cu electrode in this study can be due to the careful acid pretreatment of the electrode, probably removing existing active species for H 2 , and the subsequent 400 °C annealing step, in contrast to the 500 °C heat treatment previously used to build the copper oxide layers. 12,21,45,46 Next, the electrocatalytic performance of Cu-Sn exhibited a remarkably high FE towards CO, achieving > ~90% at −0.6 V ( Figure 1b). A long-term stability of the Cu-Sn was observed for 14 h, which showed an initial ~95% CO FE for 6 h; subsequently decreasing to ~90%, with the H 2 FE increasing over time from ~8% to ~12%.…”

“…18 Rosenthal and co-workers have reported a generalized strategy for the electrodeposition of inexpensive electrocatalytic films from triflate salts of Bi 3+ , Sb 3+ , Sn 2+ , and Pb 2+ in organic media. [19][20][21] When the Bi-based electrodes are used for electrochemical CO 2 reduction in acetonitrile with a low overpotential of 250 mV, the 4 electrocatalysts are highly selective towards CO only when an appropriate ionic liquid is present in the system (1-ethyl-3-methylimidazolium hexafluorophosphate [EMIM]PF 6 , or 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]PF 6 , with an average 81% CO FE with [25][26][27][28][29][30] mA cm −2 ). [19][20][21] These seminal studies have thus clearly indicated that non-noble catalysts have the capability to compete with noble metals for CO 2 reduction.…”

Nanostructured nonprecious metal catalysts for electrochemical reduction of carbon dioxide

“…Except for Sn, partially oxidized Bi/Bi 3+ materials have shown excellent CO-selective capabilities in ionic liquid [121][122][123][124]. Recently, the Rosenthal group synthesized a rosebud-type Bi thin film on a glassy carbon electrode (GCE) by electrochemical deposition (Fig.…”

Hybrid bioinorganic approach to solar-to-chemical conversion

“…Elegant advances in traditional approaches to CO 2 reduction driven by electrical and/or solar inputs using homogeneous (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16), heterogeneous (17)(18)(19)(20)(21)(22)(23)(24)(25)(26), and biological (7,(27)(28)(29)(30)(31) catalysts point out key challenges in this area, namely (i) the chemoselective conversion of CO 2 to a single product while minimizing the competitive reduction of protons to hydrogen, (ii) long-term stability under environmentally friendly aqueous conditions, and (iii) unassisted light-driven CO 2 reduction that does not require external electrical bias and/or sacrificial chemical quenchers. Indeed, synthetic homogeneous and heterogeneous CO 2 catalysts are often limited by product selectivity and/or aqueous compatibility, whereas enzymes show exquisite specificity but are generally less robust outside of their protective cellular environment.…”