Probing dissolved CO ₂ (aq) in aqueous solutions for CO ₂ electroreduction and storage

Abstract

CO 2 dissolved in aqueous solutions CO 2 (aq) is important to CO 2 capture, storage, photo-/electroreduction in the fight against global warming and to CO 2 analysis in drinks. Here, we developed microscale infrared (IR) spectroscopy for in situ dynamic quantitating CO 2 (aq). The quantized CO 2 (g) rotational state transitions were observed to quench for CO 2 (aq), accompanied by increased H 2 O IR absorption. An accurate CO 2 molar extinction coefficient ε was derived for in situ CO 2 (aq) quantification up to 58 atm. We directly measured CO 2 (aq) concentrations in electrolytes under CO 2 (g) bubbling and high-pressure conditions with high spectral and time resolutions. In KHCO 3 electrolytes with CO 2 (aq) > ~1 M, CO 2 electroreduction (CO 2 RR) to formate reached >98% Faradaic efficiencies on copper (Cu 2 O/Cu)–based electrocatalyst. Furthermore, CO 2 dissolution/desolvation kinetics showed large hysteresis and ultraslow reversal of CO 2 (aq) supersaturation in aqueous systems, with implications to CO 2 capture, storage, and supersaturation phenomena in natural water bodies.

Pressure dependence in aqueous-based electrochemical CO2 reduction

“…However, industry works exclusively with pressurized CO 2 (PCO 2 ) in capture, transport and storage. In many such cases, the CO 2 is in dissolved form (1 -110 bar) 13,14 . PCO 2 is also the e uent of various industrial processes, such as natural gas reforming and ethylene oxide production (3 -20 bar) 15,16 .…”

Multiscale CO2 Electrocatalysis to C2+ Products: Reaction Mechanisms, Catalyst Design, and Device Fabrication

“…Although rational manipulation of active sites in electrocatalysts and electrodes could largely facilitate the CO 2 RR rate, the macroscale electrolyzer assembly remains uncontrollable given that little understanding has been achieved on the operation conditions and high-throughput experimentation in electrolyzer scale. − With recent achievements regarding electrolyzer assembly technology, the CO 2 RR represents a promising energy conversion route to generate valuable carboneous fuels and chemicals toward practical application in industrial levels. , …”

Spintronic filter via p-typed polaron state in photoelectron conversion integrating devices

“…For current energy-conversion semiconductor material selection, cuprous oxide (Cu 2 O) gives a promising performance in CO 2 conversion and water-splitting devices. [20][21][22][23][24] Regarding the issues of CO 2 electron reduction, Cu 2 O has demonstrated >98% faradaic efficiencies on copper (Cu 2 O/Cu)-based electrocatalysts. 21 In water-based electrolytes, with the specic oxidation state (polaron surface state) of the CeO 2 /Cu 2 O/Cu (111) catalyst, high selectivity was demonstrated to convert CO and CO 2 to methanol.…”

“…[20][21][22][23][24] Regarding the issues of CO 2 electron reduction, Cu 2 O has demonstrated >98% faradaic efficiencies on copper (Cu 2 O/Cu)-based electrocatalysts. 21 In water-based electrolytes, with the specic oxidation state (polaron surface state) of the CeO 2 /Cu 2 O/Cu (111) catalyst, high selectivity was demonstrated to convert CO and CO 2 to methanol. 25 However, to address water-splitting issues, Liu et al attempted to combine Ag and ZnO with Cu 2 O to form a triple-junction photoelectrode; the highest current density achieved by this system was 1.4 mA cm −2 , while the current density of pure Cu 2 O photoelectrode was only as high as 0.3 mA cm −2 .…”