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The direct electrochemical conversion of captured CO2 (capt-eCO2R) into valuable chemicals has recently emerged as a promising carbon capture and utilisation technology that will contribute to achieving net-zero carbon emissions. Conventional electrochemical CO2 (eCO2R) typically uses pure CO2 gas as a reactant; thus, this system requires substantial energy and capital allocation across the entire process, from the initial CO2 capture to the post-CO2 conditioning for product separation. The capt-eCO2R addresses these limitations and presents a compelling economic advantage by integrating the CO2 capture and direct electro-conversion of captured CO2 in the form of carbamate and (bi)carbonate without a CO2 conditioning process. The capt-eCO2R is still in the early stages of development and is not as mature as the conventional eCO2R; thus, several challenges remain to be addressed to improve system performance. This review provides a comprehensive overview of the capt-eCO2R system, including various system configurations, suitable catalysts, and strategies to enhance performance within captured media. The reaction mechanisms depend on the form of captured CO2; therefore, we categorised them according to the type of CO2 absorbent. The outlook, ongoing challenges, and strategies for future development are also presented. [ABSTRACT FROM AUTHOR]

Maleic acid (MA) production from furfural (FF) is a promising electrochemical oxidation reaction to convert biomass into valuable platform chemicals. However, a library of oxidation activities needs to be studied more. Herein, we demonstrate that Bi doping in lead oxide is effective in tuning the activity for complicated FF oxidation reactions. Bi-doped lead oxide (PbBiOx) can selectively produce MA from the electrochemical FF oxidation reaction (FFOR), leading to a maximum MA yield of 57% with an optimal Bi content of Pb0.9Bi0.1Ox. Its selectivity, the relative yield of MA in relation to 5-hydroxy-2(5H)-dihydrofuran-2-one (HFN), is largely enhanced by 17 times, compared to pristine PbOx. We propose that Bi affects the oxidation state of Pb and thus the selectivity of the oxidation reaction, which is supported by a series of product analyses of the electrochemical oxidation of FF (reactant), HFN (intermediate), and maleic acid (product). While PbOx prepared by a simple thermal decomposition method is composed of a PbO2 and Pb3O4 mixture, the ratio of PbO2 to Pb3O4 decreases in PbBiOx, suppressing active Pb4+ under the applied potentials. PbBiOx exhibited a lower conversion rate of FF as well as greater preservation of the carbon source during the FFOR than PbOx, and Bi-doping was also shown to be effective in retarding the overoxidation of MA to CO2. Our study shows that mixed metal oxides can be effective in adjusting the oxidation activity and contribute to selective electrosynthesis from multi-step biomass conversion. [ABSTRACT FROM AUTHOR]

Cations in an electrolyte modulate microenvironments near the catalyst surface and affect product distribution from an electrochemical CO 2 reduction reaction, and thus, their interaction with intermediate states has been tried to be probed. Herein, we directly observed the cation effect on *CO intermediates on the Cu(OH) 2 -derived catalyst in real time through operando surface-enhanced Raman spectroscopy at high overpotentials (-1.0 V RHE ). Atop *CO peaks are composed of low-frequency binding *CO (*CO LFB ) and high-frequency binding *CO (*CO HFB ) because of their adsorption sites. These two *CO intermediates are found to have different sensitivities to the cation-induced field, and each *CO is proposed to be suitably stabilized for efficient C-C coupling. The proportions between *CO HFB and *CO LFB are dependent on the type of alkali cations, and the increases in the *CO HFB ratio have a high correlation with selective C 2 H 4 production under K + and Cs + , indicating that *CO HFB is the dominant and fast active species. In addition, as the hydrated cation size decreases, *CO LFB is more sensitively red-shifted than *CO HFB , which promotes C-C coupling and suppresses C 1 products. Through time-resolved operando measurements, dynamic changes between the two *CO species are observed, showing the rapid initial adsorption of *CO HFB and subsequently reaching a steady ratio between *CO LFB and *CO HFB .