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The community of electrochemical CO 2 reduction is almost exclusively focused on gaseous CO 2 -fed electrolyzers. Here, we proposed a pressurized CO 2 -Captured solution electrolyzer to produce solar Fuel of CO (abbreviated "CCF") without the need to regenerate gaseous CO 2 . Specifically, we developed an experimentally validated multiscale model to quantitatively investigate the effect of pressure-induced chemical environment and to resolve the complex relationship between this effect and the activity and selectivity of CO production. Our results show that the pressure-induced variation of the cathode pH has a negative effect on the hydrogen evolution reaction, whereas the species coverage variation positively affects CO 2 reduction. These effects are more pronounced at pressures below 15 bar (1 bar = 101 kPa). Consequently, a mild increase in the pressure of the CO 2 -captured solution from 1 to 10 bar leads to a dramatic enhancement in selectivity. Using a commercial Ag nanoparticle catalyst, our pressurized CCF prototype achieved CO selectivity higher than 95% at a low cathode potential of -0.6 V versus reversible hydrogen electrode (RHE), comparable to that under the gaseous CO 2 -fed condition. This enables the demonstration of a solar-to-CO efficiency of 16.8%, superior to any known devices with an aqueous feed., Competing Interests: Conflicts of interest The authors declare that they have no conflict of interest., (Copyright © 2023 Science China Press. Published by Elsevier B.V. All rights reserved.)

Electrochemical CO 2 conversion into valuable products provides a promising solution for achieving a carbon-neutral energy cycle. Herein, an active and stable Bi/Nafion interface is fabricated over Bi nanosheets with the modification of Nafion, which exhibits superior CO 2 conversion with formate selectivity of above 95% in a wide potential range, partial current density of 72.12 mA cm−2 at − 1.07 V vs. RHE in H-type cell. The extraordinary CO 2 reduction performance could be ascribed to a high CO 2 permeability and enhanced local proton activity at the Bi/Nafion interface, which leads to promoted CO 2 adsorption and feasible proton-coupled electron transfer during the CO 2 reduction process. Computational investigations reveal the modification of Nafion offers a comfortable platform to enable the key intermediate *OCHO to be stable. This work offers a valuable insight into interfacial manipulation of electrodes to convert CO 2 to valuable products. [Display omitted] • An efficient strategy of a stable, active Bi/Nafion interface was proposed and realized by Nafion modification. • The Bi/Nafion interface exhibits the high performance of electrochemical CO 2 reduction to formate. • The Bi/Nafion interface shows promoted CO 2 adsorption and enhanced local proton activity. • Nafion acts as a protective layer to ensure the stability of the electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] We demonstrated an efficient solar photovoltaic-powered electrochemical CO 2 reduction device with a high-pressure CO 2 -captured liquid feed. In an "air-to-barrel" picture, this device holds promise to avoid both high-temperature gaseous CO 2 regeneration and high energy-cost gas product separation steps, while these steps are necessary for devices with a gaseous CO 2 feed. To date, solar fuel production with a CO 2 -saturated liquid feed suffers from high over-potential to suppress the hydrogen evolution reaction and consequently, low solar-to-chemical (STC) energy conversion efficiency. Here, we presented a distinct high-pressure operando strategy, i.e., we took extra advantage of the high pressure in catalyst synthesis besides in the period of the CO 2 reduction reaction (CO 2 RR). The power of this strategy was demonstrated by a proof-of-concept device in which a representative copper catalyst was first synthesized in operando in a high-pressure (50 bar) CO 2 -saturated KHCO 3 solution, and then this high-pressure CO 2 -captured liquid was converted to solar fuel using the operando synthesized Cu catalyst. This Cu catalyst achieved 95% CO 2 RR selectivity at the recorded low potential of −0.3 V vs. RHE enabled by the combination of operando facet engineering and oxide derivation. Furthermore, this device achieved a record-high STC efficiency of 21.6% under outdoor illumination, superior to other CO 2 -saturated liquid-fed devices, and compared favorably to gaseous CO 2 -fed devices. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO 2 represents an environmental-friendly process that could alleviate the environmental and energy crisis by eliminating greenhouse gasses and generating value-added chemicals. However, industrial-level CO 2 reduction to CO suffers from low CO 2 -conversion efficiency. To address this issue, this work proposes to use acidic electrolytes to avoid carbonate/bicarbonate salt precipitation, and shell for local CO 2 adsorption to improve its utilization and thus facilitate electroconversion. An Ag-based metal-organic framework (MOF) is hybridized with Ag, which exhibits near-unity selectivity to CO at an industrial-level current density (500 mA cm−2) in acidic media, robust electrochemical stability (100 h) and more importantly, high CO 2 conversion efficiency of 42.5 %. Fundamentally, CO 2 molecules are activated by Ag-MOF via atop adsorption of *CO after uptake by the porous organic complexes. The extraordinary performance originates from multi-scale regulation of CO 2 transport from the gas-diffusion layer to the local CO 2 adsorption shell near the atomic Ag active center of Ag-MOF. For Table of Contents only [Display omitted] [ABSTRACT FROM AUTHOR]

This work reports a facile procedure to regulate the size of Bi 2 WO 6 nanolayers by adjusting their Zeta potentials in aqueous dispersions. The as-resultant small-size Bi 2 WO 6 nanolayers have exhibited excellent structural characteristics like highly exposed metal active sites and large surface areas, which are favorable for converting CO 2 to formate. At the applied potential of −0.9 V (vs. RHE), the small-size Bi 2 WO 6 nanolayers have demonstrated the maximum FE of 82.3% with a current density of 106.1 mA cm−2 in a flow-type electrochemical cell. Further mechanism study had been achieved by using density functional theory (DFT) computations that highlight the potential-limiting step of CO 2 *➔ OCHO* that reveals the presence of *COOH intermediates adsorbed on the catalyst surface during the electrocatalysis process. • A general procedure has been demonstrated to regulate the size of two-dimensional nanolayers in aqueous dispersions. • The as-produced small-size Bi2WO6 nanolayers have exhibited excellent activities for converting CO2 to formic acid. • Density function theory (DFT) calculations highlighte the potential-limiting step of CO2*➔ OCHO* for CRR. • In situ Raman tests have been performed to probe the change of intermediates adsorbed on Bi2WO6 during CRR. [ABSTRACT FROM AUTHOR]