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The electrochemical CO2 reduction reaction (CO2RR) is a promising strategy to convert CO2 to carbon‐based fuels and to simultaneously reduce the emission of greenhouse gases into the atmosphere. In this work, the bismuth subcarbonate nanoflowers (BOC NFs) are facilely prepared through a one‐pot synthesis method for efficient formate electrosynthesis through CO2RR. Benefiting from the crystal structure and sheet‐stacked morphology, the in situ measurements and theoretical calculation results reveal the self‐reinforced CO2 adsorption properties and rapid CO2 adsorption–desorption kinetics on the catalyst surface, which significantly facilitate the CO2RR process. As a result, the desirable Faradaic efficiencies of over 90%, with a maximum value of 98.9%, toward formate formation, are achieved in a wide potential window from −0.8 to −1.4 V in an H‐type cell. Moreover, in a flow cell, the superior intrinsic activity of BOC NFs guarantees the high throughput electrocatalytic performance of CO2RR and the FEformate of over 90% with high current density is achieved in a potential range as wide as 1200 mV, demonstrating the great potential of BOC NFs for practical CO2RR applications. These results underscore the effectiveness of designing electrocatalysts with self‐reinforced CO2 adsorption properties to improve electrocatalytic performance for efficient CO2RR. [ABSTRACT FROM AUTHOR]

Highlights: B atoms modify the local electronic structure of Bi with positive valence sites. B doped Bi boosts highly efficient electroreduction of CO2 to formate. B dopant differentiates the proton participations in CO2 RR and HER processes. The dominant mechanistic pathway of B promoted formate generation is unraveled. Electrochemical reduction of CO2 to formate is economically attractive but improving the reaction selectivity and activity remains challenging. Herein, we introduce boron (B) atoms to modify the local electronic structure of bismuth with positive valence sites for boosting conversion of CO2 into formate with high activity and selectivity in a wide potential window. By combining experimental and computational investigations, our study indicates that B dopant differentiates the proton participations of rate-determining steps in CO2 reduction and in the competing hydrogen evolution. By comparing the experimental observations with the density functional theory, the dominant mechanistic pathway of B promoted formate generation and the B concentration modulated effects on the catalytic property of Bi are unravelled. This comprehensive study offers deep mechanistic insights into the reaction pathway at an atomic and molecular level and provides an effective strategy for the rational design of highly active and selective electrocatalysts for efficient CO2 conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • In species was integrated on CuO to directionally maximize CO selectivity using a facile method. • CO formation was initiated at an ultralow onset potential of −0.196 V vs. RHE. • A remarkably high CO Faraday efficiency of near-unity was achieved. • A slow reduction of CuO to metallic Cu caused by the In species guarantees an unprecedented stability for CO 2 RR. • The reasons credited for the enhanced CO 2 RR performance are systematically explored. CO 2 reduction reaction (CO 2 RR) is one of the most promising approaches to alleviating greenhouse gas effect and simultaneously producing value-added chemicals and has been widely studied in recent years. To this end, a composite of indium species on CuO (InO x @CuO) was facilely synthesized for CO 2 RR, and it is found that the selectivity of the target product could be accurately tuned through incorporating post-transition species with Cu-based materials; the desirable Faraday efficiencies of over 90%, with a maximum value of 97.8%, toward CO formation were achieved in a wide potential window from −0.3 to −0.7 V. Moreover, a high CO partial current density of 7.2 mA cm−2 and a long-term stability of 50 h with negligible degradation were obtained over InO x @CuO. More importantly, CO starts to be observed at an ultralow potential of −0.196 V, further confirming the excellence of InO x @CuO for CO 2 RR toward CO formation. The results demonstrate that the achieved superiority derives from the essential In species on CuO, which not only introduces more active sites, but also better stabilizes the key intermediates, accelerates electron transfer and increases CO 2 adsorption. [ABSTRACT FROM AUTHOR]

• Cu 2 Se/Co 3 Se 4 multivalent hetero-nanocrystals are fabricated as efficient electrocatalysts. • Interfacial engineering facilitates rapid charge transfer at Cu–Se–Co hetero-interfaces. • Highly-selective methanol conversion to value-added formate is achieved at much low potential. • Energy saved generation of pure hydrogen as only gas product avoids O 2 /CO 2 emission. • In-situ formed Cu*/Co*−OOH and SeO x species act as synergistic active sites for methanol upgrading. Integrating organic upgrading and hydrogen electrolysis is recently regarded as a win-win strategy. However, it is still challenging to construct efficient robust electrocatalysts to considerably minimize their energy demand for such coupled reaction and simultaneously avoid the emission of environment-unfriendly CO 2. Herein, the Cu 2 Se/Co 3 Se 4 multivalent hetero-nanocrystals (CuCoSe-HNCs) are fabricated as efficient electrocatalysts through interfacial engineering, thus constructing abundant hetero-junctions on monodispersed CuCoSe-HNCs and facilitating the charge transfer at Cu–Se–Co hetero-interfaces. DFT studies reveal the multivalent CuCoSe-HNCs with hydroxylated surfaces, which possess complex species (Cu*−OOH, Co*−OOH, and SeO x) as synergistic active centers, thus effectively optimizing the surface adsorption/dissociation performance and suppress excessive oxidation to CO 2. Hence, the methanol upgrading conversion to value-added formate is achieved at much low working potential (1.11V) with high faradaic efficiency (>98 %) and without CO 2 emission, thus considerably decreasing the energy consumption for generating the only gas product of pure hydrogen. [ABSTRACT FROM AUTHOR]

Perovskites are the promising catalysts for various reactions, yet their structure evolutions and the composition-function relation in the carbon dioxide reduction reaction (CO 2 RR) are not fully explored. In this study, we report that the reconstructed BaBiO 3 (BBO) perovskite is able to facilitate CO 2 -to-formate (FA) conversion by both A- (Ba) and B- (Bi) site elements through the cooperative but distinct catalytic mechanisms. Specifically, the electrochemical reductions of BBO trigger the complete rearrangement of atoms with rapid kinetics at catalytically relevant voltages, giving rise to electricity-induced Bi metallene (eBBO) that efficiently generates FA with high selectivity and partial current densities. Moreover, the reconstructed BBO simultaneously enables Ba2+ release to the electrolyte, and the time-resolved FTIR and in situ Raman analysis collectively reveal that the Ba2+ adsorption enables easier CO 2 adsorption, thereby leading to enhanced CO 2 -to-FA conversion. This work is of direct significance in elucidating the cooperative catalysis between A- and B- site elements in perovskites for room-temperature CO 2 RR. [Display omitted] • Potential-induced reconstructions of BaBiO 3 lead to the in situ generation of bismuthene. • BaBiO 3 derived bismuthene exhibits high activity towards CO 2 -to-Foramte (FA) conversion. • A photoelectrochemical cell was constructed to initiate FA production at a low cell voltage of 2.5 V with high selectivity. • The simultaneous release of A-site element (Ba2+) into the electrolyte promotes the CO 2 adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • OH− ions were created by the in-situ synthesis of CdCO 3 (i-CdCO 3) on the electrode. • The i-CdCO 3 delivers near-unity selectivity for the electroreduction of CO 2 to CO. • An ultrahigh mass activity of 165.1 mA mg−1 was achieved on i-CdCO 3 at − 1.26 V. • The superior CO selectivity is due to an increased local pH which inhibits HER. Electrochemical reduction of CO 2 to CO is an attractive approach for the sustainable carbon cycle. However, the activity and selectivity of the CO 2 reduction reaction (CO 2 RR) are often limited by the competitive hydrogen evolution reaction (HER) in aqueous media. In this work, in-situ generated hydroxides were introduced by the synthesis of rhombohedral CdCO 3 crystals (i-CdCO 3) under electrochemical CO 2 RR conditions. The generated hydroxides contribute to an increased local pH at the electrode/electrolyte interface, thereby effectively inhibiting HER. As a result, the obtained i-CdCO 3 exhibits remarkably higher CO Faradaic efficiency (over 90%) in a broad potential range, where a near 100% selectivity is achieved, as compared to a pre-synthesized CdCO 3 with similar morphology. Moreover, i-CdCO 3 delivers a large current density of − 24.8 mA mg−1 at − 1.26 V, together with a good stability of 36 h with negligible degradation, further demonstrating its superiority for efficient CO 2 RR. This study proposes a promising design strategy to boost the selectivity of CO 2 RR systems through in-situ producing hydroxides near the electrode to suppress the unfavorable HER. [ABSTRACT FROM AUTHOR]