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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]

Photo‐thermochemical cycle (PTC) is a promising method to converting CO2 to solar fuels. To study the mechanism of CO2 reduction based on PTC, sol‐gel synthesized titanium dioxide (ST) and Mn‐doped TiO2 (MT) films were produced and applied to the PTC under simulated solar light irradiation. Commercial P25 (PT) was used as a reference. Experiments show that Mn‐doped TiO2 produced more CO than undoped TiO2 and P25. The average CO production of 1.0 wt% MT by the PTC was 32.19 μmol⋅m−2⋅h−1), 4.36 times than that of ST and 3.63 times that of PT. Various characterization methods were conducted to investigated the effect of Mn ions doping on the photoresponse and charge transfer of samples. Density functional theory (DFT) calculations were also performed to verify the analysis and enhance the PTC mechanism. In conclusion, several key factors that Mn ions promote CO2 conversion have been clarified. Combine solar heat and light! To reduce CO2, photo‐thermochemical (PTC) cycle involves both solar light and thermal energy. Photo‐induced oxygen vacancy (VO) is the key to reduce CO2 in thermal step. Introducing Mn to TiO2 significantly broadens its visible light response and decreases the VO formation energy by DFT calculations. Experimental results show that doping TiO2 with Mn significantly enhances CO2 reduction by PTC under simulated solar light irradiation. [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]

Converting solar energy into chemical fuels can effectively match existing energy structures and mitigate climate change. An oxygen vacancies (Vox) based photo-thermochemical (PTC) method has characteristics of both photochemistry and thermochemistry, making it possible to use both solar light and heat. In this paper, perovskite oxide catalysts were prepared by a solvothermal method. Multiple experiments and characterizations were performed to investigate the reaction process. We also performed FDTD simulations to illustrate the plasmonic characteristics of the materials in the PTC. With the existence of Au nanoparticles, the stable production of CO had a maximum value of 7.28 μmol/g h, achieved by 1.5 gold-nanoparticle-loaded SrTiO 3. Visible light-responding Au-SrTiO 3 catalysts for photo-thermochemical CO 2 reduction. Unlabelled Image • PTC convert solar light and heat simultaneously to produce solar fuels. • Perovskite was used as a promising catalyst for PTC. • SrTiO 3 with Au nanoparticles loaded showed the ability to harvest the visible light by LSPR. [ABSTRACT FROM AUTHOR]