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In this work, to achieve both clean energy production and carbon emission reduction, a united conversion to couple CO 2 mineralization with thermochemical hydrogen production is proposed. Natural magnesium silicate minerals are used to fix CO 2 in the form of carbonate minerals, whereas H 2 O is dissociated to produce H 2 in the thermochemical cycle. The integration provides a new solution to the challenges of the high energy consumption and poor economic value of conventional CO 2 mineralization processes, and the technical feasibility has been proven. Moreover, the energy economy and CO 2 conversion capacity were investigated. Hydrolyzation and carbonation experiments were performed in a homemade reactor, and it was found that an optimal MgI 2 hydrolyzation rate of 75% could be achieved without alkali consumption. A detailed simulation of the whole system was also developed. The optimal energy conversion efficiency of the cycle reached 47.6%, which is higher than most of the published theoretical energy efficiency values for sulfur-iodine thermochemical cycles. A modified calculation of the net energy requirement for CO 2 mineralization was carried out. Finally, a comparison and an evaluation of the energy efficiencies were made based on the calculation. In the optimal case, the modified net energy requirement is 1.4 MJ/kg CO 2 , which means that this method is competitive compared to those of previous works.

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]

To dissociate carbon dioxide (CO 2 ) using solar energy, a novel photo-thermochemical cycle combining photochemistry with thermochemistry is proposed in this paper. After illuminating titanium dioxide (TiO 2 ) in a helium (He) atmosphere by ultraviolet (UV) irradiation, CO 2 was input and converted to carbon monoxide (CO) under heating in an enclosed cavity. To determine the optimal heating temperature, sets of four consecutive cycles were performed at temperatures from 573 K to 873 K. The preferred temperature was found to be 773 K. CO was stably produced in five successive cycles at 773 K, demonstrating the method’s possibility. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) were employed to assess the crystal structure and morphology. X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) analyses were also conducted to investigate the charge transfer and reaction mechanisms on the TiO 2 surface. Finally, a charge transfer mechanism is tentatively proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A wavelength-dependent local field was constructed to greatly enhance CO 2 adsorption and key intermediates formation. • The CO/H 2 ratio could be adjusted from 0.65 to 1.84 by adjusting LSPR intensities of samples. • An unbiased solar-to-gaseous-carbon-fuel (SGCF) efficiency of 0.51 % could be achieved. • CO, CH 4 and formate can be stably produced with using a neutral solution based on low-cost metal oxides. • Both internal and interfacial charge carrier transfer can be enhanced to avoid energy loss of recombination. The fabrication of an efficient and low-cost photocathode still remains a big challenge. We herein report a Ag/Cu x O@rGO/Mo photocathode for CO 2 conversion. A unique wavelength-dependent performance is found to enhance the formation of the key intermediate groups by exciting photothermal local surface plasmonic resonance (LSPR) using the lights with wavelengths ranging from 550 to 600 nm. CO, H 2 and CH 4 can be stably produced with dual photoelectrodes using a neutral solution. An unbiased solar-to-gaseous-carbon-fuel efficiency (SGCF) of 0.51 % has been achieved, which sets a record for carbon gas fuel production with binary photoelectrodes. In addition, the CO/H 2 ratio could be tuned in the range from 0.65 to 1.84, which makes it possible to fine tune the syngas production. The excellent PEC CO 2 reduction capability achieved by the new wavelength-dependent catalytic route may shine some lights for the future design and development of the next-generation PEC materials and devices. [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]