Sn based materials, as low-cost and earth-abundant electrocatalysts, are potential candidates for CO₂ reduction reaction (CO₂RR) into liquid fuels. Unfortunately, the low selectivity and stability limits their applications. Herein, we developed an electrocatalyst of Sn quantum dots (Sn-QDs) for efficient, durable and highly selective CO₂ reduction to HCOOH. The Sn-QDs were confirmed with high crystallinity and an average size of only 2-3 nm. Small particle size endowed the electrocatalyst with improved electrochemical active surface area (ECSA), which was about 4.4 times of that of Sn particle. This enlarged ECSA as well as accelerated CO₂RR kinetics favored the electrochemical conversion of CO₂. The Faradaic efficiency of HCOOH (FE_HCOOH) on Sn-QDs/CN reached up to 95% at -1.0 V (vs RHE), which exceeded 83% in the recorded wide potential window of 0.5 V. Moreover, the Sn-QDs electrocatalyst exhibited good electrochemical durability for 24 h.

Electrochemical reduction of the greenhouse gas CO₂ in solid oxide electrolysis cells (SOECs) has attracted much attention due to their high energy conversion efficiency and great potential for carbon cycling. Compared with the asymmetrical configuration, symmetrical SOECs with the same material as anode and cathode, can greatly simplify the fabrication process and reduce the complication associated with varied interfaces. Perovskite oxides La_xSr_2-xFe_1.5Ni_0.1Mo_0.4O_6-δ (L_xSFNM, x=0.1, 0.2, 0.3 and 0.4) are prepared and evaluated as symmetrical electrodes in solid oxide electrolysis cells for electrochemical reduction of pure CO₂. The polarization resistances are 0.07 Ω∙cm² in air and 0.62 Ω∙cm² in 50% CO-50% CO₂ for L_0.3SFNM electrode at 800 ℃. An electrolysis current density of 1.17 A∙cm^-2 under 800 ℃ at 1.5 V is achieved for the symmetrical SOECs in pure CO₂. Furthermore, the symmetrical cell demonstrates excellent stability during the preliminary 50 h CO₂ electrolysis measurements.

In recent years, with the consumption of fossil resources and the large amount of CO₂ emissions, the energy crisis and the greenhouse question become deeply serious. The direct synthesis of olefins by CO₂ hydrogenation with iron-based catalysts is one of the best ways to achieve CO₂ reduction. In this study, zirconia (ZrO₂)-supported iron-cobalt catalyst (Fe-Co/ZrO₂) and ZrO₂-supported iron-cobalt-potassium catalyst (Fe-Co-K/ZrO₂) were prepared by impregnation method, which were used for CO₂ hydrogenation to light olefins (C₂⁼-C₄⁼), and the effect of K on the catalytic activity were investigated emphatically. At the condition of 300 ℃ and 1.5 MPa, the activity test show that addition of K increases the CO₂ conversion from 40.8% to 44.8%, improves the selectivity of light olefins from 0.23% to 68.5%, and raises the stability of catalytic performance. The characterization results show that introduction of K improves electron cloud density of the iron species, enhances adsorption strength of the Fe to CO₂, promotes the formation of iron carbide, and facilitates direct dissociation of CO₂ after adsorption on Fe species, thus boosts the performance of CO₂ hydrogenation to light olefins.

The reduction of carbon dioxide (CO₂) to syngas (a mixture of CO and H₂) can not only realize the carbon cycle and decrease the greenhouse effect but also alleviate the energy crisis. Design of catalyst is the key to realize CO₂ resource utilization. Herein, CuO and CuO/ZnO composite were prepared by metal ion co-precipitation method, and their performance of electrochemical CO₂ reduction to syngas under different potentials was investigated by adjusting the catalyst components. The results show that the introduction of zinc (Zn) species can decrease the adsorption intensity of intermediate CO₂^•- on the catalyst, which leads to the decrease of Faraday efficiency (FE) of CO and the increase of FE of H₂, thus achieving controllable regulation of CO/H₂ in the range of 1/1-1/4 under different applied electrochemical potential. In particular, the total FE of syngas CO/H₂ is up to 84% when the ratio of Cu to Zn in the precursor solution is 1 : 2.

The synergy of plasma and catalytic materials for CO₂ methanation provides the possibility for CO₂ reuse. The preparation method of catalytic materials plays an important role on their structure and performance. In this work, Ru/γ-Al₂O₃-P and Ru/γ-Al₂O₃-T catalytic materials were prepared by atmospheric-pressure H₂ plasma reduction and H₂ thermal reduction, respectively, using Ru/γ-Al₂O₃ precursor prepared by incipient wetness impregnation. The catalytic activity of Ru/γ-Al₂O₃ prepared by different methods was evaluated during atmospheric-pressure plasma reduction for CO₂ methanation reaction. Different techniques were used to investigate the effect of preparation methods on the structure of Ru/γ-Al₂O₃, analyze the influences of structural factor on the catalytic activity of Ru/γ-Al₂O₃, and discuss the preparation mechanism of Ru/γ-Al₂O₃-P and Ru/γ-Al₂O₃-T. The results show that the CO₂ conversion of γ-Al₂O₃ support is 24.8% under the combination of atmospheric-pressure plasma, and the main product is CO. However, the main CO₂ catalytic product of Ru/γ-Al₂O₃ is methane under the combination of atmospheric-pressure plasma. CO₂ conversion over Ru/γ-Al₂O₃-P is 77.3%, which is higher than that over Ru/γ-Al₂O₃-T (69.9%). Higher catalytic activity of Ru/γ-Al₂O₃-P is ascribed to the higher metallic Ru ratio and Ru/Al atomic ratio, as well as the smaller and higher dispersion of Ru nanoparticles. This work proves that highly active supported metal catalytic materials can be prepared by atmospheric-pressure H₂ plasma.