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CO2 mineralized all-solid waste alkali-activated cementitious materials can not only realize the storage of CO2 mineralized, but also shorten the curing cycle of alkali-activated cementitious materials and improve their compressive strength. It is a promising way of CO2 capture and utilization. The effects of the ratio of alkali-activated cementitious materials, mineralized curing pressure and mineralized curing time on the carbon fixation rate and compressive strength of CO2 mineralized cementitious materials were studied. The results show that the calcium carbide slag as alkali activator is more suitable for mineralization curing, and the sample with the highest Ca/Si ratio has the best carbon fixation ability under the same curing condition. Increasing the curing pressure and curing time of CO2 can improve the properties of the samples. Physical and chemical characterization test results show that, the microstructure of the mineralized samples is more compact than that of the natural curing samples, and the calcite-type calcium carbonate produced in the curing process is helpful to increase the compressive strength of the material. The research results provide basic data and reference for the development of CO2 mineralization curing technology of all-solid waste alkali-activated cementitious materials.

Electrochemical CO2 reduction (ECR) to value-added products is regarded as a sustainable strategy to mitigate global warming and energy crisis, and designing highly efficient and robust catalysts is essential. In this work, transition metal sulfides (TMS)-decorated CuS microflower-like structures were prepared via the one-pot hydrothermal synthesis method for ECR to CO, and the influence of TMS doping on ECR performance was demonstrated. Characterization of the catalysts was performed using XRD, FESEM-EDS, N2 physisorption, and XPS, revealing the successful loading of TMS, the formation of microflower-like architectures and the generation of sulfur vacancies. Electrochemical tests demonstrated that doping ZnS, Bi2S3, CdS and MoS2 improved the intrinsic CO2 reduction activity of the CuS catalyst. Particularly, the MoS2-CuS composite catalyst with imperfect petal-like structure showed uniform distribution of edge Mo sites, which worked synergistically with the formed grain boundaries (GBs) and undercoordinated S vacancy sites in promoting CO2 activation, stabilizing *COOH adsorption, facilitating *CO desorption, and lowering the energy barrier of the potential-limiting step for improved CO selectivity. The MoS2-CuS catalyst achieved a maximum CO selectivity of 83.2% at –0.6 V versus the reversible hydrogen electrode (RHE) and a high CO cathodic energetic efficiency of 100%. At this potential, the catalyst maintained stable catalytic activity and CO selectivity during a 333-min electrolysis process. The findings will offer a promising avenue for the development of efficient and stable catalysts for CO production from ECR. [ABSTRACT FROM AUTHOR]

Coal-fired power plant is a major contributor to greenhouse gas emissions. The post-combustion capture is a promising method for CO2 emission reduction but the high thermal demand is unbearable. To address this issue, solar thermal energy and CO2 capture are jointly integrated into the coal-fired power plant in this study. The solar thermal energy is employed to meet the heat requirement of the CO2 capture process, thereby avoiding the electricity loss caused by self-driven CO2 capture. Furthermore, the heat released from the carbonation reaction of MgO adsorbent is integrated into the steam Rankine cycle. By partially substituting the extracted steam for feedwater heating, the electricity output of the power plant is further increased. According to the results from the developed model, the system could achieve a CO2 capture rate of 86.5% and an electricity output enhancement of 9.8% compared to the reference system, which consists of a self-driven CO2 capture coal-fired power plant and PV generation unit. The operational strategy is also optimized and the amount of CO2 emission reduction on a typical day is increased by 11.06%. This work shows a way to combine fossil fuels and renewable energy for low carbon emissions and efficient power generation. [ABSTRACT FROM AUTHOR]