Abstract
Single-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO
2
reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO ...instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN
2
O
2
sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO
2
to CH
4
with current density of 40 mA·cm
-2
in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN
2
O
2
active sites are due to the proper elevated CH
4
and H
2
energy barrier and fine-tuned electronic structure of Cu active sites.
Tin (Sn) is known to be a good catalyst for electrochemical reduction of CO2 to formate in 0.5 M KHCO3. But when a thin layer of SnO2 is coated over Cu nanoparticles, the reduction becomes ...Sn-thickness dependent: the thicker (1.8 nm) shell shows Sn-like activity to generate formate whereas the thinner (0.8 nm) shell is selective to the formation of CO with the conversion Faradaic efficiency (FE) reaching 93% at −0.7 V (vs reversible hydrogen electrode (RHE)). Theoretical calculations suggest that the 0.8 nm SnO2 shell likely alloys with trace of Cu, causing the SnO2 lattice to be uniaxially compressed and favors the production of CO over formate. The report demonstrates a new strategy to tune NP catalyst selectivity for the electrochemical reduction of CO2 via the tunable core/shell structure.
Monodisperse Cu nanoparticles (NPs) assembled on a pyridinic-N rich graphene (p-NG) support show a Cu NP mass- and size-dependent catalysis for the selective electrochemical reduction of CO2 to ...ethylene (C2H4). For the 7nm Cu NPs assembled on the p-NG with the p-NG/Cu mass ratio of 1:1, the C2H4 formation Faradaic efficiency and hydrocarbon selectivity reach 19% and 79% respectively at −0.9V (vs reversible hydrogen electrode). The p-NG itself can catalyze the CO2 reduction to formate, but in the composite p-NG-Cu structure, the pyridinic-N functions as a CO2 and proton absorber, facilitating hydrogenation and carbon–carbon coupling reactions on Cu for the formation of C2H4. The work demonstrates a new strategy to improve Cu NP catalytic activity and selectivity for the electrochemical reduction of CO2 for sustainable chemistry and energy applications.
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•Monodisperse Cu nanoparticles are synthesized and assembled on pyridinic-N rich graphene (p-NG).•7nm Cu NPs assembled on p-NG are active and selective for electrochemical CO2 reduction to ethylene.•Standalone p-NG shows much higher activity than graphitic-N rich graphene and graphene oxide for CO2 reduction to formate.
Electrochemical reduction of CO2 into value-added products is an effective approach to relieve environmental and energetic issues. Herein, EDTA anion-modified porous hollow copper microspheres (H–Cu ...MPs) were constructed by EDTA-2Na-assisted electrodeposition. The faradic efficiency (FE) of ethylene doubled from 23.3% to 50.1% at −0.82 V vs RHE in nearly neutral 0.1 M KHCO3 solution, one of the highest values among copper-based electrodeposited catalysts. Apart from the favorable influence from morphology regulated by EDTA-2Na, theoretical calculations revealed that the adsorbed EDTA anions were able to create a local charged copper surface to stabilize the transition state and dimer and to assist in the stabilization by interacting with OCCO adsorbate synergistically, which contributed to the outstanding catalytic performance together.
Risk assessment of fault water inrush during deep mining Cao, Zhaodan; Gu, Qixiong; Huang, Zhen ...
International Journal of Mining Science and Technology/International journal of mining science and technology,
March 2022, 2022-03-00, 2022-03-01, Volume:
32, Issue:
2
Journal Article
Peer reviewed
Open access
With the gradual depletion of shallow coal resources, the Yanzhou mine in China will enter the lower coal seam mining phase. However, as mining depth increases, lower coal seam mining in Yanzhou is ...threatened by water inrush in the Benxi Formation limestone and Ordovician limestone. The existing prediction models for the water burst at the bottom of the coal seam are less accurate than expected owing to various controlling factors and their intrinsic links. By analyzing the hydrogeological exploration data of the Baodian lower seam and combining the results of the water inrush coefficient method and the Yanzhou mine pressure seepage test, an evaluation model of the seepage barrier capacity of the fault was established. The evaluation results show the water of the underlying limestone aquifer in the Baodian mine area mainly threatens the lower coal mining through the fault fracture zone. The security of mining above confined aquifer in the Baodian mine area gradually decreases from southwest to northeast. By comparing the water inrush coefficient method and the evaluation model of fault impermeability, the results show the evaluation model based on seepage barrier conditions is closer to the actual situation when analyzing the water breakout situation at the working face.
Developing low-temperature SCR catalysts is crucial for efficiently removing both NO and Hg0. Precisely adjusting the surface structure of Cu–Ce–BTC catalysts under the influence of halogen groups ...enhances their catalytic performance. In this study, we synthesized a series of halogen-modified Cu–Ce–BTC catalysts and investigated their structural characteristics and performance through a combination of calculations, characterization, and experiments. The characterization indicated that the original physicochemical properties remain unchanged after halogen modification, but the presence of C–X (Cl, Br, I) can be observed. During the NH3-SCR reaction, we observed that halogen modification enhances the catalytic activity, with Cl having a notably higher effect than Br and I. Additionally, O2 significantly promotes the removal of both NO and Hg0. Meanwhile NO has a minimal impact on NO and Hg0 removal. Furthermore, NH3 promotes NO removal and inhibits Hg0 removal. However, both SO2 and H2O have an inhibitory effect on the removal of both NO and Hg0, with H2O's effect being more pronounced. DFT verified that the NH3-SCR reaction on Cl–Cu–Ce–BTC follows both E–R and L–H mechanisms, with NH2NO identified as the primary reactant. The oxidation reaction of Hg0 mainly follows the Mars–Maessen mechanism.
For the purpose of broadening the understanding of the sulfonic acid coordination mechanism, a coordination system consisting of Eu(III) ion and 1,3,6,8-pyrene tetra-sulfonate (1,3,6,8-PTS) ligand ...was chosen as the typical research object. By step regulating the volume ratio of mixed solvents and the molar ratio of metal salts to ligands, two pyrene tetra-sulfonate europium coordination polymers, Eu6(μ6-O)(μ3-OH)8(NO3)6(1,3,6,8-H2PTS)(H2O)10 (1) and Eu(NO3)(1,3,6,8-PTS)0.5(H2O)3·0.5bipy (2), were obtained in sequence. Compound 1 shows a 1D chain-like structure interconnected with 1,3,6,8-PTS bridging ligands and rare Eu6(μ6-O)(μ3-OH)8(NO3)62+ cluster nodes, while compound 2 shows a 2D layered structure. Further structural comparison with compound Eu(1,3,6,8-PTS)(H2O)7·4H2O·Hbipy (EuPTSbp-1) was discussed in detail and the structure formation mechanism was analyzed. On this basis, a sequential modulation strategy for pyrene tetra-sulfonate europium coordination polymers was proposed.
After the Industrial Revolution, the ever-increasing atmospheric CO2 concentration has resulted in significant problems for human beings. Nearly all countries in the world are actively taking ...measures to fight for carbon neutrality. In recent years, negative carbon emission technologies have attracted much attention due to their ability to reduce or recycle excess CO2 in the atmosphere. This review summarizes the state-of-the-art negative carbon emission technologies, from the artificial enhancement of natural carbon sink technology to the physical, chemical, or biological methods for carbon capture, as well as CO2 utilization and conversion. Finally, we expound on the challenges and outlook for improving negative carbon emission technology to accelerate the pace of achieving carbon neutrality.
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•State-of-the-art negative carbon emission technologies are reviewed and summarized.•The challenges and prospects of each technology are given.•Since both capture and conversion are relatively energy-consuming, the intelligent design of combined systems can significantly reduce costs and operational steps, which may be the focus of future negative carbon technology development.
Electrocatalytic CO2 reduction technology has been considered a promising approach to alleviate the severe environmental and energy issues caused by the anthropogenic over-emission of CO2. Coupling ...CO2 reduction with nitrogen (N)-pollutants reduction from wastewater to produce higher valued products (e.g., urea, amide, amine, etc.) could significantly extend the application scenarios and product categories of CO2 reduction technologies. This paper investigates the available CO2 and N-pollutants sources and summarizes the recent progress of electrocatalytic C-N coupling reactions. Based on the fundamental research, technical concerns for scale-up applications of C-N coupling electrocatalysis are thoroughly discussed. Finally, we prospect the opportunities and challenges with an in-depth understanding of the underlying dominant factors in applying C-N coupling electrocatalysis. Further development in recycling CO2 and N pollutants via the electrocatalytic C-N coupling process is also discussed.
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Catalysis; Electrochemistry; Engineering
Electrocatalytic CO2 reduction (ECR) to high-value fuels and chemicals offers a promising conversion technology for achieving sustainable carbon cycles. In recent years, although great efforts have ...been made to develop high-efficiency ECR catalysts, challenges remain in achieving high activity and long durability simultaneously. Taking advantage of the adjustable structure, tunable component, and the M–Ch (M = Sn, In, Bi, etc., Ch = S, Se, Te) covalent bonds stabilized metal centers, the p-block metal chalcogenides (PMC) based electrocatalysts have shown great potential in converting CO2 into CO or formates. In addition, the unique p-block electron structure can suppress the competitive hydrogen evolution reaction and enhance the adsorption of ECR intermediates. Seeking to systematically understand the structure–activity relationship of PMC-based ECR catalysts, this review summarizes the recent advances in designing PMC electrocatalysts for CO2 reduction based on the fundamental aspects of heterogeneous ECR process, including advanced strategies for optimizing the intrinsic activity and improving the loading density of catalytic sites, constructing highly stable catalysts, and tuning product selectivities. Subsequently, we outline the challenges and perspectives on developing high-performance PMC ECR catalysts for practical applications.
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•Recent advances in p-block metal chalcogenides (PMC) for electrocatalytic CO2 reduction (ECR) are comprehensively reviewed.•Advanced design strategies for improving ECR performance are discussed.•Challenges and future prospects for PMC-based ECR catalysts are outlined.
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