查看更多>>摘要：Most studies on electrochemical CO(2 )reduction reaction use pure CO2, which requires extra energy for CO2 capture and enrichment from atmosphere. Herein, nanoconfined ionic liquids are introduced into porous atomically dispersed nickel-nitrogen-carbon (Ni-N-C) catalysts to enrich local CO2 concentration and increase the CO2RR kinetics. A series of high-CO2-solubility ionic liquids (ILs) were impregnated into the pores of the columnar Ni-N-C catalyst to alter the CO2-Ni sites interactions and create a solid/liquid interface with high CO2 concentration. The optimal Ni-N-C/[Bmim][PF6] composite outperforms the Ni-N-C catalyst for pure CO2 electroreduction with a maximum FECO of 99.6% and 2.7-fold larger j(CO). The high solubility of CO2 in ILs compared to aqueous electrolyte enables direct electrolysis of CO2 at low concentrations. When fed with 5-10% (v/v) CO2, the Ni-N-C/[Bmim][PF6] composite exhibited up to 1.5-fold higher FECO and a 68% increase of j(CO), in comparison to Ni-N-C, and robust stability over 30 h.
Sini, M. F.Cutrufello, M. G.Caballero, A.Colon, G....
10页
查看更多>>摘要：In this study, the promoting effect of rhenium addition as a co-dopant on Mo/ZSM-5 catalysts system has been analysed. Hence, bimetallic (Re-Mo/ZSM-5) catalysts have been synthesized using a sequential impregnation methodology. The catalytic performance for direct aromatization of methane reaction has been determined and correlated with their physical and chemical state combining multiple characterization techniques. An important synergy between Mo and Re, affected by the sequential impregnation, has been observed. Thus, Re1-Mo4/ZSM-5 in which Re has been incorporated first shows notably higher aromatic yields and stability against deactivation. Characterization results suggest that catalytic enhancement is due to the important effect of Re presence in close interaction with Mo. Improved evolution of ethane through C-C coupling would be correlated to this catalytic performance. As we discuss, Mo nature and location in the bimetallic systems are strongly conditioned by Re and the impregnation sequence and favours such intermediate step.
查看更多>>摘要：Porous single-crystalline SrTaO2N, combining structural homogeneity and high porosity, afford a great promise as an active photocatalyst. The lack of grain boundaries in SrTaO2N porous single crystals (PSCs) enables fast photocarrier migration from bulk to the surface whilst the high porosity offers adequate accessible surface to perform photocatalytic reactions. In this work, we demonstrate a facile synthesis of SrTaO2N PSCs via a top-otactic conversion route. These SrTaO2N PSCs deliver exceptional activity and stability for photocatalytic O-2 production from water with a record-breaking apparent quantum efficiency as high as 17.9% at 420 +/- 20 nm. Overall water splitting with H-2/O-2 equals 2 has also been attained in a Z-scheme system employing SrTaO2N PSCs as the O-2-evolution moiety. These results signify a paradigm to improve photocatalytic performance based on PSCs, which extends the toolbox to achieve efficient solar water splitting over conventional photocatalysts.
查看更多>>摘要：Rationally design and exploration of bifunctional electrocatalysts with excellent performance towards water splitting is significant for hydrogen energy economy. Herein, a novel Au/Ni3S2 heterostructure catalyst that was composed of self-supported Ni3S2 nanosheets decorated with Au nanoparticles on Ni foam was fabricated. The bifunctional catalyst exhibited excellent catalytic activities towards oxygen evolution reaction (230 mV @ 10 mA cm(-2)) and hydrogen evolution reaction (97 mV @ 10 mA cm(-2)) in 1 M KOH. The electrolytic tank using the bifunctional catalyst only required 1.52 V to deliver 10 mA cm(-2) and sustained for 60 h, outperforming most of advanced bifunctional catalysts. The X-ray absorption fine structure (XAFS) and density functional theory (DFT) calculations validated that the strong electronic coupling at the interface could modulate the electronic structure of Ni3S2, thereby optimizing the free energies of the adsorbed intermediates. This work provides an atomic-scale insight into the structure-properties relation of a promising heterostructure catalyst for water splitting.
查看更多>>摘要：Oxygen-containing groups (OCGs) modified carbon materials can affect the microstructure and chemical composition, which is important for oxygen reduction to hydrogen peroxide (ORHP). Thus, exploring the relationship between structure and activity of OCG-containing electrodes is of great significance. In this work, we synthesized OCGs modified pyrene-based organic molecules as electrocatalysts for ORHP. Their electrocatalytic performance are correlated with types and locations of the modified OCGs. Particularly, the Pyr-2OMe with better absorption of O-2 exhibits high H2O2 selectivity. DFT calculations reveal that the carbon atoms attached OCGs are the catalytic active sites. More importantly, the groups on one side of the molecules (Pyr-2OMe, Pyr2OH, and Pyr-2CO) with large dipole moments exhibit superior catalytic activity. Thus, for the first time we find that the asymmetrically local charge redistribution of these catalysts can promote ORHP process. This work paves an alternative way to supply constructive information for understanding the structure and selectivity correlations.
查看更多>>摘要：The determination of reaction mechanism for electrocatalytic CO2 reduction by experiments is still out of reach on copper catalyst, which limits its advance towards industrial implementation. Here, the Cu/CeO2 catalyst as paradigm was studied to validate the reaction intermediates and pathway. The Cu/CeO2 catalysts with different morphologies were synthesized, and it is discovered that the nanorod Cu/CeO2 catalyst exhibits high selectivity for CO2-to-CH4 with the highest turnover frequency for CH4 production among the samples. Detailed study indicates that the nanorod Cu/CeO2 possesses the largest electrochemically active surface area, higher proportion of O-vacancy sites, and better capability of CO2 adsorption and activation. The chemical nature above together contributes to its high activity. Theoretical calculations reveal that the doping of Cu into CeO2 can significantly lower the reaction energy barrier of *CO2 ->*COOH and change the reaction pathway from *CHOH ->*CH2OH to *CHOH ->*CH, effectively improving the catalytic performance for CO2 electroreduction.
查看更多>>摘要：Photoelectrochemical (PEC) water splitting is one of the most promising strategies to turn solar energy into chemical fuels. The low efficiency of photo-generated charge separation caused by fast electron-hole recombination is regarded as a challenge that hinders the further improvement of TiO2 photoanode performance in PEC cells. Here, the nitrogen-doped carbon dots (N-CDs) anchored TiO2 photoanodes were fabricated by one-step hydrothermal method. The in-situ transient photovoltage (TPV) technology shows that electron-trap effect is formed in TiO2 photoanode due to the existence of N-CDs. Meanwhile, the enhancement of photo-generated charge separation efficiency was proven as the charge extraction of TiO2 is promoted by similar to 160% after anchoring N-CDs. Besides, N-CDs increase the conductivity of TiO2 photoanode and promote the efficiency of photo-generated charge transfer. In addition, the impedance of TiO2 photoanode and its interface are reduced by similar to 34% and similar to 66%, respectively. Under AM 1.5G light intensity and 1.23 V vs. RHE, the highest photocurrent densities of TiO2/N-CDs (TNCD-15 mg) is 3.09 mA cm(-2) in 1.0 M NaOH, which is similar to 3.22 times as high as that of the primitive TiO2. This work explains the mechanism of anchoring N-CDs to improve PEC performance through in-situ characterization, which provides a new idea for PEC material design to achieve higher PEC performances.
NSTL
Elsevier