scholarly journals Atomically Dispersed Fe-Co Bimetallic Catalysts for the Promoted Electroreduction of Carbon Dioxide

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Zhangsen Chen ◽  
Gaixia Zhang ◽  
Yuren Wen ◽  
Ning Chen ◽  
Weifeng Chen ◽  
...  
Keyword(s):  
Bimetallic Catalysts ◽  
Active Sites ◽  
High Performance ◽  
High Selectivity ◽  
Bimetallic Catalyst ◽  
Hydrogen Electrode ◽  
Zeolitic Imidazolate Framework ◽  
Faradaic Efficiency ◽  
Dispersed Catalysts ◽  
Wide Potential

AbstractThe electroreduction reaction of CO2 (ECO2RR) requires high-performance catalysts to convert CO2 into useful chemicals. Transition metal-based atomically dispersed catalysts are promising for the high selectivity and activity in ECO2RR. This work presents a series of atomically dispersed Co, Fe bimetallic catalysts by carbonizing the Fe-introduced Co-zeolitic-imidazolate-framework (C–Fe–Co–ZIF) for the syngas generation from ECO2RR. The synergistic effect of the bimetallic catalyst promotes CO production. Compared to the pure C–Co–ZIF, C–Fe–Co–ZIF facilitates CO production with a CO Faradaic efficiency (FE) boost of 10%, with optimal FECO of 51.9%, FEH2 of 42.4% at − 0.55 V, and CO current density of 8.0 mA cm−2 at − 0.7 V versus reversible hydrogen electrode (RHE). The H2/CO ratio is tunable from 0.8 to 4.2 in a wide potential window of − 0.35 to − 0.8 V versus RHE. The total FECO+H2 maintains as high as 93% over 10 h. The proper adding amount of Fe could increase the number of active sites and create mild distortions for the nanoscopic environments of Co and Fe, which is essential for the enhancement of the CO production in ECO2RR. The positive impacts of Cu–Co and Ni–Co bimetallic catalysts demonstrate the versatility and potential application of the bimetallic strategy for ECO2RR.

Au aerogel for selective CO2 electroreduction to CO: ultrafast preparation with high performance

2021 ◽  
Author(s):  
Shenglin Yan ◽  
Samah Awadh Mahyoub ◽  
Jing Lin ◽  
Chunxiao Zhang ◽  
Qing Hu ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Gelation Time ◽  
Active Surface ◽  
Active Surface Area ◽  
Hydrogen Electrode ◽  
Faradaic Efficiency ◽  
External Force Field ◽  
Co2 Electroreduction ◽  
Turbulence Mixing

Abstract Noble metal aerogels (NMAs) have been used in a variety of (photo-)electrocatalytic reactions, but pure Au aerogels (AG) have not been used in CO2 electroreduction to date. To explore the potential application in this direction, AG was prepared to be used as the cathode in CO2 electroreduction to CO. However, the gelation time of NMAs is usually very long, up to several weeks. Here, an excess NaBH4 and turbulence mixing-promoted gelation approach was developed by introducing magnetic stirring as an external force field, which therefore greatly shortened the formation time of Au gels to several seconds. The AG-3 (AG with Au loading of 0.003 g) exhibited a high CO Faradaic efficiency (FE) of 95.6% at an extremely low overpotential of 0.39 V, and over 91% of CO FE was reached in a wide window of -0.4 ~ -0.7 V vs. the reversible hydrogen electrode (RHE). Partial current density in CO was measured to be -19.35 mA cm-2 at -0.8 V vs. RHE under 1 atm of CO2. The excellent performance should be ascribed to its porous structure, abundant active sites, and large electrochemical active surface area. It provides a new method for preparation of AG with ultrafast gelation time and large production at room temperature, and the resulting pure AG was for the first time used in the field of CO2 electroreduction.

scholarly journals Porous Carbon Architecture Assembled by Cross-Linked Carbon Leaves with Implanted Atomic Cobalt for High-Performance Li–S Batteries

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Ruirui Wang ◽  
Renbing Wu ◽  
Chaofan Ding ◽  
Ziliang Chen ◽  
Hongbin Xu ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Specific Capacity ◽  
Three Dimension ◽  
Zeolitic Imidazolate Framework ◽  
Shuttle Effect ◽  
Promising Solution ◽  
Fading Rate ◽  
Kinetics Of ◽  
Sulfur Cathodes

AbstractThe practical application of lithium–sulfur batteries is severely hampered by the poor conductivity, polysulfide shuttle effect and sluggish reaction kinetics of sulfur cathodes. Herein, a hierarchically porous three-dimension (3D) carbon architecture assembled by cross-linked carbon leaves with implanted atomic Co–N4 has been delicately developed as an advanced sulfur host through a SiO2-mediated zeolitic imidazolate framework-L (ZIF-L) strategy. The unique 3D architectures not only provide a highly conductive network for fast electron transfer and buffer the volume change upon lithiation–delithiation process but also endow rich interface with full exposure of Co–N4 active sites to boost the lithium polysulfides adsorption and conversion. Owing to the accelerated kinetics and suppressed shuttle effect, the as-prepared sulfur cathode exhibits a superior electrochemical performance with a high reversible specific capacity of 695 mAh g−1 at 5 C and a low capacity fading rate of 0.053% per cycle over 500 cycles at 1 C. This work may provide a promising solution for the design of an advanced sulfur-based cathode toward high-performance Li–S batteries.

Core-shell Cu@C@ZIF-8 composite: a high-performance electrode material for electrochemical sensing of nitrite with high selectivity and sensitivity

2021 ◽  
Author(s):  
Feng Gao ◽  
Xiaolong Tu ◽  
Yongfang Yu ◽  
Yansha Gao ◽  
Jin Zou ◽  
...  
Keyword(s):  
High Performance ◽  
High Selectivity ◽  
Limit Of Detection ◽  
Metal Organic Framework ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Core Shell ◽  
Zeolitic Imidazolate Framework ◽  
Sensing Platform ◽  
The Difference

Abstract Herein, an efficient electrochemical sensing platform is proposed for selective and sensitive detection of nitrite on the basis of Cu@C@Zeolitic imidazolate framework-8 (Cu@C@ZIF-8) heterostructure. Core-shell Cu@C@ZIF-8 composite was synthesized by pyrolysis of Cu-metal-organic framework@ZIF-8 (Cu-MOF@ZIF-8) in Ar atmosphere on account of the difference of thermal stability between Cu-MOF and ZIF-8. For the sensing system of Cu@C@ZIF-8, ZIF-8 with proper pore size allows nitrite diffuse through the shell, while big molecules cannot, which ensures high selectivity of the sensor. On the other hand, Cu@C as electrocatalyst promotes the oxidation of nitrite, thereby resulting high sensitivity of the sensor. Accordingly, the Cu@C@ZIF-8 based sensor presents excellent performance for nitrite detection, which achieves a wide linear response range of 0.1 µM to 300.0 µM, and a low limit of detection (LOD) of 0.033 µM. In addition, the Cu@C@ZIF-8 sensor possesses excellent stability and reproducibility, and was employed to quantify nitrite in sausage samples with recoveries of 95.45-104.80%.

scholarly journals A Pd/MnO2 Electrocatalyst for Nitrogen Reduction to Ammonia under Ambient Conditions

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 802
Author(s):  
Chang Sun ◽  
Yingxin Mu ◽  
Yuxin Wang
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Pd Nanoparticles ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Hydrogen Electrode ◽  
Faradaic Efficiency ◽  
Transmission Electron ◽  
Alternative Approach ◽  
Supported Pd

Electrochemical ammonia synthesis, which is an alternative approach to the Haber–Bosch process, has attracted the attention of researchers because of its advantages including mild working conditions, environmental protection, and simple process. However, the biggest problem in this field is the lack of high-performance catalysts. Here, we report high-efficiency electroreduction of N2 to NH3 on γ-MnO2-supported Pd nanoparticles (Pd/γ-MnO2) under ambient conditions, which exhibits excellent catalytic activity with an NH3 yield rate of 19.72 μg·mg−1Pd h−1 and a Faradaic efficiency of 8.4% at −0.05 V vs. the reversible hydrogen electrode (RHE). X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization shows that Pd nanoparticles are homogeneously dispersed on the γ-MnO2. Pd/γ-MnO2 outperforms other catalysts including Pd/C and γ-MnO2 because of its synergistic catalytic effect between Pd and Mn.

scholarly journals Photoelectrochemical Reduction of CO2 to Syngas by Reduced Ag Catalysts on Si Photocathodes

2020 ◽  
Vol 10 (10) ◽  
pp. 3487 ◽  
Author(s):  
Changyeon Kim ◽  
Seokhoon Choi ◽  
Min-Ju Choi ◽  
Sol A Lee ◽  
Sang Hyun Ahn ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Co2 Reduction ◽  
Reduction Reaction ◽  
Hydrogen Electrode ◽  
Faradaic Efficiency ◽  
Onset Potential ◽  
Reduction Of Co2 ◽  
Co2 Reduction Reaction ◽  
Ag Catalysts

The photoelectrochemical reduction of CO2 to syngas that is used for many practical applications has been emerging as a promising technique to relieve the increase of CO2 in the atmosphere. Si has been considered to be one of the most promising materials for photoelectrodes, but the integration of electrocatalysts is essential for the photoelectrochemical reduction of CO2 using Si. We report an enhancement of catalytic activity for CO2 reduction reaction by Ag catalysts of tuned morphology, active sites, and electronic structure through reducing anodic treatment. Our proposed photocathode structure, a SiO2 patterned p-Si photocathode with these reduced Ag catalysts, that was fabricated using electron-beam deposition and electrodeposition methods, provides a low onset-potential of −0.16 V vs. the reversible hydrogen electrode (RHE), a large saturated photocurrent density of −9 mA/cm2 at −1.23 V vs. RHE, and faradaic efficiency for CO of 47% at −0.6 V vs. RHE. This photocathode can produce syngas in the ratio from 1:1 to 1:3, which is an appropriate proportion for practical application. This work presents a new approach for designing photocathodes with a balanced catalytic activity and light absorption to improve the photoelectrochemical application for not only CO2 reduction reaction, but also water splitting or N2 reduction reaction.

scholarly journals Zn- and Ti-Doped SnO2 for Enhanced Electroreduction of Carbon Dioxide

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2354
Author(s):  
Katarzyna Bejtka ◽  
Nicolò B. D. Monti ◽  
Adriano Sacco ◽  
Micaela Castellino ◽  
Samuele Porro ◽  
...  
Keyword(s):  
Formic Acid ◽  
Current Density ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Active Surface ◽  
Active Surface Area ◽  
Co2 Conversion ◽  
Hydrogen Electrode ◽  
Faradaic Efficiency ◽  
Wet Impregnation

The electrocatalytic reduction of CO2 into useful fuels, exploiting rationally designed, inexpensive, active, and selective catalysts, produced through easy, quick, and scalable routes, represents a promising approach to face today’s climate challenges and energy crisis. This work presents a facile strategy for the preparation of doped SnO2 as an efficient electrocatalyst for the CO2 reduction reaction to formic acid and carbon monoxide. Zn or Ti doping was introduced into a mesoporous SnO2 matrix via wet impregnation and atomic layer deposition. It was found that doping of SnO2 generates an increased amount of oxygen vacancies, which are believed to contribute to the CO2 conversion efficiency, and among others, Zn wet impregnation resulted the most efficient process, as confirmed by X-ray photoelectron spectroscopy analysis. Electrochemical characterization and active surface area evaluation show an increase of availability of surface active sites. In particular, the introduction of Zn elemental doping results in enhanced performance for formic acid formation, in comparison to un-doped SnO2 and other doped SnO2 catalysts. At −0.99 V versus reversible hydrogen electrode, the total faradaic efficiency for CO2 conversion reaches 80%, while the partial current density is 10.3 mA cm−2. These represent a 10% and a threefold increases for faradaic efficiency and current density, respectively, with respect to the reference un-doped sample. The enhancement of these characteristics relates to the improved charge transfer and conductivity with respect to bare SnO2.

The Importance of Molybdenum(IV) Active Sites in Promoting Electrochemical Reduction of N2 to NH3 with MoFe Bimetallic Catalysts

2021 ◽  
Author(s):  
Kai Li ◽  
Yan Li ◽  
Kun Jiang ◽  
Tao Li ◽  
Yun-Quan Liu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Thermal Processing ◽  
Bimetallic Catalysts ◽  
Active Sites ◽  
Spectroscopy Analysis ◽  
Electronic Interactions ◽  
Faradaic Efficiency ◽  
X Ray ◽  
Pyrolysis Method ◽  
Improved Performance

Abstract To overcome the low faradaic efficiency (FE) of single Mo or Fe based electrocatalysts in nitrogen reduction reactions (NRR) due to the competition from the hydrogen evolution reaction (HER), a series of bimetallic MoFe compound catalysts were prepared under an NH3 atmosphere through a facile precipitation-pyrolysis method. The formed tetravalent Mo was found to be capable of inducing better electronic interactions between the surface nitrogen species and the Fe metal groups, thus improving the FE. It was demonstrated that the prepared ternary MoFe-N catalyst exhibited a remarkable FE of 33.26 % and a high NH3 yield of 33.31 μg h-1 mg-1cat. for NRR, which was believed to have been caused by an obvious change in the valence of Mo that resulted in a lower HER activity. X-ray photoelectron spectroscopy analysis further revealed that thermal processing under an NH3 atmosphere formed the Mo(IV) active sites in Mo-N bond, which led to a significant suppression in HER activity. Finally, through the study of the surface hydrogenation mechanism, it was concluded that the synergistic effect of the adsorbed H* and Mo active sites was the main reason for the improved performance of NRR.

A high-performance Pt–Co bimetallic catalyst with polyethyleneimine decorated graphene oxide as support for hydrolysis of ammonia borane

RSC Advances ◽  
2014 ◽  
Vol 4 (77) ◽  
pp. 41152-41158 ◽  
Author(s):  
Mengxiong Li ◽  
Jiantong Hu ◽  
Zhongxin Chen ◽  
Hongbin Lu
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Bimetallic Catalysts ◽  
High Performance ◽  
Bimetallic Catalyst ◽  
Ammonia Borane ◽  
Hydrolysis Of

PEI–GO/Pt0.17Co0.83was synthesized and showed the best catalytic activity of the reported Pt-based bimetallic catalysts for the hydrolysis of ammonia borane.

scholarly journals Fast operando spectroscopy tracking in situ generation of rich defects in silver nanocrystals for highly selective electrochemical CO2 reduction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinhao Wu ◽  
Yanan Guo ◽  
Zengsen Sun ◽  
Fenghua Xie ◽  
Daqin Guan ◽  
...  
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Co2 Reduction ◽  
Density Functional Theory Calculations ◽  
Defect Concentration ◽  
Hydrogen Electrode ◽  
Efficient Catalyst ◽  
Faradaic Efficiency ◽  
Electrochemical Co2 Reduction ◽  
Cell Reactor

AbstractElectrochemical CO2 reduction (ECR) is highly attractive to curb global warming. The knowledge on the evolution of catalysts and identification of active sites during the reaction is important, but still limited. Here, we report an efficient catalyst (Ag-D) with suitable defect concentration operando formed during ECR within several minutes. Utilizing the powerful fast operando X-ray absorption spectroscopy, the evolving electronic and crystal structures are unraveled under ECR condition. The catalyst exhibits a ~100% faradaic efficiency and negligible performance degradation over a 120-hour test at a moderate overpotential of 0.7 V in an H-cell reactor and a current density of ~180 mA cm−2 at −1.0 V vs. reversible hydrogen electrode in a flow-cell reactor. Density functional theory calculations indicate that the adsorption of intermediate COOH could be enhanced and the free energy of the reaction pathways could be optimized by an appropriate defect concentration, rationalizing the experimental observation.

scholarly journals Evaluation of favorable operating conditions for quinoline hydrodenitrogenation

2018 ◽  
Vol 24 (4) ◽  
pp. 379-386
Author(s):  
Gabriel Vasconcelos ◽  
Hugo Oliveira ◽  
Rita Colman
Keyword(s):  
Nitrogen Removal ◽  
Bimetallic Catalysts ◽  
High Selectivity ◽  
Bimetallic Catalyst ◽  
Simulation Analysis ◽  
Operating Conditions ◽  
Environmental Aspects ◽  
Hydrogen Flow ◽  
Hydrogen Consumption ◽  
Key Factor

Economic and environmental aspects render nitrogen removal from oil loads increasingly more necessary. Studies have proven that it is possible to achieve high selectivity to quinoline hydrodenitrogenation products using PtMo bimetallic catalysts supported on zeolites. However, the reaction follows the route of higher hydrogen consumption. The main products in this reaction are propylcyclohexene, propylbenzene, and propylcyclohexane, being more selective for propylcyclohexane, which is directly related to increased hydrogen consumption. Therefore, the identification of the best conditions of temperature and hydrogen flow to make the process more selective for propylbenzene is of interest. The study conducted in UniSim? Software showed considerable improvements in selectivity with increasing the temperature of reaction between 450 and 500?C. Additionally, the catalytic tests confirmed that the bimetallic catalyst reached higher selectivity when the temperature of 460?C was used, as determined by simulation. The experimental results and the simulation analysis showed that molybdenum in catalysts is essential for HDN reactions and that temperature is a key factor toward propylbenzene selectivity.

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