scholarly journals Dynamic Structural Changes in Nickel Single-Atom Catalysts During Electrochemical Reduction of CO2 to CO

2021 ◽  
Author(s):  
Bingbao Mei ◽  
Changzhi Ai ◽  
Lushan Ma ◽  
Cong Liu ◽  
Shuai Yang ◽  
...  
Keyword(s):  
Active Sites ◽  
Structural Changes ◽  
Theoretical Calculations ◽  
Reduction Reaction ◽  
Single Atom ◽  
Structure Evolution ◽  
Potential Range ◽  
Dynamic Configuration ◽  
Carbon Abatement ◽  
Reduction Of Co2

Abstract Electrochemical CO2 reduction reaction (ECO2RR) is an important route for global carbon abatement. However, a comprehensive picture of the structure evolution of metal active sites is currently lacked in ECO2RR. Here, we present the first full view of Ni single-atom catalyst for ECO2RR over a broad potential range. Comprehensive X-ray absorption spectroscopy (XAS) analyses confirmed the Ni coordinated with pyrrole nitrogen in the form of Ni-N4 attached with an axial O2 ligand. Operando XAS revealed the precise structure of the Ni single-atom catalyst that dynamically changes with the shift of applied potentials. Such changes ultimately contributed to the CO selectivity variation ranging from 20%-99%. Interestingly, the Ni center was found to move toward the N4 plane during the ECO2RR, which played a crucial role of reaching near-unity CO selectivity. Together with theoretical calculations, a clear quantitative correlation between the dynamic configuration and the catalytic properties was established.

scholarly journals Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanming Cai ◽  
Jiaju Fu ◽  
Yang Zhou ◽  
Yu-Chung Chang ◽  
Qianhao Min ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Active Sites ◽  
Theoretical Calculations ◽  
High Energy ◽  
Single Atom ◽  
Faradaic Efficiency ◽  
High Energy Barrier ◽  
Catalytic Sites ◽  
Electron Reduction ◽  
First Time

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 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 CuN2O2 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 CO2 to CH4 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 CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

scholarly journals Efficient electrocatalytic nitrogen reduction to ammonia with aqueous silver nanodots

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Wenyi Li ◽  
Ke Li ◽  
Yixing Ye ◽  
Shengbo Zhang ◽  
Yanyan Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
Theoretical Calculations ◽  
Current Collector ◽  
Electrochemical Reactor ◽  
Reduction Reaction ◽  
Solution Ph ◽  
Faradaic Efficiency ◽  
Yield Rate ◽  
Silver Nanodots ◽  
Ti Mesh

AbstractThe electrocatalytic nitrogen (N2) reduction reaction (NRR) relies on the development of highly efficient electrocatalysts and electrocatalysis systems. Herein, we report a non-loading electrocatalysis system, where the electrocatalysts are dispersed in aqueous solution rather than loading them on electrode substrates. The system consists of aqueous Ag nanodots (AgNDs) as the catalyst and metallic titanium (Ti) mesh as the current collector for electrocatalytic NRR. The as-synthesized AgNDs, homogeneously dispersed in 0.1 M Na2SO4 solution (pH = 10.5), can achieve an NH3 yield rate of 600.4 ± 23.0 μg h−1 mgAg−1 with a faradaic efficiency (FE) of 10.1 ± 0.7% at −0.25 V (vs. RHE). The FE can be further improved to be 20.1 ± 0.9% at the same potential by using Ti mesh modified with oxygen vacancy-rich TiO2 nanosheets as the current collector. Utilizing the aqueous AgNDs catalyst, a Ti plate based two-electrode configured flow-type electrochemical reactor was developed to achieve an NH3 yield rate of 804.5 ± 30.6 μg h−1 mgAg−1 with a FE of 8.2 ± 0.5% at a voltage of −1.8 V. The designed non-loading electrocatalysis system takes full advantage of the AgNDs’ active sites for N2 adsorption and activation, following an alternative hydrogenation mechanism revealed by theoretical calculations.

Atomic regulation of metal-organic framework derived carbon-based single-atom catalysts for electrochemical CO2 reduction reaction

2021 ◽  
Author(s):  
Danni Zhou ◽  
Xinyuan Li ◽  
Huishan Shang ◽  
Fengjuan Qin ◽  
Wenxing Chen
Keyword(s):  
Active Sites ◽  
Metal Organic Framework ◽  
Co2 Reduction ◽  
Carbon Dioxide Reduction ◽  
Reduction Reaction ◽  
Single Atom ◽  
Electrochemical Co2 Reduction ◽  
Metal Organic ◽  
Co2 Reduction Reaction ◽  
Organic Framework

Metal-organic framework (MOF) derived single-atom catalysts (SACs), featured unique active sites and adjustable topological structures, exhibit high electrocatalytic performance on carbon dioxide reduction reactions (CO2RR). By modulating elements and atomic...

scholarly journals Platinum–copper single atom alloy catalysts with high performance towards glycerol hydrogenolysis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xi Zhang ◽  
Guoqing Cui ◽  
Haisong Feng ◽  
Lifang Chen ◽  
Hui Wang ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Value Added ◽  
Catalytic Performance ◽  
Single Atom ◽  
Glycerol Hydrogenolysis ◽  
Single Atom Alloy

AbstractSelective hydrogenolysis of biomass-derived glycerol to propanediol is an important reaction to produce high value-added chemicals but remains a big challenge. Herein we report a PtCu single atom alloy (SAA) catalyst with single Pt atom dispersed on Cu nanoclusters, which exhibits dramatically boosted catalytic performance (yield: 98.8%) towards glycerol hydrogenolysis to 1,2-propanediol. Remarkably, the turnover frequency reaches up to 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1, which is to our knowledge the largest value among reported heterogeneous metal catalysts. Both in situ experimental studies and theoretical calculations verify interface sites of PtCu–SAA serve as intrinsic active sites, in which the single Pt atom facilitates the breakage of central C–H bond whilst the terminal C–O bond undergoes dissociation adsorption on adjacent Cu atom. This interfacial synergistic catalysis based on PtCu–SAA changes the reaction pathway with a decreased activation energy, which can be extended to other noble metal alloy systems.

Highly Efficient Low-Pt-Based Electrocatalysts with Pt Single-Atom Active Sites for Oxygen Reduction Reaction

2020 ◽  
Vol MA2020-01 (38) ◽  
pp. 1688-1688
Author(s):  
Jing Liu ◽  
JeongHan Roh ◽  
DongHoon Song ◽  
Junu Bak ◽  
Hyo-Jong Kim ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Active Sites ◽  
Reduction Reaction ◽  
Single Atom ◽  
Highly Efficient

scholarly journals Migration-Prevention Strategy to Fabricate Single-Atom Fe Implanted N-Doped Porous Carbons for Efficient Oxygen Reduction

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Dong-Li Meng ◽  
Chun-Hui Chen ◽  
Jun-Dong Yi ◽  
Qiao Wu ◽  
Jun Liang ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Carbonaceous Material ◽  
Nitrogen Sources ◽  
Reduction Reaction ◽  
Prevention Strategy ◽  
Alkaline Media ◽  
Single Atom ◽  
Porous Carbons ◽  
Iron Species

It is highly desired but challenging to achieve highly active single-atom Fe sites from iron-based metal-organic frameworks (MOFs) for efficient oxygen reduction reaction (ORR) due to the easy aggregation of iron species and formation of the inactive Fe-based particles during pyrolysis. Herein, a facile migration-prevention strategy is developed involving the incorporation of polyaniline (PANI) into the pores of iron porphyrinic-based MOF PCN-224(Fe) and followed by pyrolysis to obtain the single-atom Fe implanted N-doped porous carbons material PANI@PCN-224(Fe)-900. The introduced PANI inside the pores of PCN-224(Fe) not only served as protective fences to prevent the aggregation of the iron species during thermal annealing, but also acted as nitrogen sources to increase the nitrogen content and form Fe-Nx-C active sites. Compared with the pristine PCN-224(Fe) derived carbonization sample containing Fe-based particles, the carbonaceous material PANI@PCN-224(Fe)-900 without inactive Fe-based particles exhibited superb ORR electrocatalytic activity with a more positive half-wave potential, significantly improved stability in both alkaline media, and more challenging acidic condition. The migration-prevention strategy provides a new way to fabricate atomically dispersed metal active sites via pyrolysis approach for promoting catalysis.

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 Recent Advances in Single-Atom Electrocatalysts for Oxygen Reduction Reaction

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-51 ◽  
Author(s):  
Junxing Han ◽  
Juanjuan Bian ◽  
Chunwen Sun
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Noble Metal ◽  
Active Sites ◽  
Reduction Reaction ◽  
Metal Catalysts ◽  
Single Atom ◽  
Noble Metal Catalysts ◽  
Recent Advances ◽  
Platinum Group

Oxygen reduction reaction (ORR) plays significant roles in electrochemical energy storage and conversion systems as well as clean synthesis of fine chemicals. However, the ORR process shows sluggish kinetics and requires platinum-group noble metal catalysts to accelerate the reaction. The high cost, rare reservation, and unsatisfied durability significantly impede large-scale commercialization of platinum-based catalysts. Single-atom electrocatalysts (SAECs) featuring with well-defined structure, high intrinsic activity, and maximum atom efficiency have emerged as a novel field in electrocatalytic science since it is promising to substitute expensive platinum-group noble metal catalysts. However, finely fabricating SAECs with uniform and highly dense active sites, fully maximizing the utilization efficiency of active sites, and maintaining the atomically isolated sites as single-atom centers under harsh electrocatalytic conditions remain urgent challenges. In this review, we summarized recent advances of SAECs in synthesis, characterization, oxygen reduction reaction (ORR) performance, and applications in ORR-related H2O2 production, metal-air batteries, and low-temperature fuel cells. Relevant progress on tailoring the coordination structure of isolated metal centers by doping other metals or ligands, enriching the concentration of single-atom sites by increasing metal loadings, and engineering the porosity and electronic structure of the support by optimizing the mass and electron transport are also reviewed. Moreover, general strategies to synthesize SAECs with high metal loadings on practical scale are highlighted, the deep learning algorithm for rational design of SAECs is introduced, and theoretical understanding of active-site structures of SAECs is discussed as well. Perspectives on future directions and remaining challenges of SAECs are presented.

A generalized amino-modification strategy to boost CO2 electroreduction current density of single-atom catalysts to industrial application level

2020 ◽  
Author(s):  
Zhipeng Chen ◽  
Xinxin Zhang ◽  
Wei Liu ◽  
Mingyang Jiao ◽  
Kaiwen Mou ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Current Density ◽  
Reduction Reaction ◽  
Single Atom ◽  
Potential Range ◽  
Carbon Supports ◽  
Co2 Electroreduction ◽  
Operating Potential ◽  
Ingenious Method ◽  
Industrial Level

Abstract Although Faraday efficiency (FE) for CO production of single-atom catalysts immobilized on nitrogen-doped carbon supports (M-N/C) for CO2 electrocatalytic reduction reaction (CO2RR) is generally over 90%, M-N/C catalysts demonstrate a poor reaction current density, much worse than the current density of industrial level. Herein, we first report a generalized strategy of amino-functionalized carbon supports to regulate electronic structure of M-N/C catalysts (M=Ni, Fe, Zn) to significantly increase current density of CO production. The aminated Ni single-atom catalyst achieves a remarkable CO partial current density of 447.6 mA cm-2 (a total current density over 500 mA cm-2) with a nearly 90% CO FE at a moderate overpotential of 0.89 V, and especially CO FE can be maintained over 85% in a wide operating potential range from -0.5 V to -1.0 V. DFT calculations and experimental researches demonstrate that the superior activity is attributed to enhanced adsorption energies of CO2* and COOH* intermediates caused by the change of electronic structure of aminated catalysts. This work provides an ingenious method for significantly increasing current density at industrial-relevant level of single-atom catalysts for CO2RR.

scholarly journals Directing reaction pathways via in situ control of active site geometries in PdAu single-atom alloy catalysts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mengyao Ouyang ◽  
Konstantinos G. Papanikolaou ◽  
Alexey Boubnov ◽  
Adam S. Hoffman ◽  
Georgios Giannakakis ◽  
...  
Keyword(s):  
Active Site ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Bimetallic Catalyst ◽  
Theoretical Calculations ◽  
Atomic Scale ◽  
Single Atom ◽  
In Situ Control ◽  
Single Atom Alloy

AbstractThe atomic scale structure of the active sites in heterogeneous catalysts is central to their reactivity and selectivity. Therefore, understanding active site stability and evolution under different reaction conditions is key to the design of efficient and robust catalysts. Herein we describe theoretical calculations which predict that carbon monoxide can be used to stabilize different active site geometries in bimetallic alloys and then demonstrate experimentally that the same PdAu bimetallic catalyst can be transitioned between a single-atom alloy and a Pd cluster phase. Each state of the catalyst exhibits distinct selectivity for the dehydrogenation of ethanol reaction with the single-atom alloy phase exhibiting high selectivity to acetaldehyde and hydrogen versus a range of products from Pd clusters. First-principles based Monte Carlo calculations explain the origin of this active site ensemble size tuning effect, and this work serves as a demonstration of what should be a general phenomenon that enables in situ control over catalyst selectivity.

Sign in / Sign up

Export Citation Format

Share Document