Mesopore‐Rich Fe–N–C Catalyst with FeN₄–O–NC Single‐Atom Sites Delivers Remarkable Oxygen Reduction Reaction Performance in Alkaline Media

Advanced Materials, Journal Year: 2022, Volume and Issue: 34(29)

Published: May 18, 2022

Fe-N-C catalysts offer excellent performance for the oxygen reduction reaction (ORR) in alkaline media. With a view toward boosting intrinsic ORR activity of Fe single-atom sites catalysts, fine-tuning local coordination to optimize binding energies intermediates is imperative. Herein, porous FeN4 -O-NCR electrocatalyst rich catalytically accessible -O (wherein single atoms are coordinated four in-plane nitrogen and one subsurface axial atom) supported on N-doped carbon nanorods (NCR) reported. K-edge X-ray absorption spectroscopy (XAS) verifies presence active -O-NCR, while density functional theory calculations reveal that offers lower energy more selective 4-electron/4-proton pathway compared traditional sites. Electrochemical tests validate outstanding ORR, outperforming Pt/C almost all other M-N-C reported date. A primary zinc-air battery constructed using delivers peak power 214.2 mW cm-2 at current 334.1 mA , highlighting benefits optimizing iron atoms.

Language: Английский

---

Altering Ligand Fields in Single-Atom Sites through Second-Shell Anion Modulation Boosts the Oxygen Reduction Reaction

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(5), P. 2197 - 2207

Published: Jan. 28, 2022

Single-atom catalysts based on metal-N4 moieties and anchored carbon supports (defined as M-N-C) are promising for oxygen reduction reaction (ORR). Among those, M-N-C with 4d 5d transition metal (TM4d,5d) centers much more durable not susceptible to the undesirable Fenton reaction, especially compared 3d ones. However, ORR activity of these TM4d,5d-N-C is still far from satisfactory; thus far, there few discussions about how accurately tune ligand fields single-atom TM4d,5d sites in order improve their catalytic properties. Herein, we leverage Ru-N-C a model system report an S-anion coordination strategy modulate catalyst's structure performance. The S anions identified bond N atoms second shell Ru centers, which allows us manipulate electronic configuration central sites. S-anion-coordinated catalyst delivers only but also outstanding long-term durability, superior those commercial Pt/C most near-term catalysts. DFT calculations reveal that high attributed lower adsorption energy intermediates at Metal-air batteries using this cathode side exhibit fast kinetics excellent stability.

Language: Английский

---

Triggering Lattice Oxygen Activation of Single‐Atomic Mo Sites Anchored on Ni–Fe Oxyhydroxides Nanoarrays for Electrochemical Water Oxidation

Advanced Materials, Journal Year: 2022, Volume and Issue: 34(29)

Published: May 17, 2022

Tuning the reactivity of lattice oxygen is significance for lowering energy barriers and accelerating evolution reaction (OER). Herein, single-atomic Mo sites are anchored on Ni-Fe oxyhydroxide nanoarrays by a facile metal-organic-framework-derived strategy, exhibiting superior performance toward OER in alkaline media. In situ electrochemical spectroscopy isotope-labeling experiments reveal involvement during cycles. Combining theoretical experimental investigations electronic configuration, it comprehensively confirmed that incorporation enables higher oxidation state metal strengthened metal-oxygen hybridization, as well formation oxidized ligand holes above Fermi level. word, considerable acceleration water achieved via enhancing triggering activation. This work may provide new insights designing ideal electrocatalysts tuning chemical activating anions ligands.

Language: Английский

---

Breaking Local Charge Symmetry of Iron Single Atoms for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(39)

Published: July 22, 2023

The electrochemical conversion of nitrate pollutants into value-added ammonia is a feasible way to achieve artificial nitrogen cycle. However, the development electrocatalytic nitrate-to-ammonia reduction reaction (NO3- RR) has been hampered by high overpotential and low Faradaic efficiency. Here we develop an iron single-atom catalyst coordinated with phosphorus on hollow carbon polyhedron (denoted as Fe-N/P-C) NO3- RR electrocatalyst. Owing tuning effect atoms breaking local charge symmetry single-Fe-atom catalyst, it facilitates adsorption ions enrichment some key intermediates during process. Fe-N/P-C exhibits 90.3 % efficiency yield rate 17980 μg h-1 mgcat-1 , greatly outperforming reported Fe-based catalysts. Furthermore, operando SR-FTIR spectroscopy measurements reveal pathway based observed under different applied potentials durations. Density functional theory calculations demonstrate that optimized free energy ascribed asymmetric atomic interface configuration, which achieves optimal electron density distribution. This work demonstrates critical role atomic-level precision modulation heteroatom doping for RR, providing effective strategy improving catalytic performance single atom catalysts in reactions.

Language: Английский

---

Template-Sacrificing Synthesis of Well-Defined Asymmetrically Coordinated Single-Atom Catalysts for Highly Efficient CO₂ Electrocatalytic Reduction

ACS Nano, Journal Year: 2022, Volume and Issue: 16(2), P. 2110 - 2119

Published: Feb. 11, 2022

Although various single-atom catalysts have been designed, atomically engineering their coordination environment remains a great challenge. Herein, one-pot template-sacrificing pyrolysis approach is developed to synthesize well-defined Ni-N4-O catalytic sites on highly porous graphitic carbon for electrocatalytic CO2 reduction CO with high Faradaic efficiency (maximum of 97.2%) in wide potential window (-0.56 -1.06 V vs RHE) and stability. In-depth experimental theoretical studies reveal that the axial Ni-O introduces asymmetry center, leading lower Gibbs free energy rate-limiting step, strengthened binding *COOH, weaker association *CO. The present results demonstrate successful atomic-level high-surface-area carbon-supported Ni (SACs), demonstrated method can be applied an array SACs (metal-N4-O) catalysis applications.

Language: Английский

---

Boosting CO₂Electroreduction over a Cadmium Single‐Atom Catalyst by Tuning of the Axial Coordination Structure

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(38), P. 20803 - 20810

Published: July 17, 2021

Abstract Guided by first‐principles calculations, it was found that Cd single‐atom catalysts (SACs) have excellent performance in activating CO 2 , and the introduction of axial coordination structure to SACs cannot only further decrease free energy barrier reduction, but also suppress hydrogen evolution reaction (HER). Based on above discovery, we designed synthesized a novel SAC comprises an optimized CdN 4 S 1 moiety incorporated carbon matrix. It shown catalyst exhibited outstanding electroreduction CO. The faradaic efficiency (FE) could reach up 99.7 % with current density 182.2 mA cm −2 H‐type electrolysis cell, turnover frequency (TOF) value achieve 73000 h −1 which much higher than reported date. This work shows successful example how design highly efficient guided theoretical calculations.

Language: Английский

---

Axial chlorine coordinated iron-nitrogen-carbon single-atom catalysts for efficient electrochemical CO2 reduction

Chemical Engineering Journal, Journal Year: 2021, Volume and Issue: 430, P. 132882 - 132882

Published: Oct. 12, 2021

Language: Английский

---

Dual Role of Pyridinic-N Doping in Carbon-Coated Ni Nanoparticles for Highly Efficient Electrochemical CO₂ Reduction to CO over a Wide Potential Range

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(2), P. 1364 - 1374

Published: Jan. 7, 2022

Developing efficient and stable electrocatalysts within a wide potential range is vital for the mature applications of electrocatalytic CO2 reduction reaction (CO2RR) into value-added chemical products. Herein, we engineered NC@Ni/C nano-composite featuring core–shell structure pyridinic-N-rich carbon layer encapsulating Ni nanoparticles (NPs) as highly effective electrocatalyst CO2RR to CO over range. The catalyst demonstrates high Faradaic efficiency (FECO) >90% in from −0.65 −1.45 V [vs reversible hydrogen electrode (RHE)] with maximum FECO 97% at −1.05 (vs RHE). Strikingly, it exhibits an excellent stability constant current density > 95% 92 h Structural studies DFT calculations further reveal that pyridinic-N doping shell NPs plays dual role promoting activity. It not only alleviates mass transfer limitation by enhancing adsorption capacity, but also lowers energy barrier *COOH formation rate-determining step electronic modulation Ni. This work may shed more light on seeking practical catalysts high-efficiency electrochemical broad window.

Language: Английский

---

Insight into the Effect of the d-Orbital Energy of Copper Ions in Metal–Organic Frameworks on the Selectivity of Electroreduction of CO₂ to CH₄

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(5), P. 2749 - 2755

Published: Feb. 11, 2022

It is of great significance to reveal the influence small differences in coordination environments metal ions catalytic active centers on selectivity products electrocatalytic CO2 reduction reaction (CO2RR). Here, two types metal–organic frameworks (MOFs) based square-pyramidal CuO5 and square-planar CuO4 nodes, respectively, are compared regard their performances CO2RR. The MOF (Cu-DBC, H8DBC = dibenzo-[g,p]chrysene-2,3,6,7,10,11,14,15-octaol) constructed by nodes catechol-derived ligands exhibit high performance for CH4 with a Faradaic efficiency 56% current density 11.4 mA cm–2 at −1.4 V vs RHE. In comparison, other MOFs, Cu-HHTP (HHTP 2,3,6,7,10,11-hexahydroxytriphenylene) Cu-THQ (THQ tetrahydroxy-1,4-quinone), ligands, that CO sole reduced product. Theoretical calculations Cu L-edge adsorption spectroscopy revealed energy levels d-orbitals (dz2, dxz, dyz) site elevated those site. As result, sites can strongly adsorb *CO intermediates hence facilitate hydrogenation into *CHO, which beneficial yielding instead CO. This work will be helpful understand mechanism copper-based catalysts hydrocarbons.

Language: Английский

---

Efficient Photoreduction of Diluted CO₂to Tunable Syngas by Ni−Co Dual Sites through d‐band Center Manipulation

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(42)

Published: Aug. 29, 2022

Photocatalytic conversion of CO2 into syngas is a promising way to address the energy and environmental challenges. Here we report integration Ni-Co dual sites on Ni doped Co3 O4 ultrathin nanosheets assembled double-hollow nanotube (Ni-Co3 NSDHN) for efficient photoreduction low-concentration . Quasi in situ spectra density functional theory calculations demonstrate that declining d-band center enables electrons accumulation dxz /dyz -2π* dz2 -5σ orbitals. As result, binding strength *CO weakened *H adsorption site modulated from metal an oxygen site. Remarkably, Ni-Co3 NSDHN exhibits superior diluted photoconversion activity controllable selectivity under irradiation visible light or even natural sunlight. A evolution rate 170.0 mmol g-1 h-1 with apparent quantum yield 3.7 % continuously adjustable CO/H2 ratios 1 : 10 are achieved.

Language: Английский

---