scholarly journals Photocatalytic and Electrocatalytic Properties of Cu-Loaded ZIF-67-Derivatized Bean Sprout-Like Co-TiO2/Ti Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1904
Author(s):  
Hye Ji Jang ◽  
So Jeong Park ◽  
Ju Hyun Yang ◽  
Sung-Min Hong ◽  
Choong Kyun Rhee ◽  
...  
Keyword(s):  
Co2 Reduction ◽  
Hybrid Nanostructures ◽  
Cubic Phase ◽  
Flow Conditions ◽  
Bean Sprout ◽  
Deposition Amount ◽  
Tafel Slopes ◽  
Sputter Deposited ◽  
Electrochemical Water Splitting ◽  
Electrochemical Oxygen

ZIF-derivatized catalysts have shown high potential in catalysis. Herein, bean sprout-like Co-TiO2/Ti nanostructures were first synthesized by thermal treatment at 800 °C under Ar-flow conditions using sacrificial ZIF-67 templated on Ti sheets. It was observed that ZIF-67 on Ti sheets started to thermally decompose at around 350 °C and was converted to the cubic phase Co3O4. The head of the bean sprout structure was observed to be Co3O4, while the stem showed a crystal structure of rutile TiO2 grown from the metallic Ti support. Cu sputter-deposited Co-TiO2/Ti nanostructures were also prepared for photocatalytic and electrocatalytic CO2 reduction performances, as well as electrochemical oxygen reaction (OER). Gas chromatography results after photocatalytic CO2 reduction showed that CH3OH, CO and CH4 were produced as major products with the highest MeOH selectivity of 64% and minor C2 compounds of C2H2, C2H4 and C2H6. For electrocatalytic CO2 reduction, CO, CH4 and C2H4 were meaningfully detected, but H2 was dominantly produced. The amounts were observed to be dependent on the Cu deposition amount. Electrochemical OER performances in 0.1 M KOH electrolyte exhibited onset overpotentials of 330–430 mV (vs. RHE) and Tafel slopes of 117–134 mV/dec that were dependent on Cu-loading thickness. The present unique results provide useful information for synthesis of bean sprout-like Co-TiO2/Ti hybrid nanostructures and their applications to CO2 reduction and electrochemical water splitting in energy and environmental fields.

Electrochemical hydrogen evolution and CO2 reduction over hierarchical MoSxSe2-x hybrid nanostructures

2019 ◽  
Vol 489 ◽  
pp. 976-982 ◽  
Author(s):  
Hye In Lee ◽  
Hwanhee Yu ◽  
Choong Kyun Rhee ◽  
Youngku Sohn
Keyword(s):  
Hydrogen Evolution ◽  
Co2 Reduction ◽  
Hybrid Nanostructures

scholarly journals Photocatalytic CO2 Reduction and Electrocatalytic H2 Evolution over Pt(0,II,IV)-Loaded Oxidized Ti Sheets

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1909
Author(s):  
Ju Hyun Yang ◽  
So Jeong Park ◽  
Choong Kyun Rhee ◽  
Youngku Sohn
Keyword(s):  
Hydrogen Evolution ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Oxidation States ◽  
X Ray ◽  
Catalytic Activities ◽  
Before And After ◽  
Reduction Methods ◽  
Chemical States ◽  
Sputter Deposited

Energy recycling and production using abundant atmospheric CO2 and H2O have increasingly attracted attention for solving energy and environmental problems. Herein, Pt-loaded Ti sheets were prepared by sputter-deposition and Pt4+-reduction methods, and their catalytic activities on both photocatalytic CO2 reduction and electrochemical hydrogen evolution were fully demonstrated. The surface chemical states were completely examined by X-ray photoelectron spectroscopy before and after CO2 reduction. Gas chromatography confirmed that CO, CH4, and CH3OH were commonly produced as CO2 reduction products with total yields up to 87.3, 26.9, and 88.0 μmol/mol, respectively for 700 °C-annealed Ti under UVC irradiation for 13 h. Pt-loading commonly negated the CO2 reduction yields, but CH4 selectivity was increased. Electrochemical hydrogen evolution reaction (HER) activity showed the highest activity for sputter-deposited Pt on 400 °C-annealed Ti with a HER current density of 10.5 mA/cm2 at −0.5 V (vs. Ag/AgCl). The activities of CO2 reduction and HER were found to be significantly dependent on both the nature of Ti support and the oxidation states (0,II,IV) of overlayer Pt. The present result could provide valuable information for designing efficient Pt/Ti-based CO2 recycle photocatalysts and electrochemical hydrogen production catalysts.

Determination of growth regimes of Pd nanostructures on c-plane sapphire by the control of deposition amount at different annealing temperatures

2017 ◽  
Vol 19 (23) ◽  
pp. 15084-15097 ◽  
Author(s):  
Sundar Kunwar ◽  
Mao Sui ◽  
Puran Pandey ◽  
Quanzhen Zhang ◽  
Ming-Yu Li ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Solid State ◽  
Structural Evolution ◽  
Pd Nanoparticles ◽  
Annealing Temperatures ◽  
Deposition Amount ◽  
Sputter Deposited ◽  
Different Thickness

Semi-spherical and irregular Pd nanoparticles and voids are fabricated on sapphire(0001) by the solid-state dewetting of sputter-deposited Pd thin films at different thickness and temperature. The structural evolution, surface morphology transformation and optical properties of Pd nanostructures are probed.

Critical factors that determine face-centered cubic to body-centered cubic phase transformation in sputter-deposited austenitic stainless steel films

2004 ◽  
Vol 19 (6) ◽  
pp. 1696-1702 ◽  
Author(s):  
X. Zhang ◽  
A. Misra ◽  
R.K. Schulze ◽  
C.J. Wetteland ◽  
H. Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Phase Stability ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Bcc Structure ◽  
Face Centered ◽  
Sputter Deposited

Bulk austenitic stainless steels (SS) have a face-centered cubic (fcc) structure. However, sputter deposited films synthesized using austenitic stainless steel targets usually exhibit body-centered cubic (bcc) structure or a mixture of fcc and bcc phases. This paper presents studies on the effect of processing parameters on the phase stability of 304 and 330 SS thin films. The 304 SS thin films with in-plane, biaxial residual stresses in the range of approximately 1 GPa (tensile) to approximately 300 MPa (compressive) exhibited only bcc structure. The retention of bcc 304 SS after high-temperature annealing followed by slow furnace cooling indicates depletion of Ni in as-sputtered 304 SS films. The 330 SS films sputtered at room temperature possess pure fcc phase. The Ni content and the substrate temperature during deposition are crucial factors in determining the phase stability in sputter deposited austenitic SS films.

Nanosized LiNi1−xFexPO4embedded in a mesoporous carbon matrix for high-performance electrochemical water splitting

2015 ◽  
Vol 51 (87) ◽  
pp. 15815-15818 ◽  
Author(s):  
Shaojun Ma ◽  
Qing Zhu ◽  
Zhi Zheng ◽  
Wenlou Wang ◽  
Dongming Chen
Keyword(s):  
Water Splitting ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Mesoporous Carbon ◽  
High Performance ◽  
Carbon Matrix ◽  
Highly Effective ◽  
Electrochemical Water Splitting ◽  
First Time ◽  
Electrochemical Oxygen

This work reports for the first time LiNi1−xFexPO4@C nanocomposites as highly effective catalysts for electrochemical oxygen evolution reaction (OER).

scholarly journals Bayesian data analysis reveals no preference for cardinal Tafel slopes in CO2 reduction electrocatalysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Aditya M. Limaye ◽  
Joy S. Zeng ◽  
Adam P. Willard ◽  
Karthish Manthiram
Keyword(s):  
Data Analysis ◽  
Synthetic Data ◽  
Co2 Reduction ◽  
Tafel Slope ◽  
Bayesian Data Analysis ◽  
Electrochemical Catalyst ◽  
Current Voltage ◽  
Uncertainty Estimates ◽  
Tafel Slopes ◽  
Kinetic Investigations

AbstractThe Tafel slope is a key parameter often quoted to characterize the efficacy of an electrochemical catalyst. In this paper, we develop a Bayesian data analysis approach to estimate the Tafel slope from experimentally-measured current-voltage data. Our approach obviates the human intervention required by current literature practice for Tafel estimation, and provides robust, distributional uncertainty estimates. Using synthetic data, we illustrate how data insufficiency can unknowingly influence current fitting approaches, and how our approach allays these concerns. We apply our approach to conduct a comprehensive re-analysis of data from the CO2 reduction literature. This analysis reveals no systematic preference for Tafel slopes to cluster around certain "cardinal values” (e.g. 60 or 120 mV/decade). We hypothesize several plausible physical explanations for this observation, and discuss the implications of our finding for mechanistic analysis in electrochemical kinetic investigations.

scholarly journals Highly Efficient and Stable Hydrogen Production in All pH Range by Two-Dimensional Structured Metal-Doped Tungsten Semicarbides

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Edison H. Ang ◽  
Khang N. Dinh ◽  
Xiaoli Sun ◽  
Ying Huang ◽  
Jun Yang ◽  
...  
Keyword(s):  
Density Functional ◽  
Functional Theory ◽  
Faradaic Efficiency ◽  
Long Term Stability ◽  
Optimal Value ◽  
Tafel Slopes ◽  
Electrochemical Water Splitting ◽  
Ph Range ◽  
Metal Doped

Transition-metal-doped tungsten semicarbide nanosheets (M-doped W2C NSs, M=Fe, Co, and Ni) have been synthesized through carburization of the mixture of tungsten trioxide, polyvinylpyrrolidone, and metal dopant. The nanosheets grow directly on the W mesh and have the lateral dimension of several hundreds of nm to a few μm with a thickness of few tens nm. It is demonstrated that the M-doped W2C NSs exhibit superior electrocatalytic activity for hydrogen evolution reaction (HER). Impressively, the Ni-doped W2C NSs (2 at% Ni) with the optimized HER activity show extremely low onset overpotentials of 4, 9, and 19 mV and modest Tafel slopes of 39, 51, and 87 mV dec−1 in acidic (pH=0), neutral (pH=7.2), and basic (pH=14) solutions, respectively, which is close to the commercial Pt/C catalyst. Density functional theory (DFT) calculations also demonstrate that the Gibbs free energy for H adsorption of Ni-W2C is much closer to the optimal value ∆GH⁎ = -0.073 eV as compared to -0.16 eV of W2C. Furthermore, nearly 100% Faradaic efficiency and long-term stability are obtained in those environments. This realization of highly tolerant metal semicarbide catalyst performing on par with commercial Pt/C in all range of pH offers a key step towards industrially electrochemical water splitting.

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