| 1. |
- Fan, Ke, et al.
(author)
-
Amorphous WO3 induced lattice distortion for a low-cost and high-efficient electrocatalyst for overall water splitting in acid
- 2020
-
In: Sustainable Energy & Fuels. - : ROYAL SOC CHEMISTRY. - 2398-4902. ; 4:4, s. 1712-1722
-
Journal article (peer-reviewed)abstract
- The development of highly active and durable catalysts for water oxidation under acidic conditions is necessary but challenging for renewable energy conversion. Ir-based catalysts are highly efficient for water oxidation in acid, but their large scale application is hindered by the high cost and scarcity of iridium. Herein, we use an amorphous WO3 induced lattice distortion (AWILD) strategy to reduce the Ir content to only 2 wt% in the final material. The optimized hybrid nitrogen-doped carbon (NC)/WO3/IrO2 can efficiently catalyze water oxidation with a low overpotential of 270 mV at 10 mA cm(-2) current density (eta (10)) and a high turnover frequency of over 2 s(-1) at 300 mV overpotential in 0.5 M H2SO4, a performance that surpasses that of commercial IrO2 significantly. Introducing the layer of amorphous WO3 between IrO2 nanoparticles and NC can distort the lattice of IrO2, exposing more highly active sites for water oxidation. The AWILD effect compensates for the lower Ir content and dramatically reduces the cost of the catalyst without sacrificing the catalytic activity. Additionally, this catalyst also exhibits high activity in acid for hydrogen evolution with only 65 mV of eta (10) attributed to the AWILD effect, exhibiting efficient bifunctionality as a Janus catalyst for overall water splitting. The AWILD approach provides a novel and efficient strategy for low-cost and highly efficient electrocatalysts for acidic overall water splitting with an extremely low content of noble metals.
|
|
| 2. |
- Fan, Ke, et al.
(author)
-
Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation
- 2018
-
In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 12:12, s. 12369-12379
-
Journal article (peer-reviewed)abstract
- As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported during the past few decades because of their high OER activities. It has been reported that electron-chemical conversion of metal OER chalcogenides into oxides/hydroxides would take place after the OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during the OER for these electrocatalysts, has not been understood yet; therefore a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale, is urgently needed. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in the OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of the electrocatalysts with a morphology change via Co(OH)(2) intermediate during the OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR), and other ex situ technologies. Moreover, on the basis of this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in the OER measurement can provide insights into the fundamental understanding of the mechanism for the OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.
|
|
| 3. |
- Fan, Ke, et al.
(author)
-
Hollow Iron-Vanadium Composite Spheres : A Highly Efficient Iron-Based Water Oxidation Electrocatalyst without the Need for Nickel or Cobalt
- 2017
-
In: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 56:12, s. 3289-3293
-
Journal article (peer-reviewed)abstract
- Noble-metal-free bimetal-based electrocatalysts have shown high efficiency for water oxidation. Ni and/or Co in these electrocatalysts are essential to provide a conductive, high-surface area and a chemically stable host. However, the necessity of Ni or Co limits the scope of low-cost electrocatalysts. Herein, we report a hierarchical hollow FeV composite, which is Ni- and Co-free and highly efficient for electrocatalytic water oxidation with low overpotential 390 mV (10 mA cm(-2) catalytic current density), low Tafel slope of 36.7 mV dec(-1), and a considerable durability. This work provides a novel and efficient catalyst, and greatly expands the scope of low-cost Fe-based electrocatalysts for water splitting without need of Ni or Co.
|
|
| 4. |
- Zhang, Youzi, et al.
(author)
-
Gradient Heating Epitaxial Growth Gives Well Lattice-Matched Mo2C-Mo2N Heterointerfaces that Boost Both Electrocatalytic Hydrogen Evolution and Water Vapor Splitting
- 2022
-
In: Angewandte Chemie International Edition. - : Wiley-Blackwell. - 1433-7851 .- 1521-3773. ; 61:47
-
Journal article (peer-reviewed)abstract
- An optimized approach to producing lattice-matched heterointerfaces for electrocatalytic hydrogen evolution has not yet been reported. Herein, we present the synthesis of lattice-matched Mo2C-Mo2N heterostructures using a gradient heating epitaxial growth method. The well lattice-matched heterointerface of Mo2C-Mo2N generates near-zero hydrogen-adsorption free energy and facilitates water dissociation in acid and alkaline media. The lattice-matched Mo2C-Mo2N heterostructures have low overpotentials of 73 mV and 80 mV at 10 mA cm(-2) in acid and alkaline solutions, respectively, comparable to commercial Pt/C. A novel photothermal-electrocatalytic water vapor splitting device using the lattice-matched Mo2C-Mo2N heterostructure as a hydrogen evolution electrocatalyst displays a competitive cell voltage for electrocatalytic water splitting.
|
|
| 5. |
- Zhou, Dinghua, et al.
(author)
-
WO3 Nanosheet-Supported IrW Alloy for High-Performance Acidic Overall Water Splitting with Low Ir Loading
- 2022
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 5:1, s. 970-980
-
Journal article (peer-reviewed)abstract
- Precious metals (like Ir, Ru, and Pt) and their derivatives are the benchmark catalysts for water splitting in acidic media due to their high stability and activity. However, the high cost and scarcity of these materials hamper the large-scale applications. To solve this issue, construction of catalysts containing low content of precious metals with high intrinsic activity can be an efficient strategy, which expectedly can decrease the cost but meanwhile preserve the activity. Herein, we synthesized an IrW/WO3 array catalyst by in situ formation of IrW alloy on hierarchical WO3 nanosheet arrays. With extremely low Ir content of 1.25 wt % in 0.5 M H2SO4, this composite catalyst not only shows superior water oxidation activity (the overpotential at 10 mA cm-2 is only 229 mV, significantly lower than that of the commercial IrO2 (358 mV)) but also exhibits excellent proton reduction performance (the overpotential at -10 mA cm-2 is 49 mV, close to that of commercial Pt/C catalyst (42 mV)), showing promising bifunctionality for the overall water splitting. As a result, only 1.5 V is needed to drive the overall water splitting at 10 mA cm-2 with a good long-term stability under acidic conditions. These remarkable features can be ascribed to the abundant active sites exposed by the three-dimensional nanostructure, and the high intrinsic activity per Ir site. The theoretical calculation verifies that Ir sites in IrW surface after oxidation have a higher intrinsic activity than IrO2 for water oxidation. We believe this research can supply a strategy to design highly active and stable catalysts with low loading of noble metals for acidic water splitting.
|
|
