Mixed metal-antimony oxide nanocomposites: low pH water oxidation electrocatalysts with outstanding durability at ambient and elevated temperatures

2021 ◽  
Author(s):  
Sibimol Luke ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany V. Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Energy Efficient ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Low Ph ◽  
Proton Exchange ◽  
Efficient Production ◽  
Current Technology ◽  
Exchange Membrane

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H2, but the current technology relies on high loadings of expensive iridium at the anodes, which are often...

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
High Performance ◽  
Density Functional ◽  
High Stability ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Ambient Conditions

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H<sub>2</sub>, but the current technology relies on high loadings of expensive iridium at the anodes, which are often unstable in operation. To address this, the present work scrutinises the properties of antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as flat thin films by a solution-based method for the oxygen evolution reaction in 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the non-noble-metal catalysts, only cobalt-antimony and manganese-antimony oxides demonstrate high stability and reasonable activity under ambient conditions, but slowly lose activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and remaining remarkably stable during one-week tests at 80 °C. The <i>S</i>-number for this catalyst is higher than that for the high-performance benchmark Ir-based systems. Density functional theory analysis and physical characterisation reveal that this high stability is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by antimony, and can arise from two distinct structural scenarios: either formation of an antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites.

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
High Performance ◽  
Density Functional ◽  
High Stability ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Ambient Conditions

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H<sub>2</sub>, but the current technology relies on high loadings of expensive iridium at the anodes, which are often unstable in operation. To address this, the present work scrutinises the properties of antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as flat thin films by a solution-based method for the oxygen evolution reaction in 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the non-noble-metal catalysts, only cobalt-antimony and manganese-antimony oxides demonstrate high stability and reasonable activity under ambient conditions, but slowly lose activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and remaining remarkably stable during one-week tests at 80 °C. The <i>S</i>-number for this catalyst is higher than that for the high-performance benchmark Ir-based systems. Density functional theory analysis and physical characterisation reveal that this high stability is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by antimony, and can arise from two distinct structural scenarios: either formation of an antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites.

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Density Functional ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Highly Active ◽  
Antimony Oxides ◽  
Electrochemical Water Splitting

Electrochemical water splitting with a proton-exchange membrane electrolyte provides many advantages for the energy-efficient production of high-purity H<sub>2</sub> in a sustainable manner, but the current technology relies on high loadings of expensive and scarce iridium at the anodes, which are also often unstable in operation. To address this, the present work scrutinises the electrocatalytic properties of a range of mixed antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as thin films by a simple solution-based method for the oxygen evolution reaction in aqueous 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the noble-metal free catalysts, cobalt-antimony and manganese-antimony oxides demonstrate good stability over 24 h and reasonable activity at 24 ± 2 °C, but slowly lose their initial activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of only 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and most importantly, remaining remarkably stable during one-week tests at 80 °C. Detailed characterisation reveals that the enhanced stability of metal-antimony oxides water oxidation catalysts can arise from two distinct structural scenarios: either formation of a new antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites. Density functional theory analysis further indicates that the stability in operation is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by the presence of Sb.

Defects tailoring IrO2@TiN1+x nano-heterojunction for superior water oxidation activity and stability

2021 ◽  
Author(s):  
Sen Wang ◽  
Hong Lv ◽  
Songhu Bi ◽  
Tianqi Li ◽  
Yongwen Sun ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Proton Exchange Membrane ◽  
Water Electrolysis ◽  
Cost Effective ◽  
Proton Exchange ◽  
Pragmatic Approach ◽  
Oxidation Activity ◽  
Anode Catalysts ◽  
Exchange Membrane

Developing cost-effective Ir-based anode catalysts for proton exchange membrane (PEM) water electrolysis has been recognized as an efficient and pragmatic approach, however, many challenges remain to lower Ir content while...

scholarly journals Electrochemical characterization of manganese oxides as a water oxidation catalyst in proton exchange membrane electrolysers

2019 ◽  
Vol 6 (5) ◽  
pp. 190122 ◽  
Author(s):  
Toru Hayashi ◽  
Nadège Bonnet-Mercier ◽  
Akira Yamaguchi ◽  
Kazumasa Suetsugu ◽  
Ryuhei Nakamura
Keyword(s):  
Water Oxidation ◽  
Manganese Oxides ◽  
Proton Exchange Membrane ◽  
Water Electrolysis ◽  
Electrode System ◽  
Proton Exchange ◽  
Oxidation Catalyst ◽  
Carbon Supports ◽  
Exchange Membrane ◽  
Mn Oxides

The performance of four polymorphs of manganese (Mn) dioxides as the catalyst for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) electrolysers was examined. The comparison of the activity between Mn oxides/carbon (Mn/C), iridium oxide/carbon (Ir/C) and platinum/carbon (Pt/C) under the same condition in PEM electrolysers showed that the γ-MnO 2 /C exhibited a voltage efficiency for water electrolysis comparable to the case with Pt/C, while lower than the case with the benchmark Ir/C OER catalyst. The rapid decrease in the voltage efficiency was observed for a PEM electrolyser with the Mn/C, as indicated by the voltage shift from 1.7 to 1.9 V under the galvanostatic condition. The rapid deactivation was also observed when Pt/C was used, indicating that the instability of PEM electrolysis with Mn/C is probably due to the oxidative decomposition of carbon supports. The OER activity of the four types of Mn oxides was also evaluated at acidic pH in a three-electrode system. It was found that the OER activity trends of the Mn oxides evaluated in an acidic aqueous electrolyte were distinct from those in PEM electrolysers, demonstrating the importance of the evaluation of OER catalysts in a real device condition for future development of noble-metal-free PEM electrolysers.

scholarly journals Operando spectroscopic observation of dynamic-coupling oxygen on single-atomic iridium catalyst for acidic water oxidation

2021 ◽  
Author(s):  
Hui Su ◽  
Wanlin Zhou ◽  
Wu Zhou ◽  
Yuanli Li ◽  
Li Rong Zheng ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Active Sites ◽  
Proton Exchange Membrane ◽  
Large Mass ◽  
Spectroscopic Observation ◽  
Proton Exchange ◽  
Dynamic Coupling ◽  
Exchange Membrane ◽  
X Ray Absorption ◽  
Increased Activity

Abstract Uncovering the dynamics of active sites under working state is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at atomic level a potential-driven dynamic-coupling oxygen on the hetero-nitrogen configured single-atomic Ir sites (HN-Ir NC) during OER working conditions to successfully endow the single-atomic Ir catalyst with an ultrahigh electrochemical acidic-OER activity. Using operando synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe in the experiment that a dynamic oxygen atom is formed at the Ir site with the O-hetero-Ir-N4 structure as more electrophilic active center and then effectively promote the generation of the key *OOH intermediates under working potentials, which is exceptionally favourable for the dissociation of H2O over Ir sites and resistance to over-oxidation and dissolution of the active sites.The optimal single-atomic HN-Ir NC catalyst delivers a large mass activity of 2860 A gmetal−1 and a huge turnover frequency of 5110 h− 1 at a low overpotential of 216 mV (10 mA cm− 2), 480˗510 times than that of commercial IrO2 catalyst. More importantly, the HN-Ir NC catalyst shows no evident deactivation after continuous 100 h OER operation in acidic medium.

Effect of Elevated PEM Fuel Cell Operating Temperature (120°C and 140°C) and Membrane Thickness on Proton Conductivity for Combat Vehicle Use

2020 ◽  
Author(s):  
Theodore Burye
Keyword(s):  
Proton Conductivity ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Operating Temperature ◽  
Electrical Power ◽  
Proton Exchange ◽  
Membrane Thickness ◽  
Membrane Degradation ◽  
Combat Vehicle ◽  
Exchange Membrane

Electrical power required to operate vehicles in the U.S. Army is increasing due to expanding mission requirements, such as silent watch, exportable power, and powerful onboard electronics. Proton Exchange Membrane Fuel Cells (PEMFCs) provide a solution, but stack thermal-cycling, electrocatalyst and membrane degradation losses need to be reduced before integration of PEMFCs can be realized. Membrane thermal degradation is exacerbated by poor heat rejection (as ballistic grills impede airflow) which can raise stack temperatures ≥140°C. Commercial PEMFCs operate ~65°C so elevated temperatures could degrade the membrane. Nafion 115 (127 μm), 117 (183 μm) and 1110 (254 μm) membranes submerged in 16 MΩ water were heated between 65-140°C to investigate elevated temperature and membrane thickness on proton conductivity. EIS results showed sample thickness did not statistically impact conductivity overall. Conductivity, however, was impacted for temperatures &gt;100°C with each material. Overall, these materials are not suitable when operating PEMFCs above 100°C.

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