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

Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  

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.

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  

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.


2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  

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.


Author(s):  
Sibimol Luke ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany V. Kerr ◽  
Jiban Kangsabanik ◽  
...  

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...


Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 826
Author(s):  
Junyu Chen ◽  
Jiamu Cao ◽  
Rongji Zhang ◽  
Jing Zhou ◽  
Shimin Wang ◽  
...  

Hydrogen-air proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are excellent fuel cells with high limits of energy density. However, the low carbon monoxide (CO) tolerance of the Pt electrode catalyst in hydrogen-air PEMFCs and methanol permanent in DMFCs greatly hindered their extensive use. Applying polybenzimidazole (PBI) membranes can avoid these problems. The high thermal stability allows PBI membranes to work at elevated temperatures when the CO tolerance can be significantly improved; the excellent methanol resistance also makes it suitable for DMFCs. However, the poor proton conductivity of pristine PBI makes it hard to be directly applied in fuel cells. In the past decades, researchers have made great efforts to promote the proton conductivity of PBI membranes, and various effective modification methods have been proposed. To provide engineers and researchers with a basis to further promote the properties of fuel cells with PBI membranes, this paper reviews critical researches on the modification of PBI membranes in both hydrogen-air PEMFCs and DMFCs aiming at promoting the proton conductivity. The modification methods have been classified and the obtained properties have been included. A guide for designing modifications on PBI membranes for high-performance fuel cells is provided.


2020 ◽  
Vol 30 (6) ◽  
pp. 855-860
Author(s):  
Ruixiang Wang ◽  
Pengyang Zhang ◽  
Yucheng Wang ◽  
Yuesheng Wang ◽  
Karim Zaghib ◽  
...  

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 437
Author(s):  
Yi Liu ◽  
Luofu Min ◽  
Wen Zhang ◽  
Yuxin Wang

In this article, we proposed a facile method to electrophoretically deposit a highly conductive and corrosion-resistant graphene layer on metal bipolar plates (BPs) while avoiding the oxidation of the metal substrate during the electrophoretic deposition (EPD). p-Phenylenediamine (PPD) was first grafted onto negatively charged graphene oxide (GO) to obtain modified graphene oxide (MGO) while bearing positive charges. Then, MGO dispersed in ethanol was coated on titanium plates via cathodic EPD under a constant voltage, followed by reducing the deposited MGO with H2 at 400 °C, gaining a titanium plate coated with reduced MGO (RMGO@Ti). Under the simulated environment of proton exchange membrane fuel cells (PEMFCs), RMGO@Ti presents a corrosion current of < 10−6 A·cm−2, approximately two orders of magnitude lower than that of bare titanium. Furthermore, the interfacial contact resistance (ICR) of RMGO@Ti is as low as 4 mΩ·cm2, which is about one-thirtieth that of bare titanium. Therefore, RMGO@Ti appears very promising for use as BP in PEMFCs.


2014 ◽  
Vol 2 (19) ◽  
pp. 7015-7019 ◽  
Author(s):  
He-Yun Du ◽  
Chen-Hao Wang ◽  
Chen-Shuan Yang ◽  
Hsin-Cheng Hsu ◽  
Sun-Tang Chang ◽  
...  

A well-controlled Pt/PBI–CNT electrode provides not only good interfacial continuity but also numerous edge planes, which has strong electrochemical activity in HT-PEMFCs.


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