Direct spectroscopic observation of proton exchange and Bjerrum defect migration in cubic ice

1980 ◽  
Vol 72 (12) ◽  
pp. 6807-6808 ◽  
Author(s):  
Gary Ritzhaupt ◽  
J. Paul Devlin
Keyword(s):  
Spectroscopic Observation ◽  
Proton Exchange ◽  
Defect Migration ◽  
Bjerrum Defect

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.

scholarly journals Spectroscopically evaluated rates and energies for proton transfer and Bjerrum defect migration in cubic ice

1984 ◽  
Vol 88 (3) ◽  
pp. 363-368 ◽  
Author(s):  
William B. Collier ◽  
Gary Ritzhaupt ◽  
J. Paul Devlin
Keyword(s):  
Proton Transfer ◽  
Defect Migration ◽  
Bjerrum Defect

scholarly journals In-situ spectroscopic observation of dynamic-coupling oxygen on atomically dispersed iridium electrocatalyst for acidic water oxidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hui Su ◽  
Wanlin Zhou ◽  
Wu Zhou ◽  
Yuanli Li ◽  
Lirong Zheng ◽  
...  
Keyword(s):  
Working Conditions ◽  
Water Oxidation ◽  
Active Sites ◽  
Proton Exchange Membrane ◽  
Large Mass ◽  
Spectroscopic Observation ◽  
Proton Exchange ◽  
Dynamic Coupling ◽  
Active Centre

AbstractUncovering the dynamics of active sites in the working conditions 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 the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N4 structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H2O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A gmetal−1 and a large turnover frequency of 5110 h−1 at a low overpotential of 216 mV (10 mA cm−2), 480–510 times larger than those of the commercial IrO2. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium.

Highly proton conductive membranes based on carboxylated cellulose nanofibres and their performance in proton exchange membrane fuel cells

2019 ◽  
Author(s):  
Valentina Guccini ◽  
Annika Carlson ◽  
Shun Yu ◽  
Göran Lindbergh ◽  
Rakel Wreland Lindström ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Surface Charge ◽  
Proton Exchange Membrane ◽  
Membrane Surface ◽  
Proton Exchange ◽  
Membrane Thickness ◽  
Fuel Cell Performance ◽  
Cellulose Nanofibres ◽  
Exchange Membrane

The performance of thin carboxylated cellulose nanofiber-based (CNF) membranes as proton exchange membranes in fuel cells has been measured in-situ as a function of CNF surface charge density (600 and 1550 µmol g<sup>-1</sup>), counterion (H<sup>+</sup>or Na<sup>+</sup>), membrane thickness and fuel cell relative humidity (RH 55 to 95 %). The structural evolution of the membranes as a function of RH as measured by Small Angle X-ray scattering shows that water channels are formed only above 75 % RH. The amount of absorbed water was shown to depend on the membrane surface charge and counter ions (Na<sup>+</sup>or H<sup>+</sup>). The high affinity of CNF for water and the high aspect ratio of the nanofibers, together with a well-defined and homogenous membrane structure, ensures a proton conductivity exceeding 1 mS cm<sup>-1</sup>at 30 °C between 65 and 95 % RH. This is two orders of magnitude larger than previously reported values for cellulose materials and only one order of magnitude lower than Nafion 212. Moreover, the CNF membranes are characterized by a lower hydrogen crossover than Nafion, despite being ≈ 30 % thinner. Thanks to their environmental compatibility and promising fuel cell performance the CNF membranes should be considered for new generation proton exchange membrane fuel cells.<br>

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