bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Porous Molybdenum and Tungsten Carbides for Hydrogen Evolution Reaction Synthesized from a Sacrificial Leaching
Authors: Kim MinJoong , Song DongHoon , Oh SeKwon , Cho EunAe 
Published: February 2020

Hydrogen has been considered as one of the most promising energy source for future due to its high-energy density and no air pollutant emission. Water electrolysis into hydrogen and oxygen is an environmentally friendly method to produce hydrogen. Water electrolysis reaction is divided into two half reactions; hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). High overpotential of both HER and OER is the most significant problems to hamper reaction rate and overall efficiency of water electrolysis, which leads to increase in hydrogen production cost. Therefore, exploring active catalysts for HER and OER is one of the major issues in water electrolysis. Platinum (Pt) has been conventionally used as an efficient catalyst for HER. But, its high cost and scarceness is not suitable for a large-scale application of water electrolysis. As for the HER, the electrocatalytic activities of carbide materials, such as molybdenum carbide (Mo2C), and tungsten carbide (WC), have been remarkable among non-precious metal based catalysts. But, it is very difficult to synthesize nanostructured carbides, which is regarded as a main obstacle for increase in HER activity of such carbide based catalyts.
Herein, we report highly porous Mo2C and WC catalysts synthesized from a sacrificial leaching for hydrogen evolution reaction. We firstly synthesized Mo2C and WC composites with cobalt nanoparticles (Co-Mo2C and Co-WC) using graphitic carbon nitride (g-C3N4) as a carbon source, and then leached Co nanoparticles in 0.5 M sulfuric acid (H2SO4) solution. Through this sacrificial leaching method, we could successfully synthesize highly porous Mo2C and WC nanoparticles. Highly porous Mo2C and WC catalysts exhibited much enhanced HER activities in hydrogen saturated 0.5 M H2SO4 solution in comparison to Mo2C and WC nanoparticles synthesized from conventional carburizing method.
Fig. HER activities of highly porous and conventional Mo2C nanoparticles.

Figure 1
An Efficient and Robust Surface-Modified Iron Electrode for Oxygen Evolution in Alkaline Media
Authors: Mitra Debanjan , Narayanan S. R. 
Published: February 2020

The efficiency and cost of water electrolysis systems and rechargeable metal-air batteries can be improved by reducing the overpotential losses at the oxygen evolution electrode in alkaline medium. [1] Therefore, we seek inexpensive, efficient and durable electrocatalysts for the oxygen evolution reaction in alkaline medium. Transition metal oxides supported on nickel substrates have been the work-horse catalysts of industrial alkaline water electrolysis. But the cost added by nickel-based substrates can also be quite significant, and its replacement by less expensive materials is much desired. In our earlier study we had showed for the first-time that porous iron-sintered substrates modified by surface treatment using nickel can act as remarkably stable electrode when anodically polarized and also present a highly active electrocatalytic surface for the oxygen evolution reaction. [2] On these nickel modified sintered iron electrodes (NSI) we found an overpotential of 230 mV at 10 mA/cm2 (Figure 1 a).
In our quest for further improvements we have studied the effect of additive materials that can enhance the activity of NSI electrodes. Herein, we report a remarkably efficient and highly durable nickel modified iron electrode that has an iron sulfide additive (NSI-FeS) for oxygen evolution reaction. Such an electrode was prepared through a four-step process: (1) sintering of iron substrate along with 1 wt% of iron sulfide, (2) electrochemical oxidation of as-sintered electrode from open circuit potential to -0.6 V vs mercury-mercuric oxide electrode in 30 w/v % potassium hydroxide aqueous solution, (3) application of nickel coating and (4) calcination of nickel coating at 200o C. As-prepared NSI-FeS electrode exhibits an overpotential of ~200 mV to achieve 10 mA/cm2 current density with a Tafel slope of 46 mV/decade (Figure 1 a). The high activity for oxygen evolution may result from increased surface area obtained through electrochemical oxidation of iron substrate in presence of iron sulfide. The same electrode exhibits a highly stable overpotential for 1500 hours of testing at 10 mA/cm2 with an average change as small as 1 mV/1000 hour (Figure 1 b). Physical characterization methods such as XRD and XPS have been used to probe surface composition of the electrodes, and measurements for electrochemically active surface area were conducted through electrochemical impedance spectroscopy.
References:
[1] S. R. Narayan, A. K. Manohar and S. Mukerjee, Electrochem. Soc. Interface, 24.2 (2015): 65-69.
[2] D. Mitra, C. Yang, A. K. Manohar, P. Trinh, S .R. Narayanan, ECS Meeting Abstracts October 2016, No. 1, pp. 53-53.

Figure 1
An Alkaline Water Electrolyzer with Sustainion™ Membranes: 1 A/cm² at 1.9V with Base Metal Catalysts
Authors: Liu Zengcai , Sajjad Syed D. , Gao Yan , Kaczur Jerry , Masel Rich 
Published: February 2020

This paper will consider the effects of catalyst composition on alkaline membrane electrolyzers with Sustainion™ membranes. In previous work1, 2we have demonstrated that Sustainion™ membranes are stable at 60 °C for at least 1500 hours in 1 M KOH. Here we compare a number of base metal catalysts on the performance of an alkaline water electrolyzer.
Figure 1 shows the voltage needed to maintain 1 A/cm2 in an alkaline water electrolyzer running at 60 °C in 1 M KOH. The blue circles in Figure 1 were taken with nickel nanoparticles on carbon paper on both anode and cathode. Initially we observed good performance, with a cell voltage of 2.1 V but the voltage increased by about 110 µV/hr over the 2000 hour run. The voltage needed to maintain 1 A/cm2 decreased to 2.05 V when NiFeCo was substituted for Ni on the cathode, but we still observed a voltage rise of 44 µV/hr. We stopped the runs after 2000 hours and found that the membrane was still fine, but the carbon paper on the anode was degrading. So we replaced the carbon paper with metal cloth. We also substituted NiFeOx for Ni on the anode. The voltage needed to maintain 1 A/cm2 dropped to 1.9 V, and was stable for 500 hours. The run is continuing.
It is useful to compare our results to those from the recent literature. The best previous alkaline water electrolyzers with base metal catalysts ran at currents below 0.25 A/cm² at 2 V3, 4 and even precious metal catalysts have had trouble maintaining 1 A/cm2 at under 2 V5, 6. These results show that alkaline water electrolyzers with Sustainion™ membranes and base metal catalysts show near precious metal performance.
[1]. Kutz, R., Q. Chen, H. Yang, S.D. Sajjad, Z. Liu, and R.I. Masel, Sustainion™ Imidazolium Functionalized Polymers for CO2 Electrolysis.Energy Technology, 2017to appear.
[2]. Masel, R.I., Z. Liu, and S. Sajjad, Anion Exchange Membrane Electrolyzers Showing 1 A/cm2 at Less Than 2 V. ECS Transactions, 2016. 75: p. 1143-1146.
[3]. Zeng, K. and D. Zhang, Recent progress in alkaline water electrolysis for hydrogen production and applications. Progress in Energy and Combustion Science, 2010. 36: p. 307-326.
[4]. Bodner, M., A. Hofer, and V. Hacker, H2 generation from alkaline electrolyzer. Wiley Interdisciplinary Reviews: Energy and Environment, 2015. 4: p. 365-381.
[5]. Ahn, S.H., S.J. Yoo, H.-J. Kim, D. Henkensmeier, S.W. Nam, S.-K. Kim, and J.H. Jang, Anion exchange membrane water electrolyzer with an ultra-low loading of Pt-decorated Ni electrocatalyst. Applied Catalysis B: Environmental, 2016. 180: p. 674-679.
[6]. Leng, Y., G. Chen, A.J. Mendoza, T.B. Tighe, M.A. Hickner, and C.-Y. Wang, Solid-State Water Electrolysis with an Alkaline Membrane. Journal of the American Chemical Society, 2012. 134: p. 9054-9057.

Figure 1
Corrole Chelated Metal Complexes for HER and Oer
Authors: Mahammed Atif , Gross Zeev 
Published: February 2020

We have recently introduced corrole metal complexes (metallocorroles) as catalysts for various energy-relevant reactions. This includes those that are of prime importance for the electrochemical splitting of water into its elements, the hydrogen and oxygen evolution reactions. Tuning of the redox potentials, M(I)/M(II) for HER and M(III)/M(IV) for OER (M= Fe, Co, or Mn), is achieved via variations of substituents on the corrole ligand. These hypothesis-driven changes allow for the highly desired shifting of electrocatalytic onset potentials.
On top of the already published results listed below, new approaches and novel catalysts will be disclosed.
REFERENCES
“Cobalt Corrole Catalyst for Efficient Hydrogen Evolution Reaction from H2O under Ambient Conditions: Reactivity, Spectroscopy and DFT Calculations”, Inorg. Chem.
2013, 52, 3381-3387.
"The Cobalt Corrole Catalyzed Hydrogen Evolution Reaction: Surprising Electronic Effects and Characterization of Key Reaction Intermediates" Chem. Commun.
2014, 50, 2725-2727.
"Metallocorroles as photocatalysts for driving endergonic reactions, exemplified by bromide to bromine conversion", Angew. Chem.
2015, 54, 12370 –12373.
"Metallocorroles as Non-Precious Metal Catalysts for Oxygen Reduction", Angew. Chem.
2015
, 54, 14080 –14084.
“Metallocorroles as Non-Precious Metal Electrocatalysts for Highly Efficient Oxygen Reduction in Alkaline Media" ChemCatChem
2016, 8, 2832-2837.
“Metallocorroles as Electrocatalysts for the Oxygen Reduction Reaction (ORR)", Israel J. Chem.
2016, 56, 756– 762.
“Dioxygen bound Cobalt Corroles”, Chem. Commun. 2017, in press.
Performance of Pt-Ni Alloy Nanoparticles Supported on Carbon Nanotubes in Proton Exchange Membrane Fuel Cell
Authors: Cho Kuan Hsiu , Yeh Tsung-Kuang , Wang Mei-Ya 
Published: February 2020

Proton exchange membrane fuel cells (PEMFCs) have attracted a lot of attention for alternative and green energy sources owning to their low-carbon emissions and high efficiencies. Pt-based electrocatalysts used in PEMFC electrodes are the main contributor to the high cost. More research focusing on the use of Pt group alloys is still required to achieve enhanced catalytic activity while decreasing the Pt loading. In this study, Pt-Ni binary catalysts by pulse electrodeposition and electroless-deposition process were developed for the enhancement of oxygen reduction reaction. The Pt-Ni catalysts were deposited on carbon nanotubes (CNTs) directly grown on carbon cloths. CNTs used for catalyst nanostructured supports can decrease the needs of Pt and improve the performance of fuel cells. The nickel nanoparticles were deposited on CNTs by pulse electro-planting to form large-area flake structures. Then the platinum nanoparticles were reduced on them in a potassium hydroxide solution containing platinum precursor and ethylene glycol at 75 oC for the deposition time of 3, 4, 5 hours. The sample with the commercial Pt/C and Pt/CNTs were also prepared for comparison. Structure and elementary composition of catalysts were measured by SEM, XRD and ICP-MS. Ni/CNTs sample showed a uniform distribution of Ni nanoparticles on the surface of CNTs, which was provided for the deposition of Pt nanoparticles with average particle size of about 5 nm. Electrochemical characteristics of PtNi/CNTs and Pt/CNTs samples were investigated via cyclic voltammetry (CV) analysis and rotating disk electrode (RDE) test in 0.1 M perchloric acid solution. In terms of both limiting current density and onset potential, the PtNi/CNTs samples were better than those of Pt/CNTs samples. All PtNi/CNTs samples with different Pt deposition time showed very similar LSV curves using RDE tests. In single cell test, the PtNi/CNTs, as the cathode catalyst, has a higher maximum power density (763 mW/cm2) than the commercial Pt/C. Among the PtNi/CNTs samples, the better performance of PtNi/CNTs sample with 4-hours Pt deposition time can be attributed to the more convenient Pt availability for the oxygen reduction reaction (ORR). It can be also found that the open circuit voltage of this sample could reach up to 1V due to a significant decrease of the polarization loss. The main outcome of this study was that Pt–Ni binary alloy catalysts had better oxygen reduction reaction for cathode of PEMFC.
Self-Diffusion of Nafion Ionomer in Confined Nanopores
Authors: Islam Muhammad Naoshad , Pilapil Brandy , Trifkovic Milana , Karan Kunal 
Published: February 2020

Ordered nanoporous structures offer the advantage of high surface area and well-defined pathway for transport of charged and neutral species. Such structures with electronically conductive matrix are attractive option as alternative architecture for catalyst layers of polymer electrolyte fuel cells (PEFCs). However, the internal surface of these nanoporous material must be coated with sufficiently thin films of ionically conductive polymers (ionomers) while leaving pores still open for transport of reactants. One approach for achieving such thin films coatings is via self-diffusion of ionomers from its dispersion into the nanoporous structure. However, the efficacy of this process depends on various factors including the composition of the ionomer dispersion, which affects the aggregation state or shape/size of ionomer in the dispersion and the shape/size of the pores.
This work is concerned with the study of Nafion ionomer incorporation in model nanoporous structures with well-defined pore structure and size. A key challenge is quantification of the distribution of ionomer in these nanoporous structures. The thickness of ionomer films is anticipated to be a few nanometers, which limits the experimental observation to x-ray and electron microscopy based techniques both of which are known to damage polymers and also limit size of investigated volume of few tens of nanometers cubed. In this work, we have adopted laser scanning confocal fluorescence microscopy (LSCFM). The ionomer is first tagged with a fluophor. The tagged ionomer in dispersion diffuses through the pores of the nanoporous inorganic membranes of few tens of microns in thickness. The distribution of ionomer in the nanoporous membrane is mapped by LSCFM as function of pore size, ionomer concentration and exposure time. The figure below shows an example of Nafion ionomer distribution in anodized aluminum oxide nanoporous membrane.The results are cross-correlated with energy dispersive x-ray (EDX) characterization of selected samples. One of the peripheral questions, we wish to answer is whether Nafion ionomer can diffuse through sub-10 nm size pores that may exist in the secondary pores formed by aggregation of 30 nm Pt/C nanoparticle catalysts used for conventional catalyst layers of PEFCs. Furthermore, the methodology offers an attractive option for mapping long-range distribution of ionomer in tens of micron thick catalyst layers.

Figure 1
Preparation of PEMFC Electrodes from Milligram-Amount Catalysts
Authors: Yarlagadda Venkata , McKinney Samuel , Keary Cristin L , Thompson Levi T , Halevi Barr , Kongkanand Anusorn 
Published: February 2020

Thin film rotating disk electrode (RDE) measurements have been commonly used for activity and stability measurements of catalysts for proton exchange membrane fuel cells (PEMFCs). However, many catalysts that exhibit excellent activity and stability in an RDE do not show acceptable performance in an actual fuel cell using a membrane electrode assembly (MEA). This could be due to differences in the measurement conditions and the stability of the catalysts. This shows the importance of measuring the activity and durability of catalyst materials using an MEA in an actual fuel cell. However, MEA electrode preparation traditionally involves ink making and coating, processes that commonly require a large amount of catalyst material (>1 g) in order to prepare a well performing MEA. This creates a significant challenge for catalyst development because in early stages only mg amount are usually available and up-scaling efforts can be expensive and time consuming.
In this study, we developed two techniques to fabricate fuel cell electrodes from a small amount of catalyst (ca 30 mg): one using vacuum filtration and one using ultrasonic spray coater. The electrodes can then be used to fabricate MEAs. The fabrication procedure, the characterization of electrode quality, and the electrochemical properties will be discussed in comparison to MEA prepared by a traditional ‘large-catalyst-quantity’ process. A recommended procedure for MEA fabrication from mg-quantity catalyst samples will be provided.
This work was partially supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy under grant DE-EE0007271.
A Highly Efficient and Stable Pt/Coo/CN Electrocatalyst Obtained Based on Metal Organic Framework for PEMFC
Authors: Guo Wei 
Published: February 2020

A novel Co-based metal organic framework is synthesized in this study and used subsequently for the preparation of a Pt/CoO electrocatalyst with spherical structure. The catalyst prepared at 800 °C and the Pt co-doped into CoO nanoparticle surface to form a "Plum pudding" structure. This novel catalyst showed improved electrochemical performance and stability compared to commercial Pt/C catalyst.
Assessment of Hydrogen Peroxide Dismutation Rates: Detection of Oxygen and Peroxide on Se modified Pt Electrodes
Authors: Strobl Jonathan , Scherson Daniel 
Published: February 2020

The heterogeneous dismutation of hydrogen peroxide (HDHP) in aqueous electrolytes is an important but rarely addressed process that can play a critical role in the analysis of the data for the oxygen reduction reaction (ORR). On this basis, it is essential to develop reliable experimental methods for determining its rates and their dependence on among other factors the composition of the electrolyte. A potentially powerful method to evaluate the activity of materials for the HDHP reaction introduced decades ago by Anson and coworkers [1] relies of the use of a ring disk electrode whereby the disk is made of the material to be examined and the ring is used to detect oxygen generated by the disk via the HDHP in peroxide containing solutions. As discussed in the aforementioned publication, the ring must be active for the ORR, but inactive for the reduction of hydrogen peroxide, i.e. a strict two-electron reducer. Such conditions were achieved in that work by employing a ring modified with a transition metal macrocycle found to display these rather stringent conditions. The strategy employed in our group, involves the use of a Se-modified Pt ring electrode and takes advantage of the ability of this surface to reduce rather exclusively dioxygen to peroxide demonstrated earlier in our group in efforts aimed at the development of an oxygen concentrator [2].
As shown in Figure 1, a Pt disk electrode covered by 0.34 ML of Se polarized at 0.175 V vs RHE in 0.5 M H2SO4 is capable of yielding mass transport limited currents for the 2-electron reduction of oxygen to hydrogen peroxide [2], as evidenced by the slope of the Levich plot for ORR. However, statistical analysis of these data indicated a small positive intercept. Additional experiments in which peroxide was intentionally added to the solution gave rise to a rather linear increase in the magnitude of the intercept with peroxide concentration, without changing the slope of the Levich plot. This interesting behavior suggests that although Se modified Pt is largely selective towards the 2 electron reduction of oxygen, hydrogen peroxide also yields a small amount of current via some unidentified reaction. Mechanistic investigations are currently underway, and the possibility of using this electrode for oxygen and peroxide detection is also under investigation.
References:

Shigehara, K.; Anson, F. C. J. Phys. Chem.
1982, 86, 2776 – 2783.

Mo, Y.; Scherson, D. A. J. Electrochem. Soc.
2003, 150, E39 – E46.

Figure 1
On the Experimental Investigation of the Clamping Pressure Effects on the Proton Exchange Membrane Water Electrolyser Cell Performance
Authors: Al Shakhshir Saher , Frensch Steffen , Kær Søren Knudsen 
Published: February 2020

The intermittent renewable and power energy sources can be effectively utilized using hydrogen energy storage technology. Hydrogen has the highest energy capacity per unit weight of any known other fuel. Also it is considered as a promising energy carrier and a future replacement for fossil fuel energy sources. The proton exchange membrane water electrolyser (PEMWE) is the most candidate technology to produce hydrogen from renewable energy sources. PEMWE cell splits water into hydrogen and oxygen when an electric current is passed through it. Electrical current forces the positively charged ions to migrate to negatively charged cathode, where hydrogen is reduced. Meanwhile, oxygen is produced at the anode side electrode and escape as a gas with the circulating water.
In the recent few years, PEMWE’s R&D has inched towards; operating conditions; such as increased operating temperature and cathode-anode high differential pressure operation, flow field design, stack development, and modeling. In this work the effect of clamping pressure on the PEMWE cell performance is studied. A 50 cm2 active area PEMWE cell with double serpentine flow field channels for the anode and cathode side is used. The standard electrochemical technique to characterize the performance of electrochemical cells is the polarization curve. Thus, the IV curves are measured at different clamping pressures. Also, the electrochemical impedance spectroscopy (EIS) is used as a non-invasive technique to characterize the electrochemical processes at different clamping pressures. All these measurements are conducted at constant cell temperature (70°C) and atmospheric pressure. Furthermore, to ensure a high confidence level in the obtained data, experiments are repeated few times.
Early results for polarization curve predict that the PEMWE cell performance increases with increasing the clamping pressure at fixed temperature and current density. This can be elucidated by the EIS measurements which predict an increment in ohmic and activation resistance at lower clamping pressure values for the same temperature and current density.

Figure 1