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Rice is a predominant food crop that was extensively cultivated and consumed in India. Recently, small and fragmented land holdings and labour scarcity during the peak season are driving farmers toward farm mechanization. Villupuram is one of the prominent districts with the maximum area under rice cultivation. The study was conducted to examine the adoption level of various recommended implements and machinery by rice farmers in the Villupuram district. Of the 13 blocks of Villupuram district three blocks were selected for this study. A total of 120 farmers were selected for the study using a proportionate random sampling method. This study was conducted during April and may 2022. Ex-post facto research design was used for the study. Data were collected using a well-structured and pre-tested interview schedule. The findings of the study revealed that most respondents had a medium level of adoption of farm implements and machinery in rice cultivation. Most respondents adopted a combined harvester, tractor, power tiller, rotavator and power sprayer. None of the respondents adopted bund maker, seed cum fertilizer drill, rice cum Daincha seeder, rotary weeder, power weeder, drone operated sprayer, reaper and thresher. Custom hiring facilities are required to rent the equipment on a payment basis and awareness should be made on specific equipment like, seed cum fertilizer drill, power weeder, Conoweeder and rotary weeder.

Nowadays usage of Social media is increasing rapidly in the 21st century. WhatsApp is the most popular social media which is used by a large number of people. The present study was focused on how effectively KVK's farmers use WhatsApp groups for agricultural purposes. Three districts of Cauvery Delta Zone Nagapattinam, Thiruvarur, and Karaikal KVK WhatsApp groups were purposively selected for the study. Totally 120 farmers were selected for primary data, and from each district, 40 farmers were selected by the Simple Random Sampling method. Data were analyzed by descriptive statistics. It reported that the overall effectiveness of the farmer's use of WhatsApp groups was at the medium level (74.17%) indicating that farmers were using the group for their agricultural activities. The easiness of understanding information on Whatsapp was found to be good, and image and video-based information, in addition to textual information aided in a better understanding of information. Based on the study recommended that is important to be placed on disseminate weather and market information to aid indecision making.

AIM: To Determine the Prognostic Value Of 2D- Right ventricle Free Wall Longitudinal Strain In Patients With Acute Decompensated Heart Failure. BACKGROUND Ÿ The prognostic impact of 2-dimensional strain is unclear in patients with acute decompensated heart failure (HF). Ÿ we investigate whether left ventricular and right ventricular (RV) strain parameters assessed by speckle tracking echocardiography provide incremental prognostic information in hospitalized patients because of acute decompensated HF. METHODS AND RESULTS Ÿ FOURTY SIX patients (age, 54±9 years; 6.5% women; ejection fraction, 36±5%) hospitalized for acute decompensated HF underwent clinical and echocardiographic evaluation just before discharge. We performed strain analyses of left ventricular global longitudinal strain and RV longitudinal strain only from the free wall (RV-fwLS) and from all segments of the RV global longitudinal strain wall by echocardiogram. The primary composite end point was cardiovascular death and readmission for HF. There were 30.4% cardiac events during a median follow-up of 180 days. Among echocardiographic parameters, only impaired RV-fwLS (Less Than 11.4±4.9) was independently associated with cardiac events. Adding RV-fwLS to clinical risk evaluation (age, New York Heart Association class III/IV, blood urea nitrogen, and brain natriuretic peptide) markedly improved prognostic utility. CONCLUSIONS: Ÿ RV-fwLS is an independent predictor of cardiac events in acute decompensated HF. Although there are various standard echocardiographic parameters, RV-fwLS has improved prognostic utility.

We have statistically analyzed 379 radio-loud (RL) CMEs and their associated flares during the period 1996 - 2019 covering both solar cycles (SC) 23 and 24. We classified them into two sets of populations based on the observation period: i) 235 events belong to SC 23 (August 1996 - December 2008) and ii) 144 events belong to SC 24 (January 2009 - December 2019). The average residual acceleration of RL CMEs in SC 24 (--17.39 $\pm$ 43.51 m s$^{-2}$) is two times lower than that of the RL CMEs in SC 23 (--8.29 $\pm$ 36.23 m s$^{-2}$), which means that deceleration of RL CMEs in SC 24 is twice as fast as in SC 23. RL CMEs of SC 23 (1443 $\pm$ 504 km s$^{-1}$; 13.82 $\pm$ 7.40 \emph{R}$_{\circledcirc}$) reach their peak speed at higher altitudes than RL CMEs of SC 24 (1920 $\pm$ 649 km s$^{-1}$; 12.51 $\pm$ 7.41 \emph{R}$_{\circledcirc}$).We also observed that the mean apparent widths of RL CMEs in SC 23 are less than in SC 24which is statistically significant. SC 23 has a lower average CME nose height (3.85 \emph{R}$_{\circledcirc}$) at the start time of DH type II bursts than that of SC 24 (3.46 \emph{R}$_{\circledcirc}$). The starting frequencies of DH type II bursts associated with RL CMEs for SC 24 are significantly larger (formed at lower heights) than that of SC 23. We found that there is a good correlation between the drift rates and the mid-frequencies of DH type II radio bursts for both the solar cycles (\emph{R} = 0.80, $\epsilon$ = 1.53). Most of the RL CMEs kinematics and their associated solar flare properties are found similar for SC 23 and SC 24. We concluded that the reduced total pressure in the heliosphere for SC 24 enables RL CMEs to expand wider and decelerate faster, resulting in DH type II radio emissions at lower heights than SC 23., Comment: 18pages, 6 figures, 1 table

Additional file 2: Case report form booklet

Additional file 1: List of participating sites with investigators

Additional file 3: Standard operating procedure

We present a detailed analysis of a long-duration flare associated with a coronal mass ejection (CME) event that occurred on 27 January 2012 in the active region (AR) 11402. We analyze the kinematics of the CME and the close relationship between the flare, radio burst, and CME. We used STEREO (Solar Terrestrial Relations Observatory)/EUVI A (Extreme Ultraviolet Imager) and white light data from STEREO (COR1 A and COR2 A) and LASCO (Large Angle and Spectrometric COronagraph) (C2/C3) coronagraphs, and X-ray data from the GOES (Geostationary Operational Environmental Satellite) spacecraft. The height of the CME is measured using the Graduated Cylindrical Shell (GCS) model. Our results show that: i) the speed of the CME (1460 km/s at $2.54~\mbox{R}_{\odot}$ ) is comparable to the speed of the type II radio burst (1581 km/s), ii) the height of the type II radio burst is lower than that of the CME leading edge, iii) the CME acceleration phase is found to be related to the rise time of the flare and its propagation phase is related to the decay phase of the flare, iv) the type II radio burst origin is likely to be near the CME region where a CME-streamer interaction takes place around $1.6~\mbox{R}_{\odot}$ , and v) the sequence of events and the CME kinematics show a close association between the CME and type II radio emissions.

We study the characteristics of the CMEs and their association with the end-frequency of interplanetary (IP)-type-II bursts by analyzing a set of 138 events (IP-type-II bursts–flares–CMEs) observed during the period 1997–2012. The present analysis consider only the type II bursts having starting frequency $< 14~\mbox{MHz}$ to avoid the extension of coronal type IIs. The selected events are classified into three groups depending on the end-frequency of type IIs as follows, (A) Higher, (B) Intermediate and (C) Lower end-frequency. We compare characteristics of CMEs, flares and type II burst for the three selected groups of events and report some of the important differences. The observed height of CMEs is compared with the height of IP type IIs estimated using the electron density models. By applying a density multiplier ( $m$ ) to this model, the density has been constrained both in the upper corona and in the interplanetary medium, respectively as $m= 1 \mbox{ to } 10$ and $m = 1 \mbox{ to } 3$ . This study indicates that there is a correlation between the observed CME height and estimated type II height for groups B and C events whereas this correlation is absent in group A. In all the groups (A, B & C), the different heights of CMEs and type II reveal that the type IIs are not only observed at the nose but also at the flank of the CMEs.

We perform a statistical analysis on 157 M-class soft X-ray flares observed during 1997 – 2014 with and without deca-hectometric (DH) type II radio bursts aiming at the reasons for the non-occurrence of DH type II bursts in certain events. All the selected events are associated with halo Coronal Mass Ejections (CMEs) detected by the Solar and Heliospheric Observatory (SOHO) / Large Angle Spectrometric and COronograph (LASCO). Out of 157 events, 96 (61%; “Group I”) events are associated with a DH type II burst observed by the Radio and Plasma Wave (WAVES) experiment onboard the Wind spacecraft and 61 (39%; “Group II”) events occur without a DH type II burst. The mean CME speed of Group I is $1022~\mbox{km}/\mbox{s}$ and that of Group II is $647~\mbox{km}/\mbox{s}$ . It is also found that the properties of the selected M-class flares such as flare intensity, rise time, duration and decay time are greater for the DH associated flares than the non-DH flares. Group I has a slightly larger number (56%) of western events than eastern events (44%), whereas Group II has a larger number of eastern events (62%) than western events (38%). We also compare this analysis with the previous study by Lawrance, Shanmugaraju, and Vrsnak (Solar Phys. 290, 3365L, 2015) concerning X-class flares and confirm that high-intensity flares (X-class and M-class) have the same trend in the CME and flare properties. Additionally we consider aspects like acceleration and the possibility of CME-streamer interaction. The average deceleration of CMEs with DH type II bursts is weaker ( $a = - 4.39\mbox{ m}/\mbox{s}^{2}$ ) than that of CMEs without a type II burst ( $a = -12.21\mbox{ m}/\mbox{s}^{2}$ ). We analyze the CME-streamer interactions for Group I events using the model proposed by Mancuso and Raymond (Astron. Astrophys. 413, 363, 2004) and find that the interaction regions are the most probable source regions for DH type II radio bursts.

Background: Acute myocardial infarction (MI) is a significantly raising problem particularly in India. The various aspects of myocardial infarction such as risk factor profiles, clinical presentations and prognosis differ significantly in south Indian people when compared to others. This study was undertaken to study the association of socio-demographic and life-style factors with acute myocardial infarction in South India.Material: This was a prospective study included 100 patients admitted in ICCU for acute MI in Government Rajaji Hospital Madurai over a period of 1 year. History, ECG, CPK-MB, and 2-D Echo was done to diagnose MI.Results: In this study, 68% patients were males. In this study, 34% patients had diabetes, 42% had hypertension, 58% were smokers. In our study 70% patients had BMI between 25-30kg/m2. In this study, 86% patients had TGL more than 200mg/dl, 28% patients had LDL more than 100 mg/dl and 78% patients had NON-HDL more than 130 mg/dl. In this study, 9 patients had depression. In our study 61% male patients had waist hip ratio more than >1 and in females 69% patients had waist hip ratio more than >0.85. In our study, 22% patients had hemoglobin >16g/dl.Conclusion: Prevention of coronary artery syndrome by modifying the risk factors were crucial. Serum cholesterol, LDL cholesterol, BMI were not significant to predict ACS in our study Waist Hip ratio, Triglyceride, Non-HDL cholesterol, smoking and Depression were significant to predict acute coronary syndrome in this study.

As Polymer Electrolyte Fuel Cells (PEFCs) are nearing the acceptable performance level for automotive and stationary applications, the focus on the research is shifting more and more toward enhancing their durability that still remains a major concern in their commercial acceptability. Hydrous ruthenium oxide (RuO2) is a promising material for pseudocapacitors due to its high stability, high specific-capacitance and rapid faradaic-reaction. Incorporation of carbon-supported RuO2 (RuO2/C) to platinum (Pt) is found to ameliorate both stability and catalytic activity of fuel cell cathodes that exhibit higher performance and durability in relation to Pt/C cathodes as evidenced by cell polarization, impedance and cyclic voltammetry data. The degradation in performance of Pt-RuO2/C cathodes is found to be only similar to 8% after 10000 accelerated stress test (AST) cycles as against similar to 60% for Pt/C cathodes after 7000 AST cycles under similar conditions. These data are in conformity with the Electrochemical Surface Area and impedance results. Interestingly, Pt-RuO2/C cathodes can withstand more than 10000 AST cycles with only a nominal loss in their performance. Studies on catalytic electrodes with X-ray diffraction, transmission electron microscopy and cross-sectional field-emission scanning electron microscopy reflect that incorporation of RuO2 to Pt helps mitigating aggregation of Pt particles and improves its stability during long-term operation of PEFCs. (C) 2012 The Electrochemical Society. DOI: 10.1149/2.jes113440] All rights reserved.

Long-term deterioration in the performance of PEFCs is attributed largely to reduction in active area of the platinum catalyst at cathode, usually caused by carbon-support corrosion. It is found that the use of graphitic carbon as cathode-catalyst support enhances its long-term stability in relation to non-graphitic carbon. This is because graphitic-carbon-supported- Pt (Pt/GrC) cathodes exhibit higher resistance to carbon corrosion in-relation to non-graphitic-carbon-supported- Pt (Pt/Non-GrC) cathodes in PEFCs during accelerated stress test (AST) as evidenced by chronoamperometry and carbon dioxide studies. The corresponding change in electrochemical surface area (ESA), cell performance and charge-transfer resistance are monitored through cyclic voltammetry (CV), cell polarisation and impedance measurements, respectively. The degradation in performance of PEFC with Pt/GrC cathode is found to be around 10% after 70 h of AST as against 77% for Pt/Non-GrC cathode. It is noteworthy that Pt/GrC cathodes can withstand even up to 100 h of AST with nominal effect on their performance. Xray diffraction (XRD), Raman spectroscopy, transmission electron microscopy and cross-sectional field-emission scanning electron microscopy (FE-SEM) studies before and after AST suggest lesser deformation in catalyst layer and catalyst particles for Pt/GrC cathodes in relation to Pt/Non-GrC cathodes, reflecting that graphitic carbon-support resists carbon corrosion and helps mitigating aggregation of Pt-particles.

Carbon-supported Pt–Au (Pt–Au/C) catalyst is prepared separately by impregnation, colloidal and micro-emulsion methods, and characterized by physical and electrochemical methods. Highest catalytic activity towards oxygen-reduction reaction (ORR) is exhibited by Pt–Au/C catalyst prepared by colloidal method. The optimum atomic ratio of Pt to Au in Pt–Au/C catalyst prepared by colloidal method is determined using linear-sweep and cyclic voltammetry in conjunction with cell-polarization studies. Among 3:1, 2:1 and 1:1 Pt–Au/C catalysts, (3:1) Pt–Au/C exhibits maximum electrochemical activity towards ORR. Powder X-ray diffraction pattern and transmission electron micrograph suggest Pt–Au alloy nanoparticles to be well dispersed onto the carbon-support. Energy dispersive X-ray analysis and inductively coupled plasma-optical emission spectroscopy data suggest that the atomic ratios of the alloying elements match well with the expected values. A polymer electrolyte fuel cell (PEFC) operating at 0·6 V with (3:1) Pt–Au/C cathode delivers a maximum power-density of 0·65 W/cm 2 in relation to 0·53 W/cm 2 delivered by the PEFC with pristine carbon-supported Pt cathode.

Platinum loading as low as 0.05 mg/cm2 at the anode of the PEFC is desired for automotive applications. Hence, it is necessary to quantify the performance losses that may arise on reducing anode Pt loading from the present level of about 0.5 mg/cm2 to 0.05 mg/cm2. The present study focuses on hydrogen oxidation reaction for fuel cell anode with low Pt loadings. Hydrogen-pump experiments are conducted in conjunction with polarization studies to determine the performance losses at reduced Pt loadings arising due to Hydrogen Oxidation Reaction (HOR) and Hydrogen Evolution Reaction (HER).

A Pt-Au alloy catalyst of varying compositions is prepared by codeposition of Pt and Au nanoparticles onto a carbon support to evaluate its electrocatalytic activity toward an oxygen reduction reaction (ORR) with methanol tolerance in direct methanol fuel cells. The optimum atomic weight ratio of Pt to Au in the carbon-supported Pt-Au alloy (Pt-Au/C) as established by cell polarization, linear-sweep voltammetry (LSV), and cyclic voltammetry (CV) studies is determined to be 2:1. A direct methanol fuel cell (DMFC) comprising a carbon-supported Pt-Au (2:1) alloy as the cathode catalyst delivers a peak power density of 120 mW/cm2 at 70 °C in contrast to the peak power density value of 80 mW/cm2 delivered by the DMFC with carbon-supported Pt catalyst operating under identical conditions. Density functional theory (DFT) calculations on a small model cluster reflect electron transfer from Pt to Au within the alloy to be responsible for the synergistic promotion of the oxygen-reduction reaction on a Pt-Au electrode.

Sol–gel derived mesoporous carbon (MC) for the preparation of gas-diffusion layer (GDL) and its ameliorating effect on the performance of polymer electrolyte fuel cells (PEFCs) is reported. MC with a specific surface area of 370 m2/g, pore diameter of 6.7 nm and pore volume of 0.45 cm3/g has been synthesized by co-assembly of a tri-block copolymer, namely pluronic-F127, as a structure directing agent, and a mixture of phloroglucinol and formaldehyde as carbon precursor. X-ray diffraction and transmission electron microscopy have been employed to examine the structural properties of the MC. Surface morphology of the GDL comprising MC has been studied by scanning electron microscopy. A peak power density of 0.53 W/cm2 at a load current-density of 1.1 A/cm2 is achieved for the PEFC employing electrodes with GDL of MC compared to the peak power density of 0.47 W/cm2 at a load current-density of 0.93 A/cm2 for the PEFC employing electrodes with GDL of commercial Vulcan XC-72R carbon, while operating at 70 oC with H2 and air feeds at atmospheric pressure.

Poly(styrene sulfonic acid) (PSSA) content in poly(vinyl alcohol) (PVA) and PSSA blend membrane is varied and its effect on proton conductivity is studied at varying relative humidity (RH) values. The maximum proton conductivity is observed for the PVA-PSSA membrane with about 35 wt. % PSSA at all humidity values. At 30% RH value, the conductivity of PVA-PSSA blend membrane is 1.20 � 10-3 S/cm, which is about two orders of magnitude higher than the conductivity value of 2.27 � 10-5 S/cm observed for pristine PVA membrane. Water self-diffusion coefficients and water release kinetics of these materials have been characterized by nuclear magnetic resonance (NMR) imaging technique, which validate the use of this membrane in polymer electrolyte fuel cells (PEFCs). A peak power density of 210 mW/cm2 at a load current-density of 500 mA/cm2 is achieved for the PEFC with the optimized PVA-PSSA membrane as electrolyte compared to a peak power density of only 38 mW/cm2 observed at a load current-density of 80 mA/cm2 for the PEFC with pristine PVA membrane as electrolyte while operating at 75 �C with H2 and O2 feeds to the fuel cell maintained at atmospheric pressure. � 2008 Elsevier B.V. All rights reserved.

A direct borohydride-hydrogen peroxide fuel cell employing carbon-supported Prussian Blue (PB) as mediated electron-transfer cathode catalyst is reported. While operating at 30 °C, the direct borohydride-hydrogen peroxide fuel cell employing carbon-supported PB cathode catalyst shows superior performance with the maximum output power density of 68 mW cm−2 at an operating voltage of 1.1 V compared to direct borohydride-hydrogen peroxide fuel cell employing the conventional gold-based cathode with the maximum output power density of 47 mW cm−2 at an operating voltage of 0.7 V. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX) suggest that anchoring of Cetyl-Trimethyl Ammonium Bromide (CTAB) as a surfactant moiety on carbon-supported PB affects the catalyst morphology. Polarization studies on direct borohydride-hydrogen peroxide fuel cell with carbon-supported CTAB-anchored PB cathode exhibit better performance with the maximum output power density of 50 mW cm−2 at an operating voltage of 1 V than the direct borohydride-hydrogen peroxide fuel cell with carbon-supported Prussian Blue without CTAB with the maximum output power density of 29 mW cm−2 at an operating voltage of 1 V.

The gas-diffusion layer (GDL) influences the performance of electrodes employed with polymer electrolyte fuel cells (PEFCs). A simple and effective method for incorporating a porous structure in the electrode GDL using sucrose as the pore former is reported. Optimal (50 w/o) incorporation of a pore former in the electrode GDL facilitates the access of the gaseous reactants to the catalyst sites and improves the fuel cell performance. Data obtained from permeability and porosity measurements, single-cell performance, and impedance spectroscopy suggest that an optimal porosity helps mitigating mass-polarization losses in the fuel cell resulting in a substantially enhanced performance.

Incorporation of silica particles through a sol-gel process into the anode-catalyst layer with a sol-gel modified Nafion-silica composite membrane renders easy retention of back-diffused water from the cathode to anode through the composite membrane electrolyte, increases the catalyst-layer wettability and improves the performance of the Polymer Electrolyte Fuel Cell (PEFC) while operating under relative humidity (RH) values ranging between 18% and 100% with gaseous hydrogen and oxygen reactants at atmospheric pressure. A peak power density of 300 mW cm−2 is achieved at a load current-density value of 1200 mA cm−2 for the PEFC employing a sol-gel modified Nafion-silica composite membrane and operating at 18% RH. Under similar operating conditions, the PEFC with a Membrane Electrode Assembly (MEA) comprising Nafion-silica composite membrane with silica in the anode-catalyst layer delivers a peak power density of 375 mW cm−2. By comparison, the PEFC employing commercial Nafion membrane fails to deliver satisfactory performance at 18% RH due to the limited availability of water at its anode, acerbated electro-osmotic drag of water from anode to cathode and insufficient water back diffusion from cathode to anode causing the MEA to dehydrate.

A method, to anchor phenyl-sulfonic acid functional groups with the platinum catalyst supported onto a high surface-area carbon substrate, is reported. The use of the catalyst in the electrodes of a polymer electrolyte fuel cell (PEFC) helps enhancing its performance. Characterization of the catalyst by Fourier transform infra red (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and point-of-zero-charge (PZC) studies suggests that the improvement in performance of the PEFC is facilitated not only by enlarging the three-phase boundary in the catalyst layer but also by providing ionic-conduction paths as well as by imparting negative charge to platinum sites with concomitant oxidation of sulfur present in the carbon support. It is argued that the negatively charged platinum sites help repel water facilitating oxygen to access the catalyst sites. The PEFC with modified carbon-supported platinum catalyst electrodes exhibits 40% enhancement in its power density as compared to the one with unmodified carbon-supported platinum catalyst electrodes.

Longevity remains as one of the central issues in the successful commercialization of polymer electrolyte membrane fuel cells (PEMFCs) and primarily hinges on the durability of the cathode. Incorporation of gold (Au) to platinum (Pt) is known to ameliorate both the electrocatalytic activity and stability of cathode in relation to pristine Pt-cathodes that are currently being used in PEMFCs. In this study, an accelerated stress test (AST) is conducted to simulate prolonged fuel-cell operating conditions by potential cycling the carbon-supported Pt–Au (Pt–Au/C) cathode. The loss in performance of PEMFC with Pt–Au/C cathode is found to be ∼10% after 7000 accelerated potential-cycles as against ∼60% for Pt/C cathode under similar conditions. These data are in conformity with the electrochemical surface-area values. PEMFC with Pt–Au/C cathode can withstand >10 000 potential cycles with very little effect on its performance. X-ray diffraction and transmission electron microscopy studies on the catalyst before and after AST suggest that incorporating Au with Pt helps mitigate aggregation of Pt particles during prolonged fuel-cell operations while X-ray photoelectron spectroscopy reflects that the metallic nature of Pt is retained in the Pt–Au catalyst during AST in comparison to Pt/C that shows a major portion of Pt to be present as oxidic platinum. Field-emission scanning electron microscopy conducted on the membrane electrode assembly before and after AST suggests that incorporating Au with Pt helps mitigating deformations in the catalyst layer.

Carbon-supported Pt-TiO2 (Pt-TiO2/C) catalyst with varying atomic ratio of Pt to Ti, namely, 1: 1, 2: 1, and 3: 1, is prepared by sol-gel method and its electrocatalytic activity toward oxygen-reduction reaction (ORR) is evaluated for the application in polymer electrolyte fuel cells (PEFCs). The optimum atomic ratio of Pt to Ti in Pt-TiO2/C and annealing temperature are established by cyclic voltammetry and fuel-cell-polarization studies. Pt-TiO2/C annealed at 750 degrees C with Pt and Ti in atomic ratio of 2: 1, namely, 750 Pt-TiO2/C (2: 1), shows enhanced electrocatalytic activity toward ORR. It is found that the incorporation of TiO2 with Pt ameliorates both electrocatalytic activity and stability of cathode in relation to pristine Pt cathode, currently being used in PEFCs. A power density of 0.75 W/cm(2) is achieved at 0.6 V for the PEFC with 750 Pt-TiO2/C (2: 1) as compared with 0.62 W/cm(2) at 0.6 V achieved with the PEFC comprising Pt/C as cathode catalyst while operating under identical conditions. Interestingly, carbon-supported Pt-TiO2 cathode exhibits only 6% loss in electrochemical surface area after 5000 potential cycles while it is as high as 25% for Pt/C. DOI: 10.1115/1.4002466]

Durability is central to the commercialization of polymer electrolyte fuel cells (PEFCs). The incorporation of TiO2 with platinum (Pt) ameliorates both the stability and catalytic activity of cathodes in relation to pristine Pt cathodes currently being used in PEFCs. PEFC cathodes comprising carbon-supported Pt-TiO2 (Pt-TiO2/C) exhibit higher durability in relation to Pt/C cathodes as evidenced by cell polarization, impedance, and cyclic voltammetry data. The degradation in performance of the Pt-TiO2/C cathodes is 10% after 5000 test cycles as against 28% for Pt/C cathodes. These data are in conformity with the electrochemical surface area and impedance values. Pt-TiO2/C cathodes can withstand even 10,000 test cycles with nominal effect on their performance. X-ray diffraction, transmission electron microscope, and cross-sectional field-emission-scanning electron microscope studies on the catalytic electrodes reflect that incorporating TiO2 with Pt helps in mitigating the aggregation of Pt particles and protects the Nafion membrane against peroxide radicals formed during the cathodic reduction of oxygen. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3421970] All rights reserved.

Carbon-supported Pt-TiO2 (Pt-TiO2/C) catalysts with varying at. wt ratios of Pt to Ti, namely, 1:1, 2:1, and 3:1, are prepared by the sol-gel method. The electrocatalytic activity of the catalysts toward oxygen reduction reaction (ORR), both in the presence and absence of methanol, is evaluated for application in direct methanol fuel cells (DMFCs). The optimum at. wt ratio of Pt to Ti in Pt-TiO2/C is established by fuel cell polarization, linear sweep voltammetry, and cyclic voltammetry studies. Pt-TiO2/C heattreated at 750 degrees C with Pt and Ti in an at. wt ratio of 2:1 shows enhanced methanol tolerance, while maintaining high catalytic activity toward ORR. The DMFC with a Pt-TiO2/C cathode catalyst exhibits an enhanced peak power density of 180 mW/cm(2) in contrast to the 80 mW/cm(2) achieved from the DMFC with carbon-supported Pt catalyst while operating under identical conditions. Complementary data on the influence of TiO2 on the crystallinity of Pt, surface morphology, and particle size, surface oxidation states of individual constituents, and bulk and surface compositions are also obtained by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive analysis by X-ray, and inductively coupled plasm optical emission spectrometry.

Hydrous ruthenium oxide, which exhibits both protonic and electronic conduction, is incorporated in the cathode electrocatalyst layer of the membrane electrode assembly for polymer electrolyte fuel cells (PEFCs). The supercapacitive behavior of ruthenium oxide helps realize a fuel cell–supercapacitor hybrid. Platinum (Pt) nanoparticles are deposited onto carbon-supported hydrous ruthenium oxide and the resulting electrocatalyst is subjected to both physical and electrochemical characterization. Powder X-ray diffraction and transmission electron microscopy reflect the hydrous ruthenium oxide to be amorphous and well-dispersed onto the catalyst. X-ray photoelectron spectroscopy data confirm that the oxidation state of ruthenium in Pt anchored on carbon-supported hydrous ruthenium oxide is Ru4+. Electrochemical studies, namely cyclic voltammetry, cell polarization, intrinsic proton conductivity, and impedance measurements, suggest that the proton-conducting nature of hydrous ruthenium oxide helps extend the three-phase boundary in the catalyst layer, which facilitates improvement in performance of the PEFC. The aforesaid PEFC operating with hydrogen fuel and oxygen as oxidant shows a higher power density (0.62 W/cm2 @ 0.6 V) in relation to the PEFC comprising carbon-supported Pt electrodes (0.4 W/cm2 @ 0.6 V). Potential square-wave voltammetry study corroborates that the supercapacitive behavior of hydrous ruthenium oxide helps ameliorate the pulse-power output of the fuel cell.

Nafion-silica composite membranes are fabricated by embedding silica particles as inorganic fillers in perfluorosulfonic acid ionomer by a novel water hydrolysis process. The process precludes the use of an added acid but exploits the acidic characteristic of Nafion facilitating an in situ polymerization reaction through a sol-gel route. The use of Nafion as acid helps in forming silica/siloxane polymer within the membrane. The inorganic filler materials have high affinity to water and assist proton transport across the electrolyte membrane of the polymer electrolyte fuel cell (PEFC) even under low relative humidity (RH) conditions. In the present study, composite membranes have been tested in hydrogen/oxygen PEFCs at varying RH between 100 and 18% at elevated temperatures. Attenuated total reflectance-Fourier transform infrared spectroscopy and scanning electron microscopy studies suggest an evenly distributed siloxane polymer with Si-OH and Si-O-Si network structures in the composite membrane. At the operational cell voltage of 0.4 V, the PEFC with an optimized silica-Nafion composite membrane delivers a peak power density value five times higher than that achievable with a PEFC with conventional Nafion-1135 membrane electrolyte while operating at a RH of 18% at atmospheric pressures.