1. Hexamethylenetetramine concentration effect on CaWO4 for electrochemical hydrogen evolution reaction activity.
- Author
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Swathi, S., Yuvakkumar, R., Senthil Kumar, P., Ravi, G., and Velauthapillai, Dhayalan
- Subjects
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METHENAMINE , *OXYGEN evolution reactions , *HYDROGEN evolution reactions , *CATALYSTS , *BAND gaps , *UNIT cell , *SCANNING electron microscopy , *CHARGE transfer - Abstract
[Display omitted] • CW1, CW2 and CW3 electrodes overpotential were 123, 115 and 102 mV. • Tafel slope values of prepared electrodes were 245, 244 and 238 mV/dec. • CW3 electrode exhibited high C dl value of 32.8 mF/cm2 and enhanced HER. • CW3 electrode exhibited 75% retention in 16 h durability test. Hexamethylenetetramine (HMT) assisted calcium tungstate nanostructures were successfully synthesized through co-precipitation method. The phase and material confirmation of scheelite type calcium tungstate nanostructures with tetragonal unit cell (a = 5.193 and c = 11.255) were done by employing X-ray diffraction (XRD). All the prepared electrocatalysts such as CW1, CW2 and CW3 crystallite sizes were 29.01, 24.86 and 17.40 nm respectively. The calculated band gap values were found to be 3.31, 3.31 and 3.27 eV for CW1, CW2 and CW3 materials respectively. Different morphology such as ball like and dumbbell shaped calcium tungstate were revealed by scanning electron microscopy (SEM). Surfactant largely plays a significant role to reduce nanostructures agglomeration. The specific surface area, pore volume and diameter of 0.1 M hexamethylenetetramine (HMT) assisted calcium tungstate nanostructure was about 24.7 m2/g, 0.141 cc/g and 3.365 nm. The surface area of the calcium tungstate nanostructures drastically enhanced hydrogen evolution reaction (HER) performance as recognized by linear sweep voltammetry. The overpotential values of CW1, CW2 and CW3 electrodes were 123, 115 and 102 mV respectively. Solution resistance (R s) and charge transfer resistance (R ct) of synthesized materials was finding out by electrochemical impedance spectroscopy and all prepared electrocatalyst estimated values were 1.07, 1.25, 1.34 Ω and 4.06, 1.62, 0.76 Ω respectively. The stability of 0.1 M hexamethylenetetramine (HMT) assisted CaWO 4 was analyzed by 16 h and it exhibited excellent robustness without any decay. The synthesized CaWO 4 material exhibited superior hydrogen evolution reaction (HER) activity and the prepared electrodes was capable electro catalysts in water splitting applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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