Tungsten carbide (WC) has been explored
as a cost-effective
and
Earth-abundant alternative electrocatalyst for the hydrogen evolution
reaction (HER) in both acid and alkaline conditions, due to its electronic
structure comparable to that of platinum. Herein, we report on a simple
and convenient approach for depositing the carbon-embedded WC electrocatalyst
on nickel foam from the thermal reduction of a sucrose-impregnated
self-deposited tungsten trioxide (WO3) precursor. Different
sucrose concentrations (between 20 and 80% aqueous solution) and reduction
temperatures (between 600 and 1000 °C) are tested to achieve
an optimized material exhibiting the best electrocatalytic efficiency
for HER. The optimized material is obtained from the precursor impregnated
with 50% sucrose and thermally reduced at 800 °C. It can operate
HER with overpotential values measured at 10 and 100 mA cm–2 of 0.124 and 0.232 V, respectively, at pH 14, and 0.208 and 0.333
V at pH 0.3, respectively. Furthermore, these electrodes are found
to be stable in both media during controlled-current density electrolysis
tests over a period of 40 h. The presence of excess amorphous carbon
embedding WC is beneficial to improve the conductivity and dispersibility
of the electrocatalyst and consequently its HER activity. These findings
demonstrate that robust and efficient WC-based binder-free HER electrocatalysts
can be produced easily from spontaneously deposited WO3 film and sucrose as the carbon source.
type microporous silico alumino phosphate SAPO-35 are synthesized by using hydrothermal method. TiO 2 /SAPO-35 nanocomposites were prepared by solgel method with different weight ratios. The synthesized materials were characterized by various analytical techniques such as PXRD, SEM/EDAX, TG/DTA, BET-Surface area, FT-IR, UV-Vis, XPS, MAS-NMR and photocatalytic study. From PXRD results it clearly evidenced that, the TiO 2 anatase peaks and SAPO-35 combined peaks are in the composite. The spherical shaped TiO 2 nanoparticles were found to be dispersed over the rhombohedral SAPO-35 particles, which was analysed by SEM. BET-surface area analysis revealed that, the calcined SAPO-35 has the surface area of 448 m 2 /g, was decreased to 222 m 2 /g for composite which is due to the presence of TiO 2 particles having surface area of 85 m 2 /g on the surface of SAPO-35. The oxidation state and co-ordination of various elements present in nanocomposite was composed by X-ray photoelectron spectroscopy. MAS-NMR analysis has shown that SAPO-35 has tetrahedral Al, P and Si oxides. Eventhough Al is unique Si and P are in two different environment namely one in S6R and another in D6R with double intensity. The photocatalytic performance of methylene blue degradation under sunlight radiation by the synthesized TiO 2 /SAPO-35 was analyzed. The TiO 2 /SAPO-35 composites degrade the methylene blue under sunlight irradiation in 25 minutes against 90 minuts for pure TiO 2 anatase. A plausible mechanism on photocatalytic activity is also proposed.
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