Surfactant-assisted formation of silver titanates as active catalysts for methanol electro-oxidation

Abstract

Silver nanoparticles successfully incorporated in titanate nanosheets and synthesized hydrothermally via employing cetyltrimethylammonium bromide (CTAB) and triblock copolymer (pluronic F127) assisted templates were thoroughly characterized using transmission electron microscopy-selected area electron diffraction (TEM-SAED), X-ray diffraction, diffuse reflectance UV/visible absorption spectroscopy, N2 sorptiometry, FTIR and Raman spectroscopy. The dispersed Ag nanoparticles of uniform size (2–3nm) were found to contact intimately with titanateF127 nanosheets to show superior crystallinity, wider layer distances and higher surface area and pore volume (SBET=51.1m2g−1,Vp=0.081cm3g−1) than Ag/titanateCTAB (7.2m2g−1, 0.02cm3g−1). This constructed Ag/titanateF127 exhibits markedly improved electrocatalytic (1.4-fold) and photoelectrocatalytic (4.0-fold) activities and stabilities towards methanol oxidation than that of Ag/titanateCTAB; as determined using cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The enhanced activity of Ag/titanateF127 was also attributed to electron transfer across the interface potential of the composite Ag-titanateF127 as well as the delay of charge recombination that has been substantiated not only via exposed Ag but also through the non-decomposed carbon template. This enhanced electron transfer and electronic conductivity was established by impedance spectroscopy, and exhibits the maximum obtained photocurrent density (2.0mAcm−2) under visible light illumination (λ>420nm, 88W). The results revealed that the template F127 had a significant effect not only on enhancing the titanate crystallinity and exhibiting a surface plasmon resonance band; unlike Ag/titanateCTAB, but also in acquiring a high pore volume value and widened layers, which all work towards improving the Ag-titanateF127 durability for methanol oxidation.