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

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, N 2 sorptiometry, FTIR and Raman spectroscopy. The dispersed Ag nanoparticles of uniform size (2–3 nm) were found to contact intimately with titanate F127 nanosheets to show superior crystallinity, wider layer distances and higher surface area and pore volume (S BET = 51.1 m 2 g −1 , V p = 0.081 cm 3 g −1 ) than Ag/titanate CTAB (7.2 m 2 g −1 , 0.02 cm 3 g −1 ). This constructed Ag/titanate F127 exhibits markedly improved electrocatalytic (1.4-fold) and photoelectrocatalytic (4.0-fold) activities and stabilities towards methanol oxidation than that of Ag/titanate CTAB ; as determined using cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The enhanced activity of Ag/titanate F127 was also attributed to electron transfer across the interface potential of the composite Ag-titanate F127 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 (2.0 mA cm −2 ) under visible light illumination (λ > 420 nm, 88 W). 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/titanate CTAB , but also in acquiring a high pore volume value and widened layers, which all work towards improving the Ag-titanate F127 durability for methanol oxidation.