Photoelectrocatalytic oxidation of ascorbate promoted by glucose and tris-(hydroxylmethyl)-amino methane on cadmium sulfide/titanium dioxide electrodes for efficient visible light-enhanced fuel cells

Abstract

Glucose (GLU) and tris-(hydroxylmethyl)-amino methane (Tris) have been introduced to promote the photoelectrocatalytic oxidation of ascorbate (AA) on binary CdS-TiO2 nanoparticle-modified electrodes for efficient photoelectrochemical fuel cells. The oxidative peak height of AA shows an increase with the rise of AA, GLU, OH− or Tris concentration under dark or visible light irradiation conditions. The photoelectrocatalytic activities of TiO2 nanoparticles are dependent on the calcination temperature ranged between 250 and 850 °C. The TiO2-450 generated from the calcination treatment at 450 °C is combined with CdS nanoparticles to achieve a CdS/TiO2-450 electrode with high photoelectrocatalytic activity towards the oxidation of AA and GLU, for which the oxidation mechanism is discussed. While employing CdS/TiO2-450 as anode, carbon felt (CF) as cathode, 0.1 mol L−1 AA-0.1 mol L−1 GLU as fuels, Na2SO3-Na2S as sulfur-containing sacrificial agents, and 60 mL min−1 O2 as oxidant, the visible light-assisted fuel cell shows synergistically enhanced performances. The open-circuit photovoltage (VOC) and short-circuit photocurrent density (ISC) are 0.813 V and 0.568 mA cm−2, and the maximum power density (Pmax) is 35.56 μW cm−2 upon visible light irradiation of 0.18 mW cm−2. The present results provide an interesting platform for the effective utilization of renewable energy sources.