RESUMEN
Formic acid (HCOOH) has attracted much attention as a promising power source for portable electronic devices because of its ease of storage and transportation. Here we report that a simple HCOOH photo-fuel cell (PFC) consisting of mesoporous anatase TiO2 photoanode and Pt cathode stably delivers a short-circuit photocurrent (Jsc) of 5.94 mA cm-2 and an open-circuit voltage of 0.94 V under UV-light irradiation (light intensity, I = 200 mW cm-2). The incident photon-to-current conversion efficiency and Faradaic efficiency reach ~90% and ~100%, respectively. The excellent performances of this HCOOH PFC, designed based on the discovery that HCOOH provides a large photocurrent by current doubling even in the presence of O2, not only solves the problem of conventional HCOOH FCs, but also achieves the performances far exceeding those of PFCs using biomass-derived organics reported so far.
RESUMEN
Removal of recalcitrant pollutants from water is a major challenge, to which the photoelectrocatalytic processes may be a solution. Applied potential plays a key role in the photocatalytic activity of the semiconductor. This paper investigated the effect of applied potential on the photoelectrocatalytic oxidation of 2,4-Dichlorophenoxyacetic acid (2,4-D) with TiO2 nanotubular anodes under solar light irradiation. The process was investigated at constant potentials in different regions of the polarization curve: the ohmic region, the saturation region and in the region of the Schottky barrier breakdown. PEC tests were performed in aqueous solutions of 2,4-D, and in the presence of methanol or formic acid, as scavengers of OH⢠radicals and holes. Results showed the main mechanism is oxidation by OH⢠radicals from water oxidation, while runs with hole scavenger revealed a second mechanism of direct oxidation by holes photogenerated at the electrode surface, with high removal rates due to current doubling effect.