A Synergistic Effect of Surfactant and ZrO(2) Underlayer on Photocurrent Enhancement and Cathodic Shift of Nanoporous Fe(2)O(3) Photoanode

Augmenting the donor density and nanostructure engineering are the crucial points to improve solar water oxidation performance of hematite (α-Fe(2)O(3)). This work addresses the sluggish water oxidation reaction associated with hematite photoanode by tweaking its internal porosity. The porous hematite photoanodes are fabricated by a novel synthetic strategy via pulse reverse electrodeposition (PRED) method that involves incorporation of a cationic CTAB surfactant in a sulfate electrolyte and spin-coated ZrO(2) underlayer (UL) on FTO. CTAB is found to be beneficial in promoting the film growth rate during PRED. Incorporation of Zr(4+) ions from ZrO(2) UL and Sn(4+) ions from FTO into the Fe(2)O(3) lattice via solid-state diffusion reaction during pertinent annihilation of surfactant molecules at 800 °C produced internally porous hematite films with improved carrier concentration. The porous hematite demonstrated a sustained photocurrent enhancement and a significant cathodic shift of 130 mV relative to the planar hematite under standard illumination conditions (AM 1.5G) in 1 M NaOH electrolyte. The absorption, electrochemical impedance spectroscopy and Mott-Schottky analyses revealed that the ZrO(2) UL and CTAB not only increased the carrier density and light harvesting but also accelerated the surface oxidation reaction kinetics, synergistically boosting the performance of internally porous hematite photoanodes.