Abstract
An ultrathin FeOOH cocatalyst is deposited on α-Fe2O3 photoanodes in a simple room temperature immersion process for efficient photoelectrochemical (PEC) water splitting. The prepared FeOOH/Fe2O3 photoanode has a photocurrent density of up to 2.4 mA/cm2 at 1.23 V versus reversible hydrogen electrode (RHE), and the photocurrent density is increased by about 160% compared to the bare Fe2O3 of 1.55 mA/cm2. An obvious cathodic shift of the photocurrent onset potential from 0.661 to 0.582 V was also observed, and excellent stability was maintained with almost no deterioration for 5 h. The enhanced PEC performance is attributed to the decrease of the interfacial resistance between electrode and electrolyte and the increase of the injection efficiency of holes in Fe2O3.
Highlights
Solar-driven photoelectrochemical (PEC) water splitting has been a promising method to translate solar energy to chemical fuels, which has been widely concerned and studied [1]
FeOOH/Fe2O3 photoanodes were formed by the room temperature impregnation method
The Fe2O3 photoanode was immersed in 25 ml solution of 0.075 M FeCl3·6H2O (Shanghai Hushi, 99.99%) and 0.15 M CO(NH2)2 (Shanghai Hushi, 99%) for varying durations (1 h, 2 h, and 3 h) at room temperature (25°C)
Summary
Solar-driven photoelectrochemical (PEC) water splitting has been a promising method to translate solar energy to chemical fuels, which has been widely concerned and studied [1]. As a promising candidate material for PEC water splitting, α-Fe2O3 has advantages such as excellent stability, economical, nontoxic, appropriate band gap (~2.1 eV), high theoretical photocurrent value of 12.5 mA/cm, and nearly 15.8% solar-to-hydrogen efficiency (STH) [9]. OEC deposition can effectively accelerate the oxidation rate of water, thereby reducing the onset potential of α-Fe2O3. The formed FeOOH cocatalyst effectively decreases the interfacial resistance between the electrode and the electrolyte of Fe2O3 photoanodes and increases the injection efficiency of holes. This allows the holes to travel faster from the Fe2O3 photoanode surface to the electrolyte, the efficient water oxidation reaction occurs at the interface of electrode and electrolyte. A cathodic shift of onset potential is about 80 mV from 0.66 to 0.58 V and excellent photostability in 5 h
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