Carbon-Coated Hematite Electrodes with Enhanced Photoelectrochemical Performance Obtained through an Electrodeposition Method with a Citric Acid Additive

摘要

In this study, carbon-coated hematite electrodes exhibiting high photoelectrochemical (PEC) performance with a photocurrent density of 2.1 mA cm(-2) at 0.4 V versus SCE were obtained by using a simple electrodeposition method with an electrolyte containing citric acid additives. This achievement is attributed to the high affinity of citric acid to iron oxide, which allows the bound citric acid residing in the porous hematite films to develop a carbon layer in the subsequent sintering process. The passivation effect resulting from the surface carbon layer is likely responsible for the observed high PEC performance. Importantly, the oxidation of the surface carbon layer would, on the other hand, reduce the surface of hematite to FeOOH, which deteriorates the photocurrent density by approximately one order of magnitude. Accordingly, the manipulation of a good carbon layer on the surface of hematite would be an important issue to further improve the PEC performance of hematite electrodes.