Controlled Synthesis of Vertically Aligned Hematite on Conducting Substrate for Photoelectrochemical Cells: Nanorods versus Nanotubes

Abstract

This paper describes two different processes to synthesize vertically aligned hematite nanorod and nanotube arrays, respectively, on a conductive substrate by the electrochemical deposition method with the help of an anodized aluminum oxide nanotemplate. The two types of nanostructured hematite were used as the photoanode for photoelectrochemical cells. The hematite nanotubes exhibited much higher photoelectrochemical activity than the hematite nanorods, including an improved photocurrent density, more negative onset potential, better photon harvesting, and better charge carrier transfer ability. The observed behavior may offer new information to enhance the photocatalytic ability of hematite, which is considered to be one of the best photoanode materials in the research field of photoelectrochemical cells.

Enhanced photoelectrochemical water-splitting performance of semiconductors by surface passivation layers

“…Some commonly used strategies to improve the overall solarto-hydrogen efficiency in PEC devices include: (1) increasing the photocurrent by engineering the semiconductor absorber layer morphology to yield better light absorption; [14][15][16][17][18][19][20][21][22] (2) improving charge-carrier transfer and collection efficiency by micro-or nanostructuring the semiconductor;…”

Cobalt Phosphate Group Modified Hematite Nanorod Array as Photoanode for Efficient Solar Water Splitting

“…As known to all, the band gap of most nanorod/nanowire materials is too large to efficiently harvesting the solar energy, leading to undesirable photoelectrochemical efficiency. Various strategies have been applied to prepare the hematite nanorod, for example, the thermal oxidization, template synthesis through anodic aluminum oxide (AAO) [18], and hydrothermal deposition [5]. Among these methods, hydrothermal deposition is a facile and adoptable method to prepare hematite nanorod arrays.…”

Application of Conducting Polymers in Solar Water-Splitting Catalysis

“…Mao et al [63] reported that PANI may improve photocatalytic water splitting by enhancing the morphology of a PEC. Their design employed n-type hematite (α-Fe 2 O 3 ), which has a bandgap of 2.0-2.2 eV, allowing 40 % of incident light to be absorbed with improved photochemical stability at pH < 3.…”

“…In the second route, electrodeposition using an aqueous solution of KAu(CN) 2 and KH 2 PO 4 allowed Au to be electrodeposited into the AAO pores, where α-Fe 2 O 3 was deposited later as nanorods. Both the nanotubes and [63] nanorods were tested as photoanodes for water oxidation. The hematite nanotubes displayed greater photoelectrochemical activity than the hematite nanorods.…”