Increase in Photocurrent Density of WO3 Photoanode by Placing a Layer of an Ordered Array of Mesoporous WO3 Micropillars on Top of a WO3 Sheet Layer

Sarnai Puntsagdorj; Agni Raj Koirala; Jargalsaikhan Gombovanjil; Nguyen Nguyen Khanh; Sang Do Sung; Wan In Lee; Kyung Byung Yoon

doi:10.1021/acsami.2c05107

Increase in Photocurrent Density of WO₃ Photoanode by Placing a Layer of an Ordered Array of Mesoporous WO₃ Micropillars on Top of a WO₃ Sheet Layer

ACS Appl Mater Interfaces. 2022 Jul 20;14(28):31838-31850. doi: 10.1021/acsami.2c05107. Epub 2022 Jul 6.

Authors

Sarnai Puntsagdorj¹, Agni Raj Koirala¹, Jargalsaikhan Gombovanjil¹, Nguyen Nguyen Khanh¹, Sang Do Sung², Wan In Lee², Kyung Byung Yoon¹

Affiliations

¹ Department of Chemistry, Sogang University, Seoul 04107, Korea.
² Department of Chemistry, Inha University, 100 Inharo, Nam-gu, Incheon 22212, Korea.

PMID: 35792885
DOI: 10.1021/acsami.2c05107

Abstract

A facile stamping method was developed to assemble ordered arrays of mesoporous WO₃ micropillars with uniform sizes, shapes, and lengths on F-doped tin oxide glass. Using this method, a series of WO₃ heterostructural bilayer photoanodes consisting of an array of m-μm long ordered mesoporous WO₃ micropillars at the top and the n-μm thick mesoporous WO₃ plain sheet layer at the bottom (denoted as m/n) were prepared. Among them 2.5/7.5 displayed a steady state photocurrent density of 3.6 mA cm^-2 at 1.23 V (vs RHE) under AM 1.5 (1 Sun), which is much higher than that of the plain 10-μm thick WO₃ sheet (2.5 mA cm^-2). This phenomenon occurs owing to the following six benefits: increases in charge carrier density, number of photogenerated electron, charge collection rate, thermodynamic feasibility for the vectorial charge transport from the outermost layer of the photoanode to the inner layer, the surface hydrophilicity, and the decrease in charge transfer resistance.

Keywords: carrier density increase; charge collection rate increase; charge transfer resistance decrease; higher surface hydrophilicity; photoelectrochemical water splitting; vectorial charge transfer.