Highly Efficient Photoelectrochemical Hydrogen Generation Using Hierarchical ZnO/WO_x Nanowires Cosensitized with CdSe/CdS

Abstract

A photoelectrochemical device with a novel hierarchical heterostructure coupled with narrow bandgap semiconductors is demonstrated for efficient hydrogen generation via water splitting. The heterostructures consist of ZnO nanowire branches grown on WO x nanowhisker stems, which offer a large surface area and efficient charge transport path. The assembly of CdSe/CdS narrow bandgap cosensitizers on hierarchical ZnO/WO x nanostructures is shown to enhance light harvesting in the visible light region. The cosensitized ZnO/WO x heterostructures demonstrate efficient light absorption up to a wavelength of 800 nm as well as enhanced photoelectrochemical properties when used as photoanodes. Furthermore, CdSe/CdS cosensitized ZnO/WO x has a type II cascade band structure, resulting in efficient charge transport, which was confirmed by open circuit voltage decay measurements. Our photoelectrochemical system produced a high photocurrent density of 11 mA/cm2 at −0.5 V (vs SCE) under 1.5 AM irradiation for hydrogen generation.

The structural and the photoelectrochemical properties of ZnO–ZnS/ITO 1D hetero-junctions prepared by tandem electrodeposition and surface sulfidation: on the material processing limits

“…It should be noted that atband potential of these hybrids is lower than that of the parent material, meaning that the energy barrier is lower in heterojunctioned ZnO NRs than in pure ones. 29,30 When the applied bias potential is increased, J p increases, the highest values being reached at V ¼ 0.6 V.…”

Strongly Coupled Nafion Molecules and Ordered Porous CdS Networks for Enhanced Visible‐Light Photoelectrochemical Hydrogen Evolution

“…Detailed spectroscopic Photoelectrochemical (PEC) water splitting, using sunlight to produce hydrogen, is a clean, renewable and environmentalbenign strategy for solar fuel production. [1][2][3][4][5][6][7][8][9][10][11][12] Semiconductor photoelectrodes play key roles in PEC hydrogen evolution, and 3D nanostructured photoelectrodes with large surface area, such as nanowire/nanorod arrays [13][14][15][16][17][18] and inverse opal (IO) networks, [19][20][21][22][23][24] have been widely studied owing to their advantageous light trapping and absorption, fast charge separation, and transfer capabilities. However, to date the conversion efficiencies of these photoelectrodes remain relatively low, [ 25 ] a fact mainly attributed to serious surface recombination losses resulting from large 3D nanostructure/electrolyte interface with a high density of surface defects.…”

A ternary g-C 3 N 4 /Pt/ZnO photoanode for efficient photoelectrochemical water splitting

“…However, ZnO has a large band gap, 3.2 eV, so that it absorbs only the ultraviolet (UV) part of the solar spectrum. This intrinsic property restricts the application of ZnO in photocatalysis [5]. Two approaches are often used to improve the photoelectrochemical (PEC) performance of the photocatalysts.…”