Photoelectrochemical Performance Dependence on Geometric Surface Area of Branched ZnO Nanowires

Abstract

Nanoarray architectures beneficial for a large electrochemically active surface area, intense light adsorption, and fast charge transport have attracted increasing attention in the past few years as enhanced catalysts for photoelectrochemical water splitting. However, the correlation between architecture and optical/electrochemical properties are not fully understood yet. Here a hierarchically branched ZnO nanowire structure is used as an example to investigate the effect of its geometry on light absorption and electrochemically active surface area. We used a two‐step hydrothermal method to synthesize the ZnO branched nanowires grown on fluorine doped tin oxide (FTO) coated glasses. The branch size of the ZnO nanowires was adjusted by changing the hydrothermal parameters. The relationship between the geometric surface area and light absorption spectra as well as electrochemically active surface area were compared. It was found that with increase of geometric surface area the electrochemically active surface area increases monotonically but the light absorption first increased but then decreased. The monotone increase of the photoelectrochemical activity indicates that the large surface area facilitating the hole transfer reaction at the ZnO/electrolyte interface is profound to improve its photon‐to‐current conversion efficiency.

Architecture lattice‐matched cauliflower‐like CuO/ZnO p–n heterojunction toward efficient water splitting

“…ZnO is a commonly accepted n-type semiconductor PEC catalyst for its nontoxicity, stability, high electron mobility, easy availability and low manufacturing cost. 24,25 The heterojunction of ZnO and CuO could benefit greatly from suitable built-in field potentials and enhanced photovoltage to prevent or mitigate corrosion. [26][27][28][29][30] Furthermore, the lattice-matched heterogeneous interface of ZnO and CuO could consolidate the synergistic effects via decreasing the interfacial contact resistance, optimizing the interfacial transmission path and rebuilding active reaction sites.…”

Nesting BiVO4 nanoislands in ZnO nanodendrites by two-step electrodeposition for efficient solar water splitting

“…ZnO nanodendrites (NDs) included in this class of nanostructures are very promising candidate for solar energy conversion applications due to their low-cost and a facile synthesis process. In contrast to the conventional methods in which 3D ZnO NDs are grown over sequentially reseeded ZnO NRs surface in aqueous phase [15][16][17], Wu et al purposed an alternative fabrication method utilizing a supersaturated solution without any sequential seed layer or organic structure-directing agent [18]. Nevertheless, besides all other assets, a wide band gap (∼3.2 eV) of ZnO is considered as the fundamental obstacle to achieving moderate STH efficiency via its utilization in the PEC water splitting.…”

Photoconversion efficiency of In2S3/ZnO core-shell heterostructures nanorod arrays deposited via controlled SILAR cycles

“…Several strategies have been adopted to improve the optical absorbance and PCE of ZnO which include nanostructure optimization [18], doping [19], sensitization [20], and so forth [21]. For improving the solar light usage and enabling the photon-generated carriers separation, fabrication of the semiconductor heterojunctions with low band gap energies are an efficient way [22,23].…”