TiO₂/Au Nanoring/p-Si Nanohole Photocathode for Hydrogen Generation

Abstract

Nowadays, numerous electrochemical and photoelectrochemical (PEC) methods have been utilized for water-splitting hydrogen production. Herein, we designed a novel photocathode based on a TiO2/Au nanoring (AuNR)/Si nanohole (SiNH) hetero-nanostructure (HN), which can be fabricated in a programmable way. The SiNH arrays substrate was prepared by nanoimprint lithography, and then, embedded AuNRs were fabricated by sputtering deposition and subsequent ion beam etching to remove the Au layer covering the horizontal Si surface. Cylindrical AuNRs clinging to the sidewalls of SiNH arrays could maximize the horizontal exposure area of the Si substrate and have little adverse effect on its light absorption. The design is supported by theory simulation and could lead to expectable PEC performance by precisely controlling the geometry and size of the AuNR which will trigger localized surface plasmon resonance (LSPR), bringing about a prominent enhancement of the light harvesting ability and exciting vast hot electrons under light illumination. Generated electrons could transfer across the Schottky junction formed by AuNR and TiO2 to contribute to the hydrogen evolution reaction (HER). The excellent hydrogen production performance with an onset potential of 0.32 VRHE of our prepared HN electrode could be attributed to the synergetic effect of an electrochemical and PEC process, and the maximum photon-to-energy conversion efficiency reaches 13.3%. The experimental results are in good accordance with the simulation analysis and demonstrate an enhancement of the catalytic performance by optimizing the sizes of those components. This work may provide a new path to boost hydrogen production performance by designing customized HNs with a positive effect for electrocatalysis or photoelectrocatalysis.

Antibacterial Activity of Graphene Oxide/g-C3N4 Composite through Photocatalytic Disinfection under Visible Light

“…Nanoscale materials have sprung up as innovative antimicrobial agents because of their unique chemical and physical properties. Up to now, TiO 2 , 3 ZnO, MgO, Al 2 O 3 , AgNPs, 4,5 and carbon-based nanomaterials 6−8 (GO, rGO, SWCNT, C60, MWCNT) have been reported to display antibacterial activity to some extent, and among them, TiO 2 has attracted wide attention in the photocatalysis field. However, pure TiO 2 is not an ideal photocatalyst due to its limitations in the excitation wavelength of ultraviolet band, implying that it can not make full use of solar light.…”

Surface/Interface Engineering of Si-Based Photocathodes for Efficient Hydrogen Evolution

“…Electric field (| E / E 0 |) distributions simulated by COMSOL Multiphysics: (a) cross view perpendicular to the direction of the electric field and (b) top view of the interface between the Si surface and the TiO 2 layer. Reprinted with permission from ref . Copyright 2019 American Chemical Society.…”

“…In addition, noble metals (such as Pt or Au) were initially used as the most active HER catalysts for Si-based photocathodes, while recently, their nanostructures have drawn more attention to the plasmonic effect of electron transfer at the interface of Si/cocatalysts. Localized surface plasmon resonance (LSPR) can be triggered by accurately regulating the size and geometry of noble metal nanoparticles, which can enhance the light-harvesting capability in the surface-near region and excite vast electrons under light illumination. , …”

“…Localized surface plasmon resonance (LSPR) can be triggered by accurately regulating the size and geometry of noble metal nanoparticles, which can enhance the lightharvesting capability in the surface-near region and excite vast electrons under light illumination. 38,39 Interface Charge Transfer. The narrow band gap of Si results in a limited photovoltage generated through the Si/ electrolyte junction.…”

“…57 Ge and coworkers embedded Au nanorings (NRs) into Si nanohole arrays with TiO 2 layers, finding that controlling the geometry and size of the Au NRs could trigger the LSPR effect. 38 By simulating the electric field distribution at 560 nm, as shown in Figure 3a,b, the hot electrons are concentrated on the top of the Au NRs adjacent to the Schottky junction, which is favorable for electron transfer through the junction. Similarly, Liu and colleagues utilized plasmonic Ag on Si microwire arrays and systematically investigated the LSPR effect of Ag nanostructures for PEC HER.…”