Electrochemical Fabrication of rGO-embedded Ag-TiO2 Nanoring/Nanotube Arrays for Plasmonic Solar Water Splitting

Lixia Sang; Lei Lei; Clemens Burda

doi:10.1007/s40820-019-0329-2

Electrochemical Fabrication of rGO-embedded Ag-TiO₂ Nanoring/Nanotube Arrays for Plasmonic Solar Water Splitting

Nanomicro Lett. 2019 Nov 7;11(1):97. doi: 10.1007/s40820-019-0329-2.

Authors

Lixia Sang¹, Lei Lei², Clemens Burda³

Affiliations

¹ Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing, 100124, People's Republic of China. sanglixia@bjut.edu.cn.
² Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Municipality, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing, 100124, People's Republic of China.
³ Department of Chemistry, Center for Chemical Dynamics and Nanomaterials Research, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.

Abstract

Effective utilization of hot electrons generated from the decay of surface plasmon resonance in metal nanoparticles is conductive to improve solar water splitting efficiency. Herein, Ag nanoparticles and reduced graphene oxide (rGO) co-decorated hierarchical TiO₂ nanoring/nanotube arrays (TiO₂ R/T) were facilely fabricated by using two-step electrochemical anodization, electrodeposition, and photoreduction methods. Comparative studies were conducted to elucidate the effects of rGO and Ag on the morphology, photoresponse, charge transfer, and photoelectric properties of TiO₂. Firstly, scanning electron microscope images confirm that the Ag nanoparticles adhered on TiO₂ R/T and TiO₂ R/T-rGO have similar diameter of 20 nm except for TiO₂ R-rGO/T. Then, the UV-Vis DRS and scatter spectra reveal that the optical property of the Ag-TiO₂ R/T-rGO ternary composite is enhanced, ascribing to the visible light absorption of plasmonic Ag nanoparticles and the weakening effect of rGO on light scattering. Meanwhile, intensity-modulated photocurrent spectroscopy and photoluminescence spectra demonstrate that rGO can promote the hot electrons transfer from Ag nanoparticles to Ti substrate, reducing the photogenerated electron-hole recombination. Finally, Ag-TiO₂ R/T-rGO photoanode exhibits high photocurrent density (0.98 mA cm^-2) and photovoltage (0.90 V), and the stable H₂ evolution rate of 413 μL h^-1 cm^-2 within 1.5 h under AM 1.5 which exceeds by 1.30 times than that of pristine TiO₂ R/T. In line with the above results, this work provides a reliable route synergizing rGO with plasmonic metal nanoparticles for photocatalysis, in which, rGO presents a broad absorption spectrum and effective photogenerated electrons transfer.

Keywords: Plasmonic Ag nanoparticles; Reduced graphene oxide; Spectral responses; TiO2 nanoring/nanotube hierarchical structure; Water splitting.