Flame Reduced TiO₂ Nanorod Arrays with Ag Nanoparticle Decoration for Efficient Solar Water Splitting

Abstract

Low photogenerated charge density and fast surface charge recombination of TiO2 are two critical factors hampering its solar-to-hydrogen conversion for photoelectrochemical water splitting. Herein, we demonstrate an efficient and facile flame reduction method to produce rich oxygen vacancies in single-crystal rutile TiO2 nanorod arrays without destroying the catalyst and conductive substrate at ambient conditions. The oxygen vacancies improve the conductivity of TiO2 and act as the role that intermediate electron donor increases the charge density. We further construct a Schottky junction by depositing Ag nanoparticles on the flame reduced TiO2 to enhance surface charge separation efficiency. The optimal TiO2 photoelectrodes exhibit an astonishing surface charge separation efficiency of 91% as well as photocurrent density as high as 1.52 mA cm–2 (at 1.23 V, vs reversible hydrogen electrode), which is ∼7.2 times that of the pristine rutile TiO2 (0.21 mA cm–2). This work demonstrates that the facile flame reduction method combined with Schottky junction construction exhibits significant application prospects for the enhanced solar conversion efficiency of metal oxide photoelectrodes.

Direct Evidence of an Efficient Plasmon-Induced Hot-Electron Transfer at an in Situ Grown Ag/TiO2 Interface for Highly Enhanced Solar H2 Generation

“…Two peaks (Figure (c) appear for O 1s at the binding energies of 528.8 and 530.4 eV, which correspond to O in TiO 2 and oxygen vacancies, respectively. All these peak positions are well matched with those of earlier reported Ag-TiO 2 systems. , Therefore, the XPS study of this sample gives further proof of the formation of Ag-TiO 2 film.…”

“…All these peak positions are well matched with those of earlier reported Ag-TiO 2 systems. 25,26 Therefore, the XPS study of this sample gives further proof of the formation of Ag-TiO 2 film.…”

Improving Photoelectrochemical Activity of ZnO/TiO2 Core–Shell Nanostructure through Ag Nanoparticle Integration

“…In the application of PEC water splitting, nanostructured semiconductor photoelectrode possesses a large surface-to-volume ratio (SVR), thus reducing the migration distance of photo-excited carriers and facilitating their transfer to surface. The heterojunctions integrating ZnO or TiO 2 with another semiconductor [26][27][28][29][30][31][32] or metal co-catalyst [33][34][35][36][37][38][39][40][41][42][43] have been explored by many researchers. Moreover, heterogeneous structures which combine more than two semiconductors or semiconductor-metal junctions have also been employed as an effective strategy to promote carrier separation, avoid the carrier recombination and improve solar energy conversion efficiency [44][45][46][47][48][49][50].…”

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

“…Lian et al [ 2 ] designed a plasmonic Ag/TiO 2 photocatalytic composite by selecting Ag quantum dots to act as the photosensitizer for driving the visible light-driven photoelectrocatalytic hydrogen evolution. Chen et al [ 3 ] deposited Ag nanoparticles on the flame reduced TiO 2 , which exhibits significant application prospects for the enhanced solar conversion efficiency. Mohammadi et al loaded Ag nanoparticles on TiO 2 nanotubes by sequential chemical bath deposition, and the photoelectrochemical (PEC) activity is considerably higher than the bare TiO 2 (about 3 times), owing to the light absorption improvement of plasmonic effects in addition to better separation and transport of electron–hole pairs [ 4 ].…”