CeO₂/TiO₂ Heterojunction Nanotube Arrays for Highly Efficient Visible-Light Photoelectrochemical Water Splitting

Abstract

Composite of rare earth oxides with TiO2 nanotube arrays can effectively modify the photoelectrochemical (PEC) behavior of TiO2. A CeO2/TiO2 heterojunction was prepared by loading CeO2 nanoparticles on anodized TiO2 nanotube (TNT) arrays for PEC water splitting. The CeO2/TNT electrode exhibited a high photocurrent density of 2.11 mA·cm–2, 4.3 times that of pure TNT (0.49 mA·cm–2) at 1.23 V vs RHE under AM 1.5G light. And CeO2/TNT realized a high PEC H2 evolution rate of 17.86 μmol/h, 4.5 times that of pure TNT at 1.55 V vs RHE. The effective performance of the CeO2/TNT electrode could be attributed to its reasonable band gap structure facilitating visible light absorption and efficient charge transfer, inhibiting the recombination of electron/hole pairs. This work confirms the successful construction of CeO2/TiO2 heterojunction on TNT arrays for improving the PEC performance of TiO2 for H2 production.

Silver-Boosted WO3/CuWO4 Heterojunction Thin Films for Enhanced Photoelectrochemical Water Splitting Efficiency

“…Producing clean and sustainable hydrogen fuel through photoelectrochemical (PEC) water splitting is an appealing approach and is regarded as a highly promising solution to the environmental crisis. , The remarkable aspect of hydrogen fuel is that it does not produce harmful greenhouse gases or air pollutants; instead, it only releases water as a byproduct, which makes it a promising alternative to conventional fossil fuels and a viable strategy to mitigate the adverse effects of climate change. For many years, researchers have extensively studied titanium dioxide (TiO 2 ) as a photoanode due to its remarkable photocatalytic activity, chemical and optical stability, and biocompatibility. , However, its wide band gap of approximately 3.2 eV restricts its capacity to utilize only ultraviolet (UV) light, representing a mere 4% of the solar spectrum. This limitation, coupled with the fast recombination of photogenerated electron–hole pairs, hinders its practical applications.…”

“…For many years, researchers have extensively studied titanium dioxide (TiO 2 ) as a photoanode due to its remarkable photocatalytic activity, chemical and optical stability, and biocompatibility. 3,4 However, its wide band gap of approximately 3.2 eV restricts its capacity to utilize only ultraviolet (UV) light, representing a mere 4% of the solar spectrum. This limitation, coupled with the fast recombination of photogenerated electron−hole pairs, hinders its practical applica- tions.…”

TiO2 spatially confined growth of Sb2(S,Se)3@TiO2 NT heterojunction photoanodes and their photoelectrochemical properties

“…36 Lin et al reported that the PEC performance of CeO 2 /TiO 2 heterojunctions constructed by chemically depositing CeO 2 nanoparticles loaded on TiO 2 NTs was 4.3 times higher compared to monomeric TiO 2 , which was attributed to the improved visible light absorption and optimized energy band. 37 Li et al confined growth of CdS nanoparticles within TiO 2 NTs by an ion-exchange method and sulfidation exhibiting enhanced photocatalytic activity and photostability, which can be attributed to the quantum size effect of CdS due to the space-confinement effect of TiO 2 NTs. 38 Antimony selenide sulfide Sb 2 (S,Se) 3 , a direct band gap semiconductor with an adjustable forbidden band width of 1.1-1.8 eV, had a high absorption coefficient (>10 5 cm −1 ) and can absorb photon energy in the near-infrared and visible regions.…”

Constructing Dual Cocatalysts of Ni2P–NiS-Decorated TiO2 for Boosting Photocatalytic H2 Evolution

“…18−20 However, the activity of a single TiO 2 is not ideal due to its wide band gap, poor absorption in visible light, and the high recombination rate of electrons and holes. 21−23 In order to accelerate the H 2 evolution process over TiO 2 , a number of strategies were adopted, such as morphology control, 24,25 element doping, 26,27 cocatalyst loading, 28−30 and heterojunction construction. 31−33 Among them, cocatalyst loading is an efficient method because it can efficiently increase the active sites, prevent charge recombination, and quicken oxidation−reduction reaction (REDOX) kinetics.…”

“…Since the first utilization of TiO 2 photoanode and Pt cathode for water splitting in 1972, the technology of H 2 production through water splitting has been received increasing attention from scientists in recent decades. , Afterward, TiO 2 photocatalysis has been widely investigated, including degradation of organic pollutants and reduction of CO 2 . − Due to its nontoxic and affordable characteristics, as well as its exceptional stability and photocorrosion resistance during H 2 evolution, TiO 2 as a traditional photocatalyst can still initiate research interest. − However, the activity of a single TiO 2 is not ideal due to its wide band gap, poor absorption in visible light, and the high recombination rate of electrons and holes. − In order to accelerate the H 2 evolution process over TiO 2 , a number of strategies were adopted, such as morphology control, , element doping, , cocatalyst loading, − and heterojunction construction. − Among them, cocatalyst loading is an efficient method because it can efficiently increase the active sites, prevent charge recombination, and quicken oxidation–reduction reaction (REDOX) kinetics . Noble metal nanoparticles, such as Au, Ag, and Pt, are the most efficient cocatalysts, but the high cost inhibits their extensive applications.…”