Insights into the Most Suitable TiO₂ Surfaces for Photocatalytic O₂ and H₂ Evolution Reactions from DFT Calculations

Abstract

TiO 2 is considered as one of the most common photocatalysts for UV light-driven photocatalysis. We present here the effect of exposed facets on the photocatalytic features of anatase and rutile TiO 2 crystals using first-principle computations based on the density functional theory (DFT). The four possible low-Miller-index ( 110), ( 101), (100), and (001) surfaces of each crystalline phase are investigated. The most suitable facets for hydrogen and oxygen evolution reactions (HER and OER, respectively) are identified on anatase and rutile TiO 2 from the combination of the anisotropic redox and charge carrier transport properties. Our study demonstrates the (110) anatase surface as the most suitable candidate for OER, followed by the (101) surface, whereas the (001) anatase surface is predicted as the most suitable candidate for HER. For rutile, the two ( 110) and ( 101) surfaces are predicted as the most suitable candidates for OER, while no suitable surface candidate is found for HER in line with the experimental observations showing better activity for HER using anatase than rutile. These findings will guide experimentalists to carefully design (110)-and (001)-oriented anatase TiO 2 material samples for improved photocatalytic water oxidation and proton reduction.

Designing an active Ta3N5 photocatalyst for H2 and O2 evolution reactions by specific exposed facet engineering: a first-principles study

“…[24][25][26][27][28][29][30] Using this scheme, we recently identified the most appropriate exposed facets of TiO 2 (in anatase and rutile phases) for photocatalytic hydrogen and oxygen evolution reactions by combining their optoelectronic and redox properties. 33 Our predicted results could successfully give rational insights into the fundamental origin behind the better activity of anatase for HER compared to rutile as found in experiments. [33][34][35][36] In this paper, we introduce a systematic study on the impact of intrinsic defects and exposed facets on the optoelectronic and redox features of a Ta 3 N 5 water splitting photocatalyst by applying the DFT/HSE06 method.…”

“…33 Our predicted results could successfully give rational insights into the fundamental origin behind the better activity of anatase for HER compared to rutile as found in experiments. [33][34][35][36] In this paper, we introduce a systematic study on the impact of intrinsic defects and exposed facets on the optoelectronic and redox features of a Ta 3 N 5 water splitting photocatalyst by applying the DFT/HSE06 method. We explored three potential candidates of O-enriched bulk Ta 3 N 5 structures.…”

Significant Impact of Exposed Facets on the BiVO4 Material Performance for Photocatalytic Water Splitting Reactions

“… 5 − 9 , 32 − 36 , 39 , 40 Recently, ideal exposed facets for OER and HER of the widely utilized UV light- and visible light-driven photocatalysts, TiO 2 and Ta 3 N 5 , were predicted on the basis of an optoelectronic and redox characteristics combination using this computational scheme and relevant information was proposed for improving materials performance. 41 , 42 …”

Theoretical calculation of a TiO2-based photocatalyst in the field of water splitting: A review

“…Although the electron-hole pair generated by photoexcitation of TiO 2 possesses a strong redox ability as a result of the wide band gap (E g = 3.0-3.2 eV), it does not effectively absorb visible light [4]. According to numerous experiments and theoretical calculations (Liu T. et al, December 2019, China United Test & Evaluation Qingdao CN110568122-A), the doping or heterojunction modification of TiO 2 not only effectively broadens its light absorption range but also substantially reduces the probability of photogenerated electron-hole pair recombination [5][6][7][8][9][10][11][12][13][14]. However, due to the complexity of the photocatalytic water-splitting reaction system, considerable controversy still exists regarding its reaction mechanism, reaction process, and kinetic behavior.…”

“…In addition to theoretical calculations of the structure of TiO 2 itself and the doped or heterojunction system [32][33][34][35][36][37][38], scholars have also conducted numerous theoretical calculations and experiments to determine the interaction between the TiO 2 surface and water molecules, the migration mechanism of photoproduced electron-hole pairs, recombination of electron-hole pairs and other steps in the process to obtain an understanding of the mechanism and essential laws of photocatalytic water splitting [39][40][41][42][43][44][45][46].…”