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Improving photocatalytic hydrogen generation of g-C3N4 via efficient charge separation imposed by Bi2O2Se nanosheets.

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Title: Improving photocatalytic hydrogen generation of g-C3N4 via efficient charge separation imposed by Bi2O2Se nanosheets.
Authors: Lin, Ci1 (AUTHOR), Zhao, Xiaolong1 (AUTHOR) zhaoxl@hku.hk, Xiao, Yejun2 (AUTHOR), Sattar, Shahid3 (AUTHOR), Tang, Lei4 (AUTHOR), Nairan, Adeela5 (AUTHOR), Guo, Yu1 (AUTHOR), Xia, Mingyu1 (AUTHOR), Canali, Carlo Maria3 (AUTHOR), Khan, Usman1,5 (AUTHOR) usman@zstu.edu.cn, Leung, Dennis Y.C.1 (AUTHOR) ycleung@hku.hk
Source: Carbon. Jan2024, Vol. 218, pN.PAG-N.PAG. 1p.
Subjects: Interstitial hydrogen generation, Nitrides, Nanostructured materials, Quantum efficiency, Photocatalysts, Electron configuration, Hydrogen production, Hydrogen evolution reactions
Abstract: Enabling highly efficient photocatalytic hydrogen production from solar-driven water splitting is of immense potential and environmental significance. However, the crucial issue of the low utilization efficiency of photogenerated charges in most photocatalysts, such as polymeric graphitic carbon nitride, g-C 3 N 4 (CN), hampers the overall photocatalytic activity and hinders practical applications. To surmount this parasitic phenomenon, we develop a heterojunction-based strategy that improves the charge separation efficiency in CN. The heterostructure is constructed between thermally exfoliated CN and liquid phase exfoliated Bi 2 O 2 Se (BOS) via a solution-phase, electrostatically driven self-assembly process. The properly aligned band positions between the two components create a built-in electric field, which endows the composite with an enhanced charge separation efficiency. The optimized Pt-deposited heterostructure photocatalyst exhibits a hydrogen production rate of 6481 μmol h−1 g−1, and an apparent quantum efficiency of 11.65% at 420 nm, compared to those of Pt-deposited ECN (4595 μmol h−1 g−1, 6.64 %). We validate the efficient charge separation effect and the prolonged lifetime of photogenerated carriers in the heterostructure using a series of comprehensive characterizations across multiple timescales, thus, elucidating the origin of the observed photocatalytic activity. This demonstration offers valuable insights into improving the utilization efficiency of photogenerated charges for photocatalysis by heterostructure engineering with materials of distinct electronic configurations. [Display omitted] • A heterostructure composed of thermally exfoliated g-C 3 N 4 and liquid phase exfoliated Bi 2 O 2 Se was facilely obtained via a solution phase self-assembly. • The addition of Bi 2 O 2 Se to g- C 3 N 4 increases the separation efficiency of photogenerated charges. • The 2.5BOS/ECN/Pt composite photocatalyst exhibits a boosted hydrogen generation rate of 6481 μmol h−1 g−1 and an improved apparent quantum efficiency of 11.65% at 420 nm. • Photodynamic measurement indicates effective retardation of the intrinsic recombination of photogenerated charges. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Enabling highly efficient photocatalytic hydrogen production from solar-driven water splitting is of immense potential and environmental significance. However, the crucial issue of the low utilization efficiency of photogenerated charges in most photocatalysts, such as polymeric graphitic carbon nitride, g-C 3 N 4 (CN), hampers the overall photocatalytic activity and hinders practical applications. To surmount this parasitic phenomenon, we develop a heterojunction-based strategy that improves the charge separation efficiency in CN. The heterostructure is constructed between thermally exfoliated CN and liquid phase exfoliated Bi 2 O 2 Se (BOS) via a solution-phase, electrostatically driven self-assembly process. The properly aligned band positions between the two components create a built-in electric field, which endows the composite with an enhanced charge separation efficiency. The optimized Pt-deposited heterostructure photocatalyst exhibits a hydrogen production rate of 6481 μmol h−1 g−1, and an apparent quantum efficiency of 11.65% at 420 nm, compared to those of Pt-deposited ECN (4595 μmol h−1 g−1, 6.64 %). We validate the efficient charge separation effect and the prolonged lifetime of photogenerated carriers in the heterostructure using a series of comprehensive characterizations across multiple timescales, thus, elucidating the origin of the observed photocatalytic activity. This demonstration offers valuable insights into improving the utilization efficiency of photogenerated charges for photocatalysis by heterostructure engineering with materials of distinct electronic configurations. [Display omitted] • A heterostructure composed of thermally exfoliated g-C 3 N 4 and liquid phase exfoliated Bi 2 O 2 Se was facilely obtained via a solution phase self-assembly. • The addition of Bi 2 O 2 Se to g- C 3 N 4 increases the separation efficiency of photogenerated charges. • The 2.5BOS/ECN/Pt composite photocatalyst exhibits a boosted hydrogen generation rate of 6481 μmol h−1 g−1 and an improved apparent quantum efficiency of 11.65% at 420 nm. • Photodynamic measurement indicates effective retardation of the intrinsic recombination of photogenerated charges. [ABSTRACT FROM AUTHOR]
ISSN:00086223
DOI:10.1016/j.carbon.2023.118721