How g-C3N4Works and Is Different from TiO2as an Environmental Photocatalyst: Mechanistic View

Jonghun Lim, Hyejin Kim, Jihee Park, Gun Hee Moon, Junie Jhon M. Vequizo, Akira Yamakata, Jinwoo Lee, Wonyong Choi

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

Graphitic carbon nitride (CN) as a popular visible light photocatalyst needs to be better understood for environmental applications. The behaviors of CN as an environmental photocatalyst were systematically studied in comparison with a well-known TiO2photocatalyst. The two photocatalysts exhibit different photocatalytic oxidation (PCO) behaviors and dependences on the experimental conditions (e.g., pH, Pt loading, and the kind of organic substrate and scavenger). The PCO of organic substrates was significantly enhanced by loading Pt on TiO2under UV light (λ > 320 nm), whereas Pt-CN exhibited a lower PCO activity than bare CN under visible light (λ > 420 nm). While the presence of Pt enhances the charge separation in both TiO2/UV and CN/visible light systems (confirmed by transient IR absorption spectroscopic analysis), the opposite effects of Pt are ascribed to the different mechanisms of OH generation in the two photocatalytic systems. The negative effect of Pt on CN is ascribed to the fact that Pt catalytically decomposes in situ-generated H2O2(a main precursor of OH radical), which hinders OH production. The production of OH radicals on CN is favored only at acidic pH but 1O2generation is dominant in alkaline pH. The pH-dependent behaviors of reactive oxygen species generation on CN were confirmed by electron paramagnetic resonance spin trap measurements.

Original languageEnglish
Pages (from-to)497-506
Number of pages10
JournalEnvironmental Science and Technology
Volume54
Issue number1
DOIs
Publication statusPublished - Jan 7 2020
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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