The influence of synthesis conditions on the visible-light triggered photocatalytic activity of g-C3N4/TiO2 composites used in AOPs

Roškarič, Matevž; Žerjav, Gregor; Zavašnik, Janez; Pintar, Albin

doi:10.1016/j.jece.2022.107656

Cited by 21 publications

(12 citation statements)

References 43 publications

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“…The magnitude of the upward shift is higher for the m-gC 3 N 4 /TiO 2 -nt (red filled square) composites as a result of high interaction areas between the two materials. Although the upward shift is low for the composite b-gC 3 N 4 /TiO 2 -nt (black filled circle), the type of interaction is promotional (upward shift), suggesting that the formation of the composite between TiO 2 and g-C 3 N 4 is beneficial in enhanced photocatalytic activity as evidenced by the literature. − The H 2 evolution rate of m-gC 3 N 4 /TiO 2 -nt ( x = 0.6) shows the highest value (∼65 μmol/h), which is about 3 times higher than that of the b-gC 3 N 4 /TiO 2 -nt ( x = 0.6) and about 6 times higher than that of pure TiO 2 -nt ( x = 0). The origin of the promotional effect of the interaction should be the separation of photoexcited charge carriers at the contact between g-C 3 N 4 and TiO 2 .…”

Section: Resultsmentioning

confidence: 81%

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C₃N₄/TiO₂ Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Wang

Fiaz

Kim

et al. 2023

ACS Appl. Energy Mater.

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Composite materials based on g-C3N4 and TiO2 nanotubes have been synthesized as environmentally friendly photocatalysts with heterojunctions suitable for enhanced photocatalytic hydrogen production. Composites were prepared with various ratios (x = 0–1) of g-C3N4 and after chemical modification and exfoliation of bulk g-C3N4. Contact formation between g-C3N4 and TiO2 generally enhanced photoactivity, which caused the x-dependent changes in the photocatalytic hydrogen evolution rates of the g-C3N4/TiO2 compounds to vary following a volcano-shaped curve with the maximum rate at x ∼ 0.6 for all the compounds regardless of the pretreatment (bulk or modified) of g-C3N4. The modified g-C3N4-based composites showed higher photoactivities than the unmodified bulk g-C3N4 due to the high surface area. The major reason for the enhanced photoactivity with the volcano shape was attributed to the Z-scheme interaction at the heterojunction. Interestingly, detailed analysis of the kinetic H2 evolution rates of the composites with Pt cocatalysts only on TiO2 nanotubes further showed that the dominant type of interaction at the heterojunctions changed from the type-II heterojunction to the Z-scheme at x ∼ 0.1. It is inferred that structural diversity at the g-C3N4/TiO2 interfaces is the origin of the changes in the dominant type of interaction in the composites with increasing ratios of g-C3N4.

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Section: Resultsmentioning

confidence: 81%

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C₃N₄/TiO₂ Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Wang

Fiaz

Kim

et al. 2023

ACS Appl. Energy Mater.

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“…On the other hand, the applicability of g-C 3 N 4 as a photocatalyst is limited owing to its low specific surface area and fast charge carrier recombination [1]. Roškarič et al [93] showed that simple mortar milling of previously prepared g-C 3 N 4 and TiO 2 can form a junction between the phases that enables the injection of visible-light-generated electrons from the conduction band of g-C 3 N 4 to the conduction band of TiO 2 , thus prolonging the lifetime of charge carriers. The charge carrier recombination rate of TiO 2 + g-C 3 N 4 was further reduced by annealing of the TiO 2 + g-C 3 N 4 composite at 350 °C, which owing to the relative thermal (in)stability of g-C 3 N 4 , increased the interface area between the components and thus enabled better injection of the visible-light-generated g-C 3 N 4 electrons.…”

Section: Semiconductor Couplingmentioning

confidence: 99%

Solar-Driven Photocatalytic Films: Synthesis Approaches, Factors Affecting Environmental Activity, and Characterization Features

et al. 2022

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Solar-powered photocatalysis has come a long way since its humble beginnings in the 1990s, producing more than a thousand research papers per year over the past decade. In this review, immobilized photocatalysts operating under sunlight are highlighted. First, a literature review of solar-driven films is presented, along with some fundamental operational differences in relation to reactions involving suspended nanoparticles. Common strategies for achieving sunlight activity from films are then described, including doping, surface grafting, semiconductor coupling, and defect engineering. Synthetic routes to fabricate photocatalytically active films are briefly reviewed, followed by the important factors that determine solar photocatalysis efficiency, such as film thickness and structure. Finally, some important and specific characterization methods for films are described. This review shows that there are two main challenges in the study of photocatalytic materials in the form of (thin) films. First, the production of stable and efficient solar-driven films is still a challenge that requires an integrated approach from synthesis to characterization. The second is the difficulty in properly characterizing films. In any case, the research community needs to address these, as solar-driven photocatalytic films represent a viable option for sustainable air and water purification.

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“…Therefore, the main objective of the research work presented here was to optimize the parameters of the onestep g-C 3 N 4 synthesis procedure 5 using dicyandiamide to obtain g-C 3 N 4 with a higher specific surface area for enhanced photocatalytic reaction under visible-light and simulated sunlight illumination. To achieve this goal, we used the modified Simplex method to find the global maximum in only a few steps.…”

Section: Introductionmentioning

confidence: 99%

Optimization Method Based on Simplex for Surface Area Improved Photocatalytic Performance of g-C₃N₄

Roškarič,

Zavašnik,

Zámbó

et al. 2023

ACS Catal.

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The main objective of the present study was to increase the specific surface area (S BET) of graphitic carbon nitride (g-C3N4) prepared from dicyandiamide by effectively modifying the synthesis procedure using the Simplex optimization method. A remarkable increase in S BET was achieved in only a few steps, with the highest value of 86 m2/g. Compared to the reference material, the improved photocatalyst exhibited enhanced and unique structural, textural, optical, and electronic properties, reflected in the improved ability of the photocatalyst to degrade a variety of organic pollutants dissolved in water. By performing scavenger and spin-trapping experiments, it was confirmed that the major reactive oxygen species formed under visible-light illumination of the enhanced photocatalyst were singlet oxygen (1O2) and superoxide anion radicals (O2 –•) with a purposed formation mechanism. The enhanced formation of 1O2 enabled high activity and stability of the optimized materials as well as selective response to degradation of the pharmaceutical compounds studied. By using the simple and fast Simplex optimization algorithm to determine new synthesis parameters, we obtained an improved g-C3N4 that completely degrades bisphenol A under the conditions studied.

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The influence of synthesis conditions on the visible-light triggered photocatalytic activity of g-C3N4/TiO2 composites used in AOPs

Cited by 21 publications

References 43 publications

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C₃N₄/TiO₂ Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C₃N₄/TiO₂ Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Solar-Driven Photocatalytic Films: Synthesis Approaches, Factors Affecting Environmental Activity, and Characterization Features

Optimization Method Based on Simplex for Surface Area Improved Photocatalytic Performance of g-C₃N₄

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The influence of synthesis conditions on the visible-light triggered photocatalytic activity of g-C3N4/TiO2 composites used in AOPs

Cited by 21 publications

References 43 publications

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C3N4/TiO2 Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C3N4/TiO2 Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Solar-Driven Photocatalytic Films: Synthesis Approaches, Factors Affecting Environmental Activity, and Characterization Features

Optimization Method Based on Simplex for Surface Area Improved Photocatalytic Performance of g-C3N4

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Product

Resources

About

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C₃N₄/TiO₂ Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Kinetic Evidence for Type-II Heterojunction and Z-Scheme Interactions in g-C₃N₄/TiO₂ Nanotube-Based Photocatalysts in Photocatalytic Hydrogen Evolution

Optimization Method Based on Simplex for Surface Area Improved Photocatalytic Performance of g-C₃N₄