Microwave hydrothermal synthesis of copper induced ZnO/gC3N4 heterostructure with efficient photocatalytic degradation through S-scheme mechanism

Swamy, Chandrakantha Kampalapura; Hezam, Abdo; Ramesh, Abhilash Mavinakere; Ramakrishnegowda, Deepu Habbanakuppe; Purushothama, Dhananjay K.; Jagadish, K.; Kanchugarakoppal, S Rangappa; Srikantaswamy, S.

doi:10.1016/j.jphotochem.2021.113394

Cited by 23 publications

(2 citation statements)

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“…The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/nano14010103/s1, Figure S1 S1: Normalized reaction rate (k) values for the MO photodegradation reaction in the presence of photocatalytic samples exfoliated at 550 • C and 600 • C; Table S2: Performance of C 3 N 4 -based samples for degradation of MO under visible light irradiation in recently published literature. References [131][132][133][134][135][136][137][138][139][140][141] are cited in the Supplementary Materials.…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…The following supporting information can be downloaded at: , Figure S1: TEM images of thermally exfoliated g-C 3 N 4 samples: (a and b) 550-CN and (c and d) 600-CN; Figure S2: g-C 3 N 4 sample ultrasonicated in acid media for 40 min; Figure S3: Enlarged view of (002) peak of XRD for g-C 3 N 4 samples; Figure S4: DRS spectra of g-C 3 N 4 samples prepared under different conditions; Figure S5: Pore size distribution curves of different g-C 3 N 4 samples; Figure S6: Visible light degradation spectra of MO using samples (a) 500-CN, (b) 500-UCN, (c) 550-CN, (d) 550-UCN, (e) 550-AUCN, (f) 600-CN, (g) 600-UCN, and (h) 600-AUCN; Figure S7: Photocatalytic degradation of MO under visible light using photocatalyst samples exfoliated at 550 °C; Figure S8: Photocatalytic degradation of MO under visible light, using photocatalyst samples exfoliated at 600 °C; Figure S9: Photocatalytic stability of 500-AUCN in four successive cycling reactions under visible light irradiation; Table S1: Normalized reaction rate ( k ) values for the MO photodegradation reaction in the presence of photocatalytic samples exfoliated at 550 °C and 600 °C; Table S2: Performance of C 3 N 4 -based samples for degradation of MO under visible light irradiation in recently published literature. References [ 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 ] are cited in the Supplementary Materials.…”

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Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

Kalantari Bolaghi,

Rodriguez-Seco,

Yurtsever

et al. 2024

Nanomaterials

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Graphitic carbon nitride (g-C3N4) is a metal-free photocatalyst used for visible-driven hydrogen production, CO2 reduction, and organic pollutant degradation. In addition to the most attractive feature of visible photoactivity, its other benefits include thermal and photochemical stability, cost-effectiveness, and simple and easy-scale-up synthesis. However, its performance is still limited due to its low absorption at longer wavelengths in the visible range, and high charge recombination. In addition, the exfoliated nanosheets easily aggregate, causing the reduction in specific surface area, and thus its photoactivity. Herein, we propose the use of ultra-thin porous g-C3N4 nanosheets to overcome these limitations and improve its photocatalytic performance. Through the optimization of a novel multi-step synthetic protocol, based on an initial thermal treatment, the use of nitric acid (HNO3), and an ultrasonication step, we were able to obtain very thin and well-tuned material that yielded exceptional photodegradation performance of methyl orange (MO) under visible light irradiation, without the need for any co-catalyst. About 96% of MO was degraded in as short as 30 min, achieving a normalized apparent reaction rate constant (k) of 1.1 × 10−2 min−1mg−1. This represents the highest k value ever reported using C3N4-based photocatalysts for MO degradation, based on our thorough literature search. Ultrasonication in acid not only prevents agglomeration of g-C3N4 nanosheets but also tunes pore size distribution and plays a key role in this achievement. We also studied their performance in a photocatalytic hydrogen evolution reaction (HER), achieving a production of 1842 µmol h−1 g−1. Through a profound analysis of all the samples’ structure, morphology, and optical properties, we provide physical insight into the improved performance of our optimized porous g-C3N4 sample for both photocatalytic reactions. This research may serve as a guide for improving the photocatalytic activity of porous two-dimensional (2D) semiconductors under visible light irradiation.

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Section: Supplementary Materialsmentioning

confidence: 99%

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confidence: 99%

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

Kalantari Bolaghi,

Rodriguez-Seco,

Yurtsever

et al. 2024

Nanomaterials

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Emerging S‐Scheme Photocatalyst

et al. 2022

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strategies in addressing the low-efficiency issue will be discussed.Photocatalysis mainly deals with electron and energy transfer processes. Prior to the discussion, it is necessary to learn the basic behaviors of the excited state of a molecule, which can enhance the understanding on electron transfer and energy dissipation in semiconductors. Generally, the first process is the absorption of a photon by a molecule (in the time scale of femtoseconds (fs)), where the ground state is lifted energetically to the first excited singlet state. Subsequently, a simplified Jablonski diagram is reconsidered, [2] as shown in Figure 1. The charge carriers generated in one molecule experience several possible processes with varying possibilities: [3] a) Vibrational relaxation (VR): it is relaxation of excited state electrons to the lowest energy level which generally occurs in picoseconds (ps). It can happen from each excited state to each non-excited state including the ground state. This VR results in loss of energy because excessive vibrational energy is converted into heat. b) Fluorescence: After the relaxation to the lowest vibrational level, the excited molecule can finally get back to the ground state by emitting a photon. This is named as fluorescence, which occurs in a relatively long time, ranging from ps to nanoseconds (ns). c) Internal conversion (IC): it is a crossover process in which an electronically excited molecule moves from one electronic state to a lower one of the same multiplicity (singlet-to-singlet or triplet-to-triplet states) and can be measured from ps to fs. [4] d) Intersystem crossing (ISC): A transition from one electronic state to another one with a different spin multiplicity is called ISC. e) Phosphorescence: After the molecule transitions through ISC to the triplet state, further deactivation occurs through phosphorescence. And its lifetime ranges from one millisecond (ms) to hundreds of seconds. Apart from these, other processes such as vibrational cooling are also possible, which are not illustrated here.The above-mentioned processes in a single molecule can be used as a reference when discussing a semiconductor photocatalyst. Analogously, electrons are excited to the conduction band (CB) after absorption. Afterward, they will undergo several decay processes or they will finally migrate to the surface and participate in a specific redox reaction. These decay processes are briefly introduced here by comparing with those in a molecule (Figure 1): a) Relaxation of electrons to the lowest CB energy states. b) Radiative recombination of electrons and holes via emitted as fluorescence; c) Non-radiative decay, also referred to as Photocatalysis is a green technology to use ubiquitous and intermittent sunlight. The emerging S-scheme heterojunction has demonstrated its superiority in photocatalysis. This article covers the state-of-the-art progress and provides new insights into its general designing criteria. It starts with the challenges confronted by single photocatalyst from the perspective of...

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Construction of Bi₂S₃/TiO₂/MoS₂ S‐Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO₂ Reduction

et al. 2021

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Switching between the redox potential of an appropriate semiconductor heterostructure could show critical applications in selective CO2 reduction. Designing a semiconductor photocatalyst with a wavelength‐dependent response is an effective strategy for regulating the direction of electron flow and tuning the redox potential. Herein, the switching mechanism between two charge migration pathways and redox potentials in a Bi2S3/TiO2/MoS2 heterostructure by regulating the light wavelength is achieved. In situ irradiated X‐ray photoelectron spectroscopy (ISI‐XPS), electron spin resonance (ESR), photoluminescence (PL), and experimental scavenger analyses prove that the charge transport follows the S‐scheme approach under UV–vis–NIR irradiation and the heterojunction approach under vis–NIR irradiation, confirming the switchable feature of the Bi2S3/TiO2/MoS2 heterostructure. This switchable feature leads to the reduction of CO2 molecules to CH3OH and C2H5OH under UV–vis–NIR irradiation, while CH4 and CO are produced under Vis–NIR irradiation. Interestingly, the apparent quantum efficiency of the optimal composite at λ = 600 nm is 4.23%. This research work presents an opportunity to develop photocatalysts with switchable charge transport and selective CO2 reduction.

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Microwave hydrothermal synthesis of copper induced ZnO/gC3N4 heterostructure with efficient photocatalytic degradation through S-scheme mechanism

Cited by 23 publications

References 43 publications

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

Emerging S‐Scheme Photocatalyst

Construction of Bi₂S₃/TiO₂/MoS₂ S‐Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO₂ Reduction

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Microwave hydrothermal synthesis of copper induced ZnO/gC3N4 heterostructure with efficient photocatalytic degradation through S-scheme mechanism

Cited by 23 publications

References 43 publications

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets

Emerging S‐Scheme Photocatalyst

Construction of Bi2S3/TiO2/MoS2 S‐Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO2 Reduction

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Construction of Bi₂S₃/TiO₂/MoS₂ S‐Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO₂ Reduction