K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment

HIGHLIGHTS

In this work, for the first time, we used K3Fe(CN)6 chemical as a suitable precursor for the simultaneous growth of Fe3N and Fe2O3 nanocrystals through polymerization of melamine leading to the formation of C3N4 as the major photocatalytic support. At the same time, K3Fe(CN)6 and Nb2O5 reacted efficiently to form the fourth electronic segment of the framework, K4Nb6O17, which has been rarely reported earlier.

These four components reinforced each other under visible irradiation to reach an enhanced photocatalytic performance which was explored through acetamiprid pesticide photodegradation, CO2-to-methane photoreduction, and glioblastoma cancer cells eradication. Generally, photocatalytic treatment of the cancer cells has not been widely studied and U87-MG cancer cells photoinactivation over the current photocatalyst was reported for the first time.

Quenching experiments besides the results of spin-trapping ESR were utilized to recognize the main radical species promoting the photoreactions. Accordingly, the •OH radicals were determined to have the major role. In this work, the mechanism of charge carriers’ transfer was comprehensively discussed based on the electronic structure of the components and their performances. According to the evidences, the S-scheme pathway was suggested to be the main pathway to result in the efficient formation of OH radicals over the aforementioned photocatalyst.

Significance 

Photocatalytic remediation of environmental pollution, such as degradation of care products, pesticides, herbicides, and killing of cancer cells, has become the main focus in chemical and science technology. This is why organic and inorganic-based photocatalysts such as g-C3N4 and TiO2-based composites have become promising candidates for the remediation of various pollutants.

In addition, photocatalytic reduction of carbon dioxide to produce methane (renewable energy) using heterogeneous photocatalysts has also received tremendous research attention in the removal of atmospheric CO2. Among the new materials with the potential to improve the efficiency of the above processes, heterojunction photocatalysts are more favorable than pure materials owing to two advantages of heterojunction structures. They include unique electronic properties and better light absorption.

Photocatalysts are also promising in reducing unwanted side effects of cancer treatment processes. In particular, the role of reactive oxygen species of these compounds in killing cancer cell lines has been investigated. Despite the numerous applications of photocatalytic semiconductors, several drawbacks such as difficulties in recycling from the treated media, high electron-hole recombination rate, and significant bandgap values still restrict practical photocatalytic applications of the pure semiconductors. Therefore, researchers have devoted their efforts to designing and preparing new efficient composite materials. Among them, ternary and quaternary photocatalysts are promising candidates for CO2 reduction and environmental remediation.

Various forms of semiconductors such as perovskites, metal oxides, silver halides, and more, have been applied to develop efficient photosensitive frameworks. 2D layered transition metal oxides are also ideal candidates going by their unique electronic structures. Heterojunction composite preparation of K4Nb6O17 nanosheets with g-C3N4 would be necessary to improve the photocatalytic features of g-C3N4 in the composite framework. However, considering that most photocatalysts are used in powder form, there are emerging concerns of their separation and recycling after treatment, leading to photocatalysts loss and photocatalysts particles becoming secondary pollutants.

In light of these drawbacks, smart and recyclable materials are emerging as immediate remedies based on their magnetic characteristics. Iron nitride is one such material that is attractive as an active material in battery applications. Even so, the synergistic effect of its unique magnetic and electronic features on photocatalytic activity hasn’t been investigated extensively yet. Therefore, it is particularly necessary to investigate magnetic-C3N4-based photocatalyst using Fe3N to develop an efficient photocatalyst for energy production and wastewaters remediation.

Researchers Dr. Mohsen Padervand from University of Maragheh, Shahnaz Ghasemi from Sharif University of Technology, Sima Hajiahmadi from Shahid Beheshti University of Medical Sciences, together with distinguished professor Chuanyi Wang from the Shaanxi University of Science & Technology, prepared a reusable quaternary K4Nb6O17/α-Fe2O3/Fe3N/g-C3N4 photocatalyst through a one-step thermal pyrolysis process and applied it for CO2 reduction and photodegradation of acetamiprid pesticide. They also evaluated its photocatalytic activity towards U87-MG cell eradication. The original research article is now published in the journal Applied Surace Science.

The research team prepared the new magnetic K4Nb6O17/α-Fe2O3/Fe3N/g-C3N4 photocatalyst via a simple one-step thermal pyrolysis method. They characterized the photocatalyst and evaluated its photocatalytic activity towards CO2 reduction and photodegradation of acetamiprid pesticide. The authors also investigated its anti-proliferative effects on human glioblastoma cancer cells which is one of the deadliest types of cancers.

Through various elegant characterization techniques, the researchers were able to confirm the successful formation of quaternary crystalline structure. According to Vibrating Sample Magnetometer and DRS, the authors recorded the magnetic saturation and optical bandgap as 12 emu/g and 2.75 eV, respectively. These values implied that the reusable quaternary photocatalyst could harvest visible photons quickly.

The authors confirmed the recyclability of the prepared reusable photocatalyst by the recorded 76% removal of acetamiprid after five consecutive runs. They investigated charge carriers’ transfer in the junctions through spin-trapping electron paramagnetic resonance analysis and quenching experiments. The results indicated that OH radicals were the most efficient photoactive agents that promoted acetamiprid photodegradation.

The researchers successfully recorded evolution rates of 7.01 and 1.3 μmol g−1 h−1 over K4Nb6O17/α-Fe2O3/Fe3N/g-C3N4 under irradiation for CO and methane, respectively. The figures were almost 14.6 times higher than those of over g-C3N4. Also, the researchers confirmed that the new magnetic photocatalyst had appreciable efficacy in eradicating U87-MG cells under visible light. In all, the findings of this study suggest that this novel quaternary photocatalyst has vast potential in medical therapy as well as other applications in energy production and wastewater remediation processes. In a statement to Advances in Engineering, Dr. Mohsen Padervand, first author said: from my point of view, this work provides not only alternative route for the preparation of Fe3N and Fe2O3 included photocatalysts but also a convenient and highly efficient method for improving the photocatalytic performance of other materials i.e. commercial TiO2, ZnO, etc.

K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment - Advances in Engineering K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment - Advances in Engineering K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment - Advances in Engineering K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment - Advances in Engineering K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment - Advances in Engineering

About the author

Dr. Chuanyi Wang, Fellow of Royal Society of Chemistry (FRSC), academic dean and distinguished professor at School of Environmental Science & Engineering, Shaanxi University of Science & Technology (SUST), China. Before moving to SUST in the summer of 2017, he was a distinguished professor of Chinese Academy of Sciences (CAS), serving as Director of Laboratory of Environmental Science & Technology of Xinjiang Technical Institute of Physics & Chemistry, CAS, and Head of CAS-SAFEA International Partnership Program for Creative Research Teams (2010-2017). Dr. Wang obtained his Ph.D. degree with honor from Institute of Photographic Chemistry of CAS in 1998, worked in Germany (Institute for Solar Energy Research in Hannover and Free University Berlin) as an Alexander von Humboldt (AvH) research fellow with Prof. Detlef Bahnemann from 1999 to 2000, and then worked in USA (Tufts University and Missouri University-Kansas City) as a postdoc and research faculty from 2000 to 2010.

Currently, Dr. Wang also serves as an associate editor of Environmental Chemistry Letters, and works as an editorial board member for number of international journals. Dr. Wang’s research interest covers catalysis and photo-/electrocatalysis at nanostructured materials, including material design, synthesis, functionality evaluation and in situ surface probe studies with focus on applications in photo-/electrochemical energy conversion and environmental remediation. By far, he has published over 250 papers in peer reviewed journals with an H-index of 59.

About the author

Mohsen Padervand is an associate professor at University of Maragheh, Maragheh, Iran. He received his doctoral degree in physical chemistry from Sharif University of Technology, Tehran, Iran, in 2013. He started his career at University of Maragheh in 2015. He has been working at the Department of Chemistry, University of Maragheh since September 2015.

His research interests include photocatalysis and waste treatment, preparation and characterization of materials, development of novel semiconducting nanomaterials, and the mechanism of contaminants removal under light. Webpage link:

Reference

Mohsen Padervand, Shahnaz Ghasemi, Sima Hajiahmadi, and Chuanyi Wang. K4Nb6O17/Fe3N/α-Fe2O3/C3N4 as an enhanced visible-light-driven quaternary photocatalyst for acetamiprid photodegradation, CO2 reduction, and cancer cells treatment. Applied Surface Science, issue 544 (2021), 148939

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